signals of climate variability/change in surface water...

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Signals of climate variability/change in surface water supply of high-mountain watersheds

Case study: Claro River high mountain basin, Los Nevados Natural Park, Andean Central Mountain Range

Chapter 6: Analysis of climatic conditions February 2009

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Signals of climate variability/change in surface water supply of high-mountain watersheds

Case study: Claro River high mountain basin, Los Nevados Natural Park, Andean Central Mountain Range

Contract 7147577 – The World Bank Group

Daniel Ruiz Carrascal Línea de Investigación en Hidroclimatología

Grupo de Investigación ‘Gestión del Ambiente para el Bienestar Social - GABiS’ Escuela de Ingeniería de Antioquia

Calle 25Sur No. 42-73, Envigado, Antioquia, Colombia Phone: (57-4) 339-3200; Fax: (57-4) 331 7851; E-mail: [email protected]

Chapter 6: Analysis of climatic conditions February 2009

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Escuela de Ingeniería de Antioquia

Executive, academia and research administration

President

Carlos Felipe Londoño Álvarez

Secretary

Olga Lucía Ocampo Toro

Dean of Engineering

Carlos Rodríguez Lalinde

Director of Research Activities

Nathalia Vélez López de Mesa

Director of Research Group ‘GABiS’

Maria del Pilar Arroyave Maya

Director of Environmental Engineering Program

Santiago Jaramillo Jaramillo

Research Team

Principal Investigator

Daniel Ruiz Carrascal

Co-PI

Maria del Pilar Arroyave Maya Adriana María Molina Giraldo Juan Fernando Barros Martínez

Research Assistants

Maria Elena Gutiérrez Lagoueyte Paula Andrea Zapata Jaramillo

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Table of content

6.1 Nationwide scale 9 6.2 Regional scale 14 6.3 Local scale 18 6.3.1 Available info 18 6.3.2 Climatology 28 6.3.3 Long-term trend 50

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Tables

# Page

6.1 Colombian hydrometeorological network 10 6.2 Available info from the Colombian hydrometeorological network 10 6.3 Met stations reporting monthly rainfall and located along the 5°N latitudinal transect 14 6.4 Met stations reporting monthly temperature and located along the 5°N latitudinal transect 14 6.5 Hydrometeorological network available in the spatial domain 04°25’-05°15’N and 75°00’-76°00’W 20 6.6 Regional stations included in the analysis of local conditions 20

6.7 Met stations operated by Instituto de Hidrología, Meteorología y Estudios Ambientales (IDEAM) and Central Hidroeléctrica de Caldas-CHEC

21

6.8 Met stations administered by Federación Nacional de Cafeteros de Colombia (Cenicafé) 23

6.9 Hydrometeorological network available in the spatial domain 04°40’-05°10’N and 75°10’-75°40’W and still collecting climatic data

26

6.10 LG and LM stations available in the spatial domain 04°25’-05°15’N and 75°00’-76°00’W 26

6.11 LG and LM stations available in the spatial domain 04°40’-05°10’N and 75°10’-75°40’W and still collecting data

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6.12 Percentage of the variance of SST anomalies explained by EOF modes 50 6.13 Correlation coefficients (R) between sea surface temperatures and all-type cloud amounts 52 6.14 Annual values of sunshine variables 52 6.15 Annual values of rainfall variables 54

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Figures

# Page

6.1 Colombian hydrometeorological network and available met stations 11 6.2 Colombian met stations located above 3,200 m 13 6.3 Trends in historical time series (exploratory analyses) – nationwide scale 13 6.4 Available met stations reporting monthly rainfall and located along the 5°N latitudinal transect 15 6.5 Available met stations reporting monthly temperature and located along the 5°N latitudinal transect 16 6.6 Regional rainfall conditions along the 5°N latitudinal transect 17 6.7 Regional temperature conditions along the 5°N latitudinal transect 18 6.8 Data of sea surface temperatures for the analysis of local conditions 19 6.9 Cloud characteristics for multiple clouds for the grid point 3556 19 6.10 Example of time series of total monthly rainfall for the analysis of local conditions 22 6.11 Observed trends (observatory analysis) in temperatures 25 6.12 Observed trends (observatory analysis) in sunshine, rainfall, evaporation, and relative humidity 25 6.13 Sample of met stations selected for the analysis of local conditions 27 6.14 Annual cycles of cloud characteristics for all type clouds and for the grid point 3556 28 6.15 Annual cycles of total sunshine and total foggy -null sunshine- days 30 6.16 Annual cycles of total sunshine and total sunny days 31 6.17 Annual cycles of daily maximum sunshine and daily minimum sunshine 32 6.18 Annual cycles of daily mean sunshine and standard deviation of daily sunshine 33 6.19 Annual cycles of sunshine observed at Station XVI 2613507 El Cedral 35 6.20 Annual cycles of total rainfall and total dry days 36 6.21 Annual cycles of total rainfall and maximum daily rainfall 37 6.22 Annual cycles of minimum temperatures observed on the warmest days 40 6.23 Annual cycles of minimum temperatures observed on the coldest days 41 6.24 Annual cycles of maximum temperatures observed on the warmest days 42 6.25 Annual cycles of maximum temperatures observed on the coldest days 43 6.26 Annual cycles of maximum and mean relative humidity values 45 6.27 Annual cycles of minimum and mean relative humidity values 46 6.28 Annual cycles of maximum and mean diurnal temperature range values 47 6.29 Annual cycles of minimum and mean diurnal temperature range values 48 6.30 Annual cycles of potential evaporation observed in the spatial domain 49 6.31 Annual cycles of dew point, vapor pressure, cloud cover, and wind speed 49 6.32 EOF modes of January SST anomalies observed in the Indo-Pacific region 50 6.33 Principal components of SST anomalies observed in the Indo-Pacific region 51

6.34 Estimated trends in the mean (confirmatory analysis) of total annual sunshine and total annual foggy days for the selected spatial domain

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6.35 Estimated trends in total annual rainfall and total number of dry days 55 6.36 Estimated trends in minimum temperatures observed during the coldest days 56 6.37 Estimated trends in maximum temperatures observed during the warmest days 57 6.38 Estimated trends in relative humidity 59 6.39 Estimated trends in maximum and mean diurnal temperature range 60 6.40 Annual values and long-term trends of sunshine and total rainfall 61 6.41 Annual values and long-term trends of minimum temperatures 62 6.42 Annual values and long-term trends of maximum temperatures 62 6.43 Annual values and long-term trends of mean and minimum relative humidity 63

6.44 Annual values and long-term trends of the mean diurnal temperature range and total annual potential evaporation

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Chapter 6

Analysis of climatic conditions Ground truth records, satellite info, and sea surface temperatures (SSTs) are processed to determine changes in climatic patterns. Analyses are conducted for three spatial scales: nationwide, regional, and local climatic conditions. On the nationwide level, only exploratory analyses are conducted to detect trends in the mean of historical time series of near-surface mean annual temperatures and total annual rainfall amounts. Observed trends are presented spatially. On the regional scale, weather stations located along a 5°N latitudinal cross section are selected for the analyses. The zonal transect is defined between approximately 72°W (Colombian Eastern plains) and 77°W (Colombian Pacific Coast), and by assuming different meridional widths. Annual cycles of mean ambient temperatures and rainfall amounts are estimated. Also, exploratory analyses are conducted to detect potential trends in monthly and annual records. Regional rainfall and temperature conditions are displayed over the 5°N latitudinal transect. On the local scale, analyzed records include cloud characteristics and meteorological records. Four cloud characteristics (optical thickness, cloud amount, top pressure, and top temperature) are selected for the analyses. Sea surface temperatures are also considered in order to explore links to cloud amounts over the high altitude area. Correlation analyses between cloud cover and SSTs observed in El Nino 3.4 region are conducted. Analyses include three different time-lags: 0, 1, and 2 months. Empirical Orthogonal Function modes and Principal Components (PC) are determined for January, February, July, and August SST anomalies. Simple correlation analyses between cloud amount anomalies and the first two obtained PCs are subsequently conducted. Fourier analyses are also performed to determine the underlying structures and compositions of cloud characteristics. The most powerful frequencies and their respective periods are calculated for each historical time series. Meteorological data (sunshine, rainfall, minimum temperature, maximum temperature, relative humidity, diurnal temperature range, potential evaporation, dew point, vapor pressure, cloud cover, and wind speed/direction) observed at stations located in the spatial domain (04°25’N-05°15’N and 75°00’W-76°00’W) are also selected to conduct the analyses of local conditions. Annual and monthly records include some or all of the following time series when data are available on a daily timescale:

− Sunshine: total sunshine; total number of foggy and sunny days; maximum, mean and minimum daily sunshine; and standard deviation of daily sunshine records.

− Rainfall: total rainfall amounts; total number of dry days; and maximum daily rainfall records. − Temperature: minimum, mean and maximum values under average conditions; minimum, mean

and maximum values during the coldest and the warmest days; and standard deviation of daily minimum, mean and maximum temperatures.

− Diurnal temperature range: minimum, mean and maximum diurnal temperature range; and day-to-day standard deviation of diurnal temperature range.

− Relative humidity: minimum, mean and maximum relative humidity values; and standard deviation of daily records.

− Other climatic variables: total potential evaporation, mean dew point, mean vapor pressure, mean cloud cover, and mean wind speed/direction.

Basic statistics (sample size, sample mean, standard deviation, signal-to-noise ratio, range, and dynamic range) are calculated for annual and monthly climatic time series. Annual cycles are all estimated for 'average' conditions using the historical time series. In general, the discussion on annual cycles includes either a gridded representation or a specific weather station. The following structure is

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used to display the network of met stations and the analysis of annual cycles (see notation of met station in section 6.3.1):

Lt/Ln 76°00’-75°50’ 75°50’-75°40’ 75°40’-75°30’ 75°30’-75°20’ 75°20’-75°10’ 75°10’-75°00’ 05°10’-05°15’ 7 10

05°00’-05°10’ 2 9, XV XI, XIV 3, 11, XXIV,

XXV II

04°50’-05°00’ 1, 8 III, IV, V, XII,

XIII, XVI, XVIII, XX, XXI

I, X, XXVI 5 6, XIX

04°40’-04°50’ VI, XVII XXII 4, XXIII 04°30’-04°40’ VII VIII 04°25’-04°30’ IX

Exploratory analyses are initially conducted to detect potential trends in monthly and annual records. Observed trends (observatory analysis) in temperatures, sunshine, rainfall, evaporation, and relative humidity are spatially represented. Also, non-homogeneities in annual time series of meteorological data are explored through confirmatory analyses. They include statistical test to detect changes in the variance and the mean (with known and unknown points of change), and significant trends. Abbe’s criterion for homogeneity and Petit and Cumulative Sums statistical tests are implemented to detect non-stationarities in historical time series when points of change are unknown. Bayesian analysis is used to estimate the distributions of the point of change and amount of change. Abrupt changes in the variance of hydrological time series are detected using the Simple F Test, the Simple F Test with corrections for dependence, the Modified F Test (using both Chi-square and F distributions), the Ansari-Bradley Test, the Bartlett Test, and the Levene Test, all conducted at a 0.05 significance level and performed for the points of change estimated by the Bayesian Analysis. Abrupt changes in the mean of the time series are detected through the implementation of the Mann-Whitney/Wilcoxon Rank Sum Test, the Simple t-Test (assuming change and no change in the variance), the Modified t-Test (assuming change and no change in the variance), the Simple t-Test with corrections for dependence (assuming change and no change in the variance), and the Kruskal-Wallis Test. All these tests are conducted at a 0.05 significance level and for the points of change estimated by the Bayesian Analysis. Trends in the historical time series (free of seasonality) are detected using the t-Test for the detection of linear trends, the Hotelling-Pabst Test, the Man-Kendall Test, and the Sen Test, all conducted at a 0.05 significance level. Statistically significant trends are then presented graphically for the selected spatial domain. Finally, annual values and long-term trends of sunshine, rainfall, minimum temperatures, maximum temperatures, relative humidity, diurnal temperature range, and potential evaporation are plotted versus altitude in order to explore potential mechanisms. This chapter summarizes our major findings on the changing climatic conditions. The first section deals with the results for the nationwide scale. The second section describes the evidence for the regional scale. The third part explores in detail the available info for the analysis of local conditions, as well as the observed climatology and historical trends.

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6.1. Nationwide scale Columns (1) and (2) of Table 6.1 summarize the weather stations deployed in Colombia, according to the 1996 database of the Institute of Hydrology, Meteorology and Environmental Studies (IDEAM). A total number of 7,386 met stations have been installed by Colombian met services. They have been divided into the following 13 categories: AM, CO, CP, LG, LM, ME, MM, NV, PG, PM, RS, SP, and SS stations; 10 of these categories are briefly described below. − 41 agromet stations (AM) have been installed by agriculture and irrigation offices to

simultaneously collect meteorological and biological information. AM stations provide local weather and agricultural advices to farmers and other end-users.

− A total number of 822 stations are ordinary climatological stations (CO). These stations collect daily values of minimum, maximum and mean temperatures, as well as total daily rainfall and mean daily relative humidity.

− 169 met stations are considered primary climatological stations (CP). Besides temperature, rainfall and relative humidity, CP stations measure sunshine, evaporation, cloudiness, wind speed, and wind direction.

− A total number of 852 stations are limnigraphic stations (LG). They continuously monitor river discharges and provide several other variables such as sediment loads.

− 1,402 stations are considered limnimetric stations (LM). They provide river discharges on a daily time scale.

− A total number of 501 pluviograph stations (PG) collect rainfall totals on timescales as short as 5-10 min.

− 3,389 met stations are considered pluviometric (PM). These collectors provide rainfall totals on a daily time scale.

− Finally, 36 primary synoptic stations (SP) and 24 secondary synoptic stations (SS) have been in total deployed in the Colombian airports. SP and SS stations collect daily values of minimum, maximum and mean temperatures, total daily rainfall, mean daily relative humidity, sunshine, evaporation, cloudiness, wind speed, and wind direction.

Figures 6.1(A) to 6.1(H) depict the spatial distribution of AM, CO, CP, ME, PG, PM, SP, and SS met stations, respectively. Even though the hydrometeorological network is significantly dense in the Andean region, few weather stations are located at higher altitudes (see Figure 6.2 for met stations located above 3,200 m). Columns (3), (4), (5), and (6) of Table 6.1 summarize those stations located above 3,200 m, 3,600 m, 4,100 m, and 4,500 m, respectively. These altitudes correspond to the transitions between life zones in Andean high mountain regions. The IDEAM provided data of monthly rainfall totals for a total number of 426 met stations and for the homogeneous period from January, 1981 through December, 2005. Columns (3) and (4) of Table 6.2 summarize the number of stations finally received and the respective proportions of the total number of installed stations. Figures 6.1(I) to 6.1(P) depict the spatial distributions of this sample. The IDEAM also provided data of monthly mean temperatures for a total number of 159 stations and for the period from January, 1930 through December, 2007 (longest historical period available in the dataset). Columns (5) and (6) of Table 6.2 summarize the received stations and their respective proportions. Figures 6.1(Q) to 6.1(V) depict the spatial distributions of the sample. Finally, Figure 6.3 depicts the trends observed in the historical time series of total annual rainfall and mean annual temperature on a nationwide scale.

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Table 6.1. Colombian hydrometeorological network

(1) Met Station

Type

(2) Total

IDEAM

(3) Total above

3,200 m

(4) Total above

3,600 m

(5) Total above

4,100 m

(6) Total above

4,500 m

Total 7,386 120 35 10 5

AM 41 0 0 0 0 CO 822 13 3 2 1 CP 169 2 1 1 0 LG 852 1 0 0 0 LM 1,402 16 0 0 0 ME 137 21 11 7 4 MM 6 0 0 0 0 NV 0 0 0 0 0 PG 501 7 2 0 0 PM 3,389 59 18 0 0 RS 6 0 0 0 0 SP 36 1 0 0 0 SS 24 0 0 0 0

Table 6.2. Available info from the Colombian hydrometeorological network

(1) Met

Station

(2) Total

IDEAM

(3) Total available

(Monthly rainfall)

(4) Sample (%) (Monthly rainfall)

(5) Total available

(Monthly temperature)

(6) Sample (%) (Monthly

temperature)

Total 7,386 426 -- 159 --

AM 41 16 39 14 34 CO 822 96 12 74 9 CP 169 36 21 31 18 LG 852 -- -- -- -- LM 1,402 -- -- -- -- ME 137 11 8 1 0.7 MM 6 0 0 0 0 NV 0 -- -- -- -- PG 501 31 6 -- -- PM 3,389 196 6 -- -- RS 6 0 0 0 0 SP 36 29 81 29 81 SS 24 11 46 9 38

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Type Total installed Available monthly rainfall Available monthly temperature

AM

EQ

05

10

Caribbean Sea

Pacific Ocean

PERU

BRAZIL

ECUADOR

VENEZUELA

COLOMBIA

80 65

LAT [°N]

LONG [°W] (A)

EQ

05

10

Caribbean Sea

Pacific Ocean

PERU

BRAZIL

ECUADOR

VENEZUELA

COLOMBIA

80 65

LAT [°N]

LONG [°W] (I)

EQ

05

10

Caribbean Sea

Pacific Ocean

PERUBRAZIL

ECUADOR

VENEZUELA

COLOMBIA

80 65

LAT [°N]

LONG [°W] (Q)

CO

EQ

05

10

Caribbean Sea

Pacific Ocean

PERUBRAZIL

ECUADOR

VENEZUELA

COLOMBIA

80 65

LAT [°N]

LONG [°W] (B)

EQ

05

10

Caribbean Sea

Pacific Ocean

PERUBRAZIL

ECUADOR

VENEZUELA

COLOMBIA

80 65

LAT [°N]

LONG [°W] (J)

EQ

05

10

Caribbean Sea

Pacific Ocean

PERUBRAZIL

ECUADOR

VENEZUELA

COLOMBIA

80 65

LAT [°N]

LONG [°W] (R)

CP

EQ

05

10

Caribbean Sea

Pacific Ocean

PERUBRAZIL

ECUADOR

VENEZUELA

COLOMBIA

80 65

LAT [°N]

LONG [°W] (C)

EQ

05

10

Caribbean Sea

Pacific Ocean

PERUBRAZIL

ECUADOR

VENEZUELA

COLOMBIA

80 65

LAT [°N]

LONG [°W] (K)

EQ

05

10

Caribbean Sea

Pacific Ocean

PERU

BRAZIL

ECUADOR

VENEZUELA

COLOMBIA

80 65

LAT [°N]

LONG [°W] (S)

ME

EQ

05

10

Caribbean Sea

Pacific Ocean

PERU

BRAZIL

ECUADOR

VENEZUELA

COLOMBIA

80 65

LAT [°N]

LONG [°W] (D)

EQ

05

10

Caribbean Sea

Pacific Ocean

PERU

BRAZIL

ECUADOR

VENEZUELA

COLOMBIA

80 65

LAT [°N]

LONG [°W] (L)

EQ

05

10

Caribbean Sea

Pacific Ocean

PERUBRAZIL

ECUADOR

VENEZUELA

COLOMBIA

80 65

LAT [°N]

LONG [°W] (T)

Figures 6.1(A) to 6.1(V). Colombian hydrometeorological network and available met stations

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Type Total installed Available monthly rainfall Available monthly temperature

PG

EQ

05

10

Caribbean Sea

Pacific Ocean

PERU

BRAZIL

ECUADOR

VENEZUELA

COLOMBIA

80 65

LAT [°N]

LONG [°W] (E)

EQ

05

10

Caribbean Sea

Pacific Ocean

PERU

BRAZIL

ECUADOR

VENEZUELA

COLOMBIA

80 65

LAT [°N]

LONG [°W] (M)

PG met stations do not collect temperatures

PM

EQ

05

10

Caribbean Sea

Pacific Ocean

PERU

BRAZIL

ECUADOR

VENEZUELA

COLOMBIA

80 65

LAT [°N]

LONG [°W] (F)

EQ

05

10

Caribbean Sea

Pacific Ocean

PERU

BRAZIL

ECUADOR

VENEZUELA

COLOMBIA

80 65

LAT [°N]

LONG [°W] (N)

PM met stations do not collect temperatures

SP

EQ

05

10

Caribbean Sea

Pacific Ocean

PERU

BRAZIL

ECUADOR

VENEZUELA

COLOMBIA

80 65

LAT [°N]

LONG [°W] (G)

EQ

05

10

Caribbean Sea

Pacific Ocean

PERU

BRAZIL

ECUADOR

VENEZUELA

COLOMBIA

80 65

LAT [°N]

LONG [°W] (O)

EQ

05

10

Caribbean Sea

Pacific Ocean

PERUBRAZIL

ECUADOR

VENEZUELA

COLOMBIA

80 65

LAT [°N]

LONG [°W] (U)

SS

EQ

05

10

Caribbean Sea

Pacific Ocean

PERU

BRAZIL

ECUADOR

VENEZUELA

COLOMBIA

80 65

LAT [°N]

LONG [°W] (H)

EQ

05

10

Caribbean Sea

Pacific Ocean

PERU

BRAZIL

ECUADOR

VENEZUELA

COLOMBIA

80 65

LAT [°N]

LONG [°W] (P)

EQ

05

10

Caribbean Sea

Pacific Ocean

PERUBRAZIL

ECUADOR

VENEZUELA

COLOMBIA

80 65

LAT [°N]

LONG [°W] (V)

Figures 6.1(A) to 6.1(V) (Cont.). Colombian hydrometeorological network and available met stations

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CO

CP

ME

PG

SP

PM

EQ

05

10

Caribbean Sea

Pacific Ocean

PERUBRAZIL

ECUADOR

VENEZUELA

COLOMBIA

80 65

LAT [°N]

LONG [°W]

Figure 6.2. Colombian met stations located above 3,200 m

Figure 6.3. Trends in historical time series (exploratory analyses) – nationwide scale. Left panel: trends in the historical time series of total annual rainfall amounts gathered at 426 met stations during the homogeneous period from January, 1981 through December, 2005. Right panel: trends in the historical time series of mean annual temperature gathered at 159 met stations.

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6.2. Regional scale A total number of 61 met stations, which are reporting monthly rainfall totals and where datasets are available (see analysis of nationwide conditions), are located along the proposed 5°N latitudinal transect (see Table 6.3 and cross sections on Figures 6.4(A) to 6.4(H)).

Table 6.3. Met stations reporting monthly rainfall and located along the 5°N latitudinal transect

Met Stations Transect Total number Met

Stations Transect Total

number

AM 4.0-6.0 N 4 PG 4.5-5.5 N 9 CO 4.8-5.2 N 9 PM 4.8-5.2 N 17 CP 4.5-5.5 N 7 SP 4.5-5.5 N 4 ME 4.7-5.3 N 7 SS 4.0-6.0 N 4

A total number of 28 met stations, which are reporting monthly ambient temperatures and where datasets are available, are located along the 5°N latitudinal transect (see Table 6.4 and cross sections on Figures 6.5(A) to 6.5(E)).

Table 6.4. Met stations reporting monthly temperature and located along the 5°N latitudinal transect

Met Stations Transect Total number Met Stations Transect Total

number

AM 4.0-6.0 N 5 PG 4.5-5.5 N -- CO 4.8-5.2 N 7 PM 4.8-5.2 N -- CP 4.5-5.5 N 10 SP 4.5-5.5 N 5 ME 4.7-5.3 N -- SS 4.0-6.0 N 1

Figures 6.6 and 6.7 show the observed trends in the historical time series of total annual rainfall and mean annual temperature, respectively, gathered at weather stations located along the 5°N-latitudinal transect. Trends in rainfall (increasing/decreasing) are expressed in %/decade; trends in temperature (increasing/decreasing) are expressed in °C/decade.

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8007006005004003002001000

0

1,000

2,000

3,000

z [m

]

0

1,000

2,000

3,000

z [m

]

D [km]

8007006005004003002001000

0

1,000

2,000

3,000

z [m

]

0

1,000

2,000

3,000

z [m

]

D [km]

(AM)

211

8502

2120

542

2403

512

350

2502

4-6 °N

(A)

8007006005004003002001000

0

1,000

2,000

3,000

z [m

]

0

1,000

2,000

3,000

z [m

]

D [km]

8007006005004003002001000

0

1,000

2,000

3,000

z [m

]

0

1,000

2,000

3,000

z [m

]

D [km]

(CO)

212

0598

2306

512

2613

510

2614

503

2615

517

350

8504

3508

505

351

950254

0250

1

4.8-5.2 °N

(B)

8007006005004003002001000

0

1,000

2,000

3,000

z [m

]

0

1,000

2,000

3,000

z [m

]

D [km]

8007006005004003002001000

0

1,000

2,000

3,000

z [m

]

0

1,000

2,000

3,000

z [m

]

D [km]

(CP)

2120

62221

2550

8

2401

512

2611

504

3507

502

3507

504

3509

511

4.5-5.5 °N

(C)

8007006005004003002001000

0

1,000

2,000

3,000

z [m

]

0

1,000

2,000

3,000

z [m

]D [km]

8007006005004003002001000

0

1,000

2,000

3,000

z [m

]

0

1,000

2,000

3,000

z [m

]D [km]

(ME)

2120

589

212

0592

2120

596

*

* & 2120602 & 2120621

2120

606

(NO

) 21

2451

4

4.7-5.3 °N

(D)

8007006005004003002001000

0

1,000

2,000

3,000

z [m

]

0

1,000

2,000

3,000

z [m

]

D [km]

8007006005004003002001000

0

1,000

2,000

3,000

z [m

]

0

1,000

2,000

3,000

z [m

]

D [km]

(PG)

2120

160

2120

163

2120

164

*

2121

002

2125

007

(NO

) 23

020

08

3507

001

* & 3507023

3507

026

4.5-5.5 °N

(E)

8007006005004003002001000

0

1,000

2,000

3,000

z [m

]

0

1,000

2,000

3,000

z [m

]

D [km]

8007006005004003002001000

0

1,000

2,000

3,000

z [m

]

0

1,000

2,000

3,000

z [m

]

D [km]

(PM)

2120

016

2120

062

2120

121

2120

155

2123

009

2125

011

(NO

) 21

2504

52125

050

2306

019

2306

026

2614

009

2614

018

2615

006

3507

008

350

7010

350

7021

350

8007

4.8-5.2 °N

(F) Figures 6.4(A) to 6.4(H). Available met stations reporting monthly rainfall and located along the 5°N latitudinal transect. x-axis depicts the distance from the Pacific Coast. Arrowheads point the altitude of met stations.

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8007006005004003002001000

0

1,000

2,000

3,000z

[m]

0

1,000

2,000

3,000

z [m

]

D [km]

8007006005004003002001000

0

1,000

2,000

3,000z

[m]

0

1,000

2,000

3,000

z [m

]

D [km]

(SP)

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CP SP

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Figure 6.6. Regional rainfall conditions along the 5°N latitudinal transect; only the Western and Central mountain ranges are presented (transect is shown for the interval 50-300 km). Top panel: Location of available weather stations; Center panel: Total annual rainfall (amounts on the right y-axis) and confidence intervals for a 0.05 significance level; Bottom panel: Observed trends in historical time series.

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Γ= -6.9°C/km

Γ= -6.0°C/km

Γ= -7.6°C/km

Figure 6.7. Regional temperature conditions along the 5°N latitudinal transect; only the Western and Central mountain ranges are presented (transect is shown for the interval 50-300 km). Top panel: Location of available weather stations; Center panel: Mean annual temperatures (values on the right y-axis), confidence intervals for a 0.05 significance level, and environmental lapse rates; Bottom panel: Observed trends in historical time series. 6.3. Local scale 6.3.1. Available info Data of sea surface temperatures (SSTs) for the analysis of local conditions: two regions in the tropical belt 30°S-30°N have been considered for the analyses of SSTs: the Indo-Pacific region, which extends from 30°E to 70°W, and the Tropical Atlantic Ocean, which extends from 60°W to almost 16°E (see Figure 6.8). Spatially-distributed monthly sea surface temperatures (SST) of the tropical Indo-Pacific region for the spatial domain [30°E-90°W and 30°S-30°N] and for the time period from January, 1942 to December, 2007 (Kaplan et al., 1998; Reynolds and Smith, 1994) were selected for the analyses. See Figure 6.8. Data can be downloaded from the Data Library of the International Research Institute for Climate and Society, IRI (http://iri.columbia.edu/; source of info: Kaplan Extended v2). Analyses also included a narrower region [30°E-90°W and 15°S-15°N] for the same historical period. During the available timespan very strong unusual warming of SSTs associated with strong El Niño events were observed over the Eastern Tropical Pacific in, particularly, the years 1982-83 and 1997-98, and mainly during the months of January of El Niño+1 year. On the contrary, strong La Niña cold events observed during the years 1973-74 and 1975-76 were accompanied by unusual cooling of the Tropical Pacific. Monthly SST data of the Tropical Atlantic Ocean for the spatial domain [60°W-16°E and 19°S-29°N] and for the time period from January, 1964 to December, 2007 were also included (Data are available in IRI Data Library; source of info: Fundação Cearense de Meteorologia e Recursos Hídricos - FUNCEME). Finally, historical time series of mean monthly SSTs observed in El Nino 3.4 region for the period from January, 1950 through August, 2005 are also processed to support statistical tests.

19

Figure 6.8. Data of sea surface temperatures (SSTs) for the analysis of local conditions. Top panel: January air-sea net heat flux observed under normal conditions over the spatial domain [30°E-0°E/W and 30°S-30°N] (Josey et al., 1999; source of info: Southampton Oceanography Centre). Bottom panel: Sea surface temperature anomalies observed in January, 1992 over the spatial domain [30°E-90°W and 30°S-30°N]. Data of cloud characteristics for the analysis of local conditions: Several cloud characteristics (cloud amount, top pressure, top temperature, and optical thickness for multiple clouds; see Figure 6.9), previously discussed by Ruiz et al. (2008), are re-processed for the grid point 3556 (03°45’N; 76°15’W). Data can be downloaded from the Data Library of the International Research Institute for Climate and Society, IRI (http://iri.columbia.edu/).

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Figure 6.9. Cloud characteristics for multiple clouds –optical thickness (left panel) and cloud amount (right panel)– for the grid point 3556.

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Figure 6.9 (Cont.). Cloud characteristics for multiple clouds –top pressure (left panel), and top temperature (right panel)– for the grid point 3556. Ground truth data: A total number of 363 weather stations have been installed in the selected spatial domain, but only 251 still collect climatic data (see Table 6.5).

Table 6.5. Hydrometeorological network available in the spatial domain 04°25’-05°15’N and 75°00’-76°00’W

Met station type Total IDEAM Total still collecting data Total 363 251

AM 0 0 CO 63 29 CP 10 9 ME 27 8 MM 0 0 NV 0 0 PG 31 23 PM 227 178 RS 0 0 SP 4 3 SS 1 1

30 weather stations are initially used to characterize local climatic conditions (see tables 6.6, 6.7, and 6.8). 11 of them, denoted hereafter 1 to 11 (see Table 6.6), are chosen among the regional stations located along the 5°N latitudinal transect. Various time series are updated with longer time periods, as discussed later.

Table 6.6. Regional stations included in the analysis of local conditions

N Met Station Latitude [N]

Longitude [W]

Altitude [m]

Dataset(s) and available period(s) Type ID Name

1 CO 2613510 La Bohemia 04 53 75 55 1,020 TMR

(Oct/63-Dec/05)

2 CO 2614503 La Camelia 05 03 75 52 1,670

TMR (Jan/81-Sep/04)

MMT (Jan/64-Sep/04)

3 CO 2615517 Fca Tesorito 05 02 75 27 2,200 TMR

(Sep/93-Dec/05)

4 PG 2121002 Las Juntas 04 43 75 19 1,765 TMR

(Jan/81-Dec/05)

5 PM 2125011 Murillo 04 52 75 11 2,960 TMR

(Jan/63-Dec/90)

21

N Met Station Latitude [N]

Longitude [W]

Altitude [m]

Dataset(s) and available period(s) Type ID Name

6 PM 2125050 Libano 04 56 75 04 1,585 TMR

(Jan/63-Dec/79)

7 PM 2614009 Taparcal 05 10 75 52 1,520 TMR

(Jan/81-Dec/05)

8 PM 2614018 La Virginia-Alerta 04 54 75 53 900 TMR

(Apr/79-Dec/05)

9 PM 2615006 Arauca 05 07 75 42 890 TMR

(Jan/63-Dec/05)

10 CO 2302501 Llanadas 05 12 75 08 1,420 MMT

(Apr/56-Nov/94)

11 SP 2615511 Apto La Nubia 05 02 75 28 2,080 MMT

(Apr/56-Nov/94) TMR: Total Monthly Rainfall (mm); MMT: Mean Monthly Temperature (°C)

11 met stations, denoted hereafter I to XI (see Table 6.7 and Figure 6.10), are located in the surroundings of the high mountain basin of the Claro River. Some of them (I, and III to IX) were previously selected and processed by Ruiz et al. (2008) to conduct their analyses.

Table 6.7. Met stations operated by Instituto de Hidrología, Meteorología y Estudios Ambientales (IDEAM) and Central Hidroeléctrica de Caldas-CHEC

Source: *World Meteorological Association-WMO (data can be downloaded from the IRI’s Data Library), &HidroSig Java-PARH/UNALMED, %Subdirección de Hidrología e Instrumentación-IDEAM, and ΨCHEC

N ID Name Lat [N]

Lon [W]

Alt [m] Climatic variable Available period

I 2615515 BRISAS LAS 04°56' 75°21’ 4,150

Mean daily T –estimated– (°C)

13/Oct/81-31/Oct/03

Minimum daily T (°C) 13/Oct/81-31/Oct/03

Maximum daily T (°C) 13/Oct/81-31/Oct/03 Diurnal T range –estimated– (°C)

13/Oct/81-31/Oct/03

Total daily rainfall (mm)

12/Oct/81-30/Oct/03

Mean daily relative humidity (%)

13/Oct/81-31/Oct/03

Total daily sunshine (hours)

01/Jan/82-30/Nov/05

II 2125512 VILLAHERMOSA 05°02' 75°07’ 2,029

Minimum daily T (°C) 01/Apr/78-29/Dec/05 Maximum daily T (°C) 01/Apr/78-28/Dec/05

Diurnal T range –estimated– (°C)

01/Apr/78-28/Dec/05

Total daily rainfall (mm) 03/Sep/75-30/Jun/05 Mean daily relative humidity

(%) 01/Dec/77-28/Dec/05

Total daily sunshine (hours) 21/Apr/79-08/Jul/94

III* WMO

8014902 CHINCHINA 5.0 75.6 1,360

MMT Jan/51-Dec/70

TMR Jan/51-Dec/70

IV* WMO

8014904 CHINCHINA 5.0 75.6 1,360

MMT Jan/51-Dec/70

TMR Apr/50-Dec/79

V* WMO

8014911 CHINCHINA 5.0 75.6 1,310

MMT Jan/71-Dec/80

TMR Jan/71-Dec/80

VI&

WMO 8021000

IDEAM 2613504

WMO PEREIRA

MATECANA

IDEAM

04°49' 75°44' 1,342

MMT Sep/47-Apr/05

Minimum monthly T (°C) Jan/59-Dec/95

TMR Jan/47-Sep/96 Total monthly potential

Evaporation (mm) Jan/77-Dec/95

22

N ID Name Lat [N]

Lon [W]

Alt [m]

Climatic variable Available period

APTO MATECANA

Monthly dew point (°C) Jan/49-Dec/94 Vapor pressure

(10^2*kg/m/s^2) Jan/47-Dec/95

Relative humidity –inferred– (%) Jan/48-Dec/95

VII %

WMO 8021100

IDEAM 2612506

WMO ARMENIA EL EDEN

IDEAM APTO

EL EDEN

04°27' 75°46’ 1,204

Mean daily T (°C) 02/Jan/78-30/Apr/07

Minimum daily T (°C) 02/Jan/78-30/Apr/07 Maximum daily T (°C) 02/Jan/78-30/Apr/07

Diurnal T range –estimated– (°C)

02/Jan/78-30/Apr/07

Total daily rainfall (mm) 01/Apr/49-12/Dec/07

VIII* WMO

8021101 EL PASO 4.5 75.6 3,264 TMR Jan/50-Dec/79

IX* WMO

8021400 IBAGUE PERALES

4.4 75.1 928 TMR Jan/55-Dec/93

XΨ CHEC 6-9009

Montenegro 04°57’ 75°28’ 2,600 Total daily rainfall (mm) 30/Nov/63-30/Jun/06

XI% City Manizales 5.07 75.52 2,150 m MMT Jan/56-Dec/94 TMR: Total Monthly Rainfall (mm); MMT: Mean Monthly Temperature (°C)

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4% / decade

Figure 6.10. Example of time series of total monthly rainfall for the analysis of local conditions: met stations IV-8014904 CHINCHINA and VIII-8021101 EL PASO The Villahermosa station (II) is located on the East flank of the Andean Central Mountain Range, and is included in the analyses to assess the differences between the western and eastern slopes of the cordillera. Stations III to IX constitute the dataset of the regional GHCN (Global Historical Climatic Network) monitored by the World Meteorological Organization. Data for the synoptic met station Aeropuerto Matecana (station VI), located in the city of Pereira, Department of Risaralda, are complemented with records of total monthly rainfall, mean and minimum monthly temperatures, total monthly evaporation, mean monthly dew point, and mean monthly vapor pressure for the period from January, 1947 through December, 1995. Apto Matecana (VI) was also included in the analysis of regional conditions described above. Data for the synoptic met station Aeropuerto El Eden (station VII), located in the city of Armenia, Department of Quindio, are complemented with records of minimum, mean and maximum daily temperatures, as well as total daily rainfall for the periods from January, 1978 through April, 2007 and from April, 1949 through December, 2007, respectively. Data for the synoptic met station Aeropuerto Perales (station IX), located in the city of Ibague, Department of Tolima, are complemented with records of total monthly rainfall for the periods from January, 1981 through February, 1986 and January, 1994 through December, 2005. Two additional weather stations (X and XI) are included in the analysis of local conditions: the Central Hidroeléctrica de Caldas-CHEC provided total daily rainfall records from the pluviometric station 6-9009 Montenegro, located in the municipality of Villamaria,

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Department of Caldas; and mean monthly temperatures observed in the city of Manizales are processed for the period from January, 1956 through December, 1994. Finally, 8 met stations, denoted hereafter XII to XIX, are selected among the database administered by the Centro Nacional de Investigaciones de Café, Cenicafé (see Table 6.8). Weather stations named Cenicafe (XII), Naranjal (XIII), and Agronomia (XIV) were also part of the analysis of regional conditions.

Table 6.8. Met stations administered by Federación Nacional de Cafeteros de Colombia (Cenicafé) Source: Archivos Climáticos, Grupo Disciplina de Agroclimatología, Cenicafé (Chinchiná, Caldas, Colombia)

N ID Name Latitude [N]

Longitude [W]

Altitude [m] Climatic variable Available period

(monthly timescale)

XII 2615502 Cenicafé 04°59'N 75°36'W 1,310

Total daily rainfall (mm) Jan/42-Dec/06 Total daily sunshine (h) Jan/61-Dec/07

Daily maximum temperatures (°C) Jan/50-Dec/07

Daily minimum temperatures (°C) Jan/50-Dec/07

Mean daily temperatures (°C) Jan/50-Dec/07 Mean daily relative humidity (%) Jan/50-Dec/07

XIII 2613505 Naranjal 04°58'N 75°39'W 1,381

Total daily rainfall (mm) Jan/56-Dec/06

Total daily sunshine (h) Jan/56-Dec/07



Mean daily temperatures (°C) Jan/56-Dec/07

Mean daily relative humidity (%) Jan/90-Dec/07

XIV 2615505 Agronomía 05°03'N 75°30'W 2,088







XV 2615509 Santágueda 05°04'N 75°40'W 1,026







XVI 2613507 El Cedral 04°52'N 75°32'W 2,120




Daily minimum temperatures (°C) Jan/61-Dec/06 Mean daily temperatures (°C) Jan/61-Dec/06


XVII 2612524 La Catalina 04°45'N 75°44'W 1,321







XVIII 2613506 El Jazmín 04°55'N 75°37'W 1,635

Total daily rainfall (mm) Jan/60-Dec/07 Total daily sunshine (h) Jan/61-Dec/07



Mean daily temperatures (°C) Jan/75-Dec/06 Mean daily relative humidity (%) Jan/90-Dec/06

24

N ID Name Latitude [N]

Longitude [W]

Altitude [m]

Climatic variable Available period (monthly timescale)

XIX 2125513 La Trinidad 04°54'N 75°02'W 1,453







Figure 6.11 depicts the observed trends (observatory analysis) in minimum, mean, and maximum temperatures, as well as mean diurnal temperature range gathered by the weather stations 1 to 11 and I to XI. Figure 6.12 depicts the trends in total annual sunshine, total annual rainfall, total annual potential evaporation, and mean annual relative humidity observed at the same group of met stations. A narrower spatial domain (04°40’N-05°10’N and 75°10’W-75°40’W) is proposed to consider additional weather stations (see Table 6.9), all of them operated by the IDEAM. A total number of 12 met stations were installed (and are still gathering data) in this spatial domain, but 3 of them are not available and 2 were previously considered in the analysis of regional and local conditions (2125011 Murillo and 2615511 Apto La Nubia). Then, this dataset provides 7 additional weather stations, named XX to XXVI (see Table 6.9). Data for the PM met station 2125011 Murillo are complemented with records of: (a) total monthly rainfall for the periods from March, 1960 through December, 1962 and from January, 1991 through December, 2007; (b) maximum daily rainfall per month for the period from March, 1960 through December, 2007; and (c) –estimated– monthly total dry days for the period from March, 1960 through December, 2007. Data for the SP met station 2615511 Apto La Nubia are complemented with records of: (i) total monthly rainfall for the period from June, 1968 through April, 2006; (ii) maximum daily rainfall per month for the period from June, 1968 through April, 2006; (iii) –estimated– monthly total dry days for the period from June, 1968 through April, 2006; (iv) minimum, mean and maximum monthly temperatures for the period from February, 1969 through April, 2006; (v) mean monthly relative humidity for the period from February, 1969 through April, 2006; (vi) total monthly evaporation for the period from February, 1971 through April, 2006; (vii) total monthly sunshine for the period from November, 1970 through December, 2007; (viii) mean monthly cloud cover for the period from February, 1969 through April, 2006; and (ix) mean monthly wind speed and direction for the period from June, 1976 through December, 1986. Figure 6.13 depicts the final sample of met stations selected for the analysis of local conditions. A total number of 37 weather stations [Stations 1 to 11 (11 in total); stations I to XI (11 in total); stations XII to XIX (8 in total); and stations XX to XXVI (7 in total)] are available to assess possible changes in climatic conditions in the area.

25

75°20’75°30’ 75°10’75°40’75°50’

04°50’

04°40’

04°30’

05°00’

05°10’

III, IV and V

VI

VII

VIIIIX

LONGITUDE [W]

LA

TIT

UD

E [

N]

II

X

XI

Ψ

I

1

2

4

5

6

7

8

9

°C/decade

Min Mean

Max DTR

NO TRENDΨ

0.4+0.2

°C/decade

1.2

-0.4-0.2 -1.2

10

3

11

Ψ

Figure 6.11. Observed trends (observatory analysis) in minimum (top left quadrant), mean (top right quadrant), and maximum temperatures (bottom left quadrant), and mean diurnal temperature range (bottom right quadrant). Circles denote the location of weather stations; red dots depict increasing trends; black dots depict decreasing trends; yellow solid line delineates the perimeter of the Los Nevados Natural Park; grey solid line shows the Claro River’s high altitude basin.

75°20’75°30’ 75°10’75°40’75°50’

04°50’

04°40’

04°30’

05°00’

05°10’

LONGITUDE [W]

LA

TIT

UD

E [

N]

II

X

VI

VII

VIIIIX

XI

Ψ Ψ

Ψ

I

III, IV and V

1

2

4

7

5

6

8

9

%/decade

SR R

EVP RH

NO TRENDΨ

+4<+3

%/decade

+8

-4<-3 -8

10

3

11

Figure 6.12. Observed trends (observatory analysis) in total annual sunshine (top left quadrant), total annual rainfall (top right quadrant), total annual potential evaporation (bottom left quadrant), and mean annual relative humidity (bottom right quadrant). Circles denote the location of weather stations; red dots depict increasing trends; black dots depict decreasing trends; the yellow solid line delineates the perimeter of the Los Nevados Natural Park; the grey solid line shows the Claro River’s high altitude basin.

26

Table 6.9. Hydrometeorological network available in the spatial domain 04°40’-05°10’N and 75°10’-75°40’W and still collecting climatic data

Met station type

Total in the spatial domain

Total IDEAM and still

collecting data ID Name Latitude

[N] Longitude

[W] Altitude

[m] N

Total 78 12 7 in total

AM 0 0 -- -- -- -- --

CO 9 3 2613511 Veracruz 04°51’ 75°38’ 1,684 XX 2613516 San Remo 04°50’ 75°34’ 2,000 XXI 2613514 La Laguna 04°47’ 75°25’ 4,000 XXII

CP 3 0 -- -- -- -- -- ME 2 1 2124509 La Ermita 04°43’ 75°15’ 3,250 XXIII MM 0 0 -- -- -- -- -- NV 0 0 -- -- -- -- -- PG 5 0 -- -- -- -- --

PM 58 7

2615016 La Esperanza 05°01’ 75°21’ 3,240 XXIV

2302013 La Leonera 05°06’ 75°21’ 3,580 XXV 2616010 Neira 05°10’ 75°31’ 2,080 Not available 2615015 Papayal 04°57’ 75°29’ 2,220 XXVI 2613017 Potreros 04°54’ 75°33’ 2,140 Not available

2613006 Sub Sta Rosa 04°53’ 75°38’ 1,675 Not available

2125011 Murillo 04°52’ 75°11’ 2,960 5 (see ID in Table 6.6)

RS 0 0 -- -- -- -- --

SP 1 1 2615511 Apto La Nubia 05°02’ 75°28’ 2,080

11 (see ID in Table .6.6)

SS 0 0 -- -- -- -- --

Streamflow data: Table 6.10 presents the total number of limnigraphic (LG) and limnimetric (LM) stations available in the selected spatial domain. Although the network includes 90 stations, only 47 still measure river discharges.

Table 6.10. LG and LM stations available in the spatial domain 04°25’-05°15’N and 75°00’-76°00’W

Met station type Total installed Total still collecting data

Total 90 47

LG 25 12 LM 65 35

The IDEAM provided records for only those LG and LM stations described in Table 6.11. Since minimum, mean and maximum levels observed at stations 2613719 Buenos Aires (Otun River) and 2613721 La Pastora (Otun River) are only available for the periods 1994-2002 and 1994-1995, respectively, their records are not included in the analyses. Thus, only records of minimum, mean and maximum streamflows, observed at the LG stations 2615708 Chupaderos (Chinchina River) and 2613711 La Bananera 6-909 (Otun River), are processed for the analysis of local conditions. Their historical periods are, respectively, 1988-2005 and 1971-2005.

27

Table 6.11. LG and LM stations available in the spatial domain 04°40’-05°10’N and 75°10’-75°40’W and still

collecting data

Met station type

Total in the spatial domain

Total IDEAM and still collecting data ID Name

Latitude [N]

Longitude [W]

Altitude [m]

Total 24 4

LG 5 2 2615708

Chupaderos (Chinchina River) 05°03’ 75°31’ 2,040

2613711 La Bananera 6-909 (Otun River) 04°47’ 75°38’ 1,530

LM 19 2 2613721

La Pastora (Otun River) 04°43’ 75°31’ 2,450

2613719 Buenos Aires (Otun River) 04°44’ 75°35’ 1,920

75°20’75°30’ 75°10’75°40’75°50’

04°50’

04°40’

04°30’

05°00’

05°10’

VI

VII

VIIIIX

LONGITUDE [W]

LA

TIT

UD

E [

N]

II

X

XI

CHANGES IN TEMPERATURE CHANGES IN TEMPERATURE –– NEW ANALYSESNEW ANALYSES

°C/decade

Min Mean

Max DTR

NO TRENDΨ

I

1

2

4

5

6

7

8

9

XIIXIII

XIV

XV

XVI

XVII

XIX

0.2+0.1

°C/decade

>0.6

-0.2-0.1 >-0.6

10

3

11

XXXXI

XXII XXIII

XXIV

XXV

XXVIXVIII

III, IV and V

Figure 6.13. Sample of met stations selected for the analysis of local conditions. Stations 1 to 11 and I to XI are represented by white targets; stations XII to XIX are shown in blue targets; and stations XX to XXVI are highlighted in red.

28

6.3.2. Climatology Data of sea surface temperatures (SSTs) for the analysis of local conditions: according to the air-sea net heat flux climatology, maximum values of about +150 W/m2 are observed south of the Equator during the winter of the Northern Hemisphere-NH (trimester December-January-February, DJF). During the trimester June-July-August (JJA), summer in the Northern Hemisphere, maximum values of almost +180 W/m2 are observed in latitudes north (particularly at 30°N). Heat losses of about –150 W/m2 are reached in the subtropics of the NH and Southern Hemisphere during the trimesters DJF and JJA, respectively. SSTs in Nino 3.4 region exhibit an intra-annual cycle with a peak occurring during the months of April, May, and June, with temperatures reaching values of about 27.5°C. During the month of January, SSTs in this region tend to reach values of about 26.5°C under normal conditions, below the minimum threshold of 300 K necessary to initiate deep convection. During El Nino conditions, an increase of almost 0.6°C is generally observed throughout the year, with a maximum change of +0.8°C in the month of January. Data of cloud characteristics: Figure 6.14 depicts the annual cycles of all type cloud characteristics observed under normal conditions on the region.

0

50

100

150

200

250

300

350

01 02 03 04 05 06 07 08 09 10 11 12

Month

Tota

l mon

thly

sun

shin

e [h

rs]

5,0

5,5

6,0

6,5

7,0

7,5

8,0

8,5

9,0

9,5

10,0

Opt

ical

thic

knes

s

SR1 [hrs]

Optical Thickness

0

50

100

150

200

250

300

350

01 02 03 04 05 06 07 08 09 10 11 12

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Tota

l mon

thly

sun

shin

e [h

rs]

66

68

70

72

74

76

78

80

82

84

86

88

Clo

ud a

mou

nt 3

556

[%]

SR1 [hrs]

CA [%]

200

250

300

350

400

450

500

550

01 02 03 04 05 06 07 08 09 10 11 12

Month

Top

pres

sure

355

6 [m

b]

240

245

250

255

260

265

270

Top

tem

pera

ture

355

6 [K

]

Top pressure [mb]

Top temperature [K]

0

100

200

300

400

500

600

01 02 03 04 05 06 07 08 09 10 11 12Month

Tot

al m

onth

ly ra

infa

ll [m

m]

70

75

80

85

90

95

100M

ean

mon

thly

RH

[%]

R1 [mm]

ARH

Figure 6.14. Annual cycles of cloud characteristics for all type clouds –optical thickness (top left panel), cloud amount CA (top right), top pressure and top temperature (bottom left)– and for the grid point 3556. Annual cycles of total sunshine SR1 (top left and right panels), total rainfall and mean relative humidity (bottom right) for one of the longest historical periods available in the dataset (Station XII, 2615502 Cenicafe) are also displayed. Error bars indicate the confidence interval for a 0.05 significance level. The total amount of clouds observed over the region during the period from July, 1983 through August, 2001 suggests that under ‘average’ conditions the cloudiness patterns exhibit an intra-annual

29

cycle with two peaks: the first peak occurs during the trimester March-April-May (MAM) and exhibits an average cloud cover (all types) of about 84%; the second one falls in the trimester September-October-November (SON) and reaches a mean cloud amount of 83%. The trimesters DJF and JJA are characterized by low cloud amounts, reaching values as low as 76% (month of January). The annual cycle of cloud amount matches, as expected, the annual cycle of rainfall patterns (see top right and bottom right panels on Figure 6.14). The confidence intervals suggest a high variability of the total amount of clouds in the month of August. The minimum values (6.0 to 7.5) of the optical depth are observed over the months of May, June, and July; the maximum values (7.5 to 9.2) tend to occur in the months of November and December. Top temperatures during the trimester DJF increase to values in the range from 260 to 265 K; top pressures fluctuate between 450 and 500 mb. Top temperatures during the months of May, September and October (wet months) decrease to values in the range 250-255 K and top pressures fluctuate between 400 and 450 mb. Data of top pressure and top temperature suggest that during the trimester DJF a contraction of the column of clouds normally occurs. Conversely, during the months of May, September and October (wet months) the column of clouds expands and reaches higher levels in the atmosphere. Data of sunshine: Figures 6.15 to 6.18 depict the annual cycles of: total sunshine (SR1) and total foggy days (SR2); SR1 and total sunny days (TSD); daily maximum sunshine (SR4) and daily minimum sunshine (SR6); and daily mean sunshine (SR5) and standard deviation of daily sunshine (SR7), all of them observed in the selected spatial domain. Minimum and maximum values on SR1 bar plots are set to 0 and 360 hours/month (0 and 12 hours/day x 30 days/month, respectively). Min and max values on SR2 and TSD bar plots are set to 0 to 30 days/month. Finally, the range of SR4, SR5, SR6, and SR7 bar plots is defined to be 0-12 hours/day. Four particular patterns are observed in the annual cycles of the selected spatial domain: (a) the distributions at met stations located at lower levels on the Western flank of the Andean Central Mountain Range (ACMR) (they include those observed at stations XV, 11, XII, XIII, XVIII, XX, and XVII); (b) the annual cycles for the weather station XVI 2613507 El Cedral, depicted in Figure 6.19; (c) those estimated for the met station 1 Las Brisas, located at higher levels on the Western flank of the ACMR; and (d) those observed at lower levels on the Eastern flank of the ACMR (represented by met stations II and XIX). The weather stations located at lower levels on the Western flank of the ACMR exhibit bimodal intra-annual cycles of the total sunshine with peaks occurring during the trimesters DJF and JJA. The maximum total monthly sunshine values occurring during those seasons reach 170 and 160 hours/month, respectively. The total number of foggy days during the sunshine maxima reaches only 1 day/month; the total number of sunny days arrives to, consistently, 29-30 days/month. The sunshine minima are observed in the months of April-May (110-130 hours/month) and September-October (130-140 hours/month); during these periods, the total number of foggy days increases to 2 days/month, whereas the total number of sunny days decreases to 27-28 days/month. Even though the maximum daily values of sunshine do not show a strong intra-annual cycle, the highest values are observed in the months of July and August (their values reach 10 hours/day). The daily minimum sunshine does not exhibit null values and shows a maximum amount in the months of July and August of 1-2 hours per day. The annual cycle of the daily mean sunshine follows the intra-annual distribution of total sunshine, with peaks in July-August and December-January of 5 hours/day. In the periods of sunshine minima, the mean daily sunshine decreases to 4 hours/day. The standard deviation of daily sunshine behaves approximately steady all the year round, showing a mean value of 2.5 hours/day.

30

Figure 6.15. Annual cycles of total sunshine (SR1) and total foggy -null sunshine- days (SR2) observed in the spatial domain (04°25’N-05°15’N and 75°00’W-76°00’W). Error bars indicate the confidence interval for a 0.05 significance level.

Lt/Ln 76°00’

75°50’ 75°50’-75°40’ 75°40’-75°30’ 75°30’-75°20’

75°20’ 75°10’

75°10’-75°00’

05°10’ 05°15’

05°00’ 05°10’

(Station XV)

0

50

100

150

200

250

300

350

01 02 03 04 05 06 07 08 09 10 11 12

Month

Tota

l mon

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sun

shin

e [h

rs]

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25

30

Tota

l day

s nu

ll su

nshi

ne [n

umbe

r]

SR1 [hrs]

SR2 [days]

(Station 11)

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50

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150

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350

01 02 03 04 05 06 07 08 09 10 11 12

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Tota

l mon

thly

sun

shin

e [h

rs]

0

5

10

15

20

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30

Tota

l day

s nu

ll su

nshi

ne [n

umbe

r]

SR1 [hrs]

(Station II)

0

50

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150

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350

01 02 03 04 05 06 07 08 09 10 11 12

Month

Tota

l mon

thly

sun

shin

e [h

rs]

0

5

10

15

20

25

30

Tota

l day

s nu

ll su

nshi

ne [n

umbe

r]

SR1 [hrs ]

SR2 [days]

04°50’ 05°00’

(Station XII)*

0

50

100

150

200

250

300

350

01 02 03 04 05 06 07 08 09 10 11 12

Month

Tota

l mon

thly

sun

shin

e [h

rs]

0

5

10

15

20

25

30

Tota

l day

s nu

ll su

nshi

ne [n

umbe

r]

SR1 [hrs]

SR2 [days]

(Station I)

0

50

100

150

200

250

300

350

01 02 03 04 05 06 07 08 09 10 11 12

Month

Tota

l mon

thly

sun

shin

e [h

rs]

0

5

10

15

20

25

30

Tota

l day

s nu

ll su

nshi

ne [n

umbe

r]

SR1 [hrs ]

SR2 [days]

(Station XIX)

0

50

100

150

200

250

300

350

01 02 03 04 05 06 07 08 09 10 11 12

Month

Tota

l mon

thly

sun

shin

e [h

rs]

0

5

10

15

20

25

30

Tota

l day

s nu

ll su

nshi

ne [n

umbe

r]

SR1 [hrs ]

SR2 [days]

04°40’ 04°50’

(Station XVII)

0

50

100

150

200

250

300

350

01 02 03 04 05 06 07 08 09 10 11 12

Month

Tota

l mon

thly

sun

shin

e [h

rs]

0

5

10

15

20

25

30

Tota

l day

s nu

ll su

nshi

ne [n

umbe

r]

SR1 [hrs]

SR2 [days]

04°30’ 04°40’

04°25’ 04°30’

*The annual cycles of Station XII are representative of those observed at stations XIII, XVIII, and XX (their cycles are available in the memories). The annual cycles observed at Station XVI 2613507 El Cedral are presented in Figure 2.6.20.

31

Figure 6.16. Annual cycles of total sunshine (SR1) and total sunny days (TSD) observed in the spatial domain (04°25’N-05°15’N and 75°00’W-76°00’W). Error bars indicate the confidence interval for a 0.05 significance level.

Lt/Ln 76°00’

-75°50’

75°50’-75°40’ 75°40’-75°30’ 75°30’-75°20’ 75°20’

-75°10’

75°10’-75°00’

05°10’ 05°15’

05°00’ 05°10’

(Station XV)

0

50

100

150

200

250

300

350

01 02 03 04 05 06 07 08 09 10 11 12Month

Tot

al m

onth

ly s

unsh

ine

[hrs

]

0

5

10

15

20

25

30

Tota

l mon

thly

sun

ny d

ays

[num

ber]

SR1 [hrs]

TSD [days]

(Station II)

0

50

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350

01 02 03 04 05 06 07 08 09 10 11 12Month

Tota

l mon

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sun

shin

e [h

rs]

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5

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25

30

Tota

l mon

thly

sun

ny d

ays

[num

ber]

SR1 [hrs]

TSD [days]

04°50’ 05°00’

(Station XII)*

0

50

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01 02 03 04 05 06 07 08 09 10 11 12Month

Tota

l mon

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shin

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5

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20

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30

Tota

l mon

thly

sun

ny d

ays

[num

ber]

SR1 [hrs]

TSD [days]

(Station I)

0

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350

01 02 03 04 05 06 07 08 09 10 11 12Month

Tota

l mon

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sun

shin

e [h

rs]

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Tota

l mon

thly

sun

ny d

ays

[num

ber]

SR1 [hrs]

TSD [days]

(Station XIX)

0

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01 02 03 04 05 06 07 08 09 10 11 12Month

Tota

l mon

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sun

shin

e [h

rs]

0

5

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30

Tota

l mon

thly

sun

ny d

ays

[num

ber]

SR1 [hrs]

TSD [days]

04°40’ 04°50’

(Station XVII)

0

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250

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01 02 03 04 05 06 07 08 09 10 11 12Month

Tot

al m

onth

ly s

unsh

ine

[hrs

]

0

5

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20

25

30

Tota

l mon

thly

sun

ny d

ays

[num

ber]

SR1 [hrs]

TSD [days]

04°30’ 04°40’

04°25’-

04°30’

*The annual cycles of Station XII are representative of those observed at stations XIII and XVIII. The annual cycles observed at Station XVI 2613507 El Cedral are presented in Figure 2.6.20.

32

Figure 6.17. Annual cycles of daily maximum sunshine (SR4) and daily minimum sunshine (SR6) observed in the spatial domain (04°25’N-05°15’N and 75°00’W-76°00’W). Error bars indicate the confidence interval for a 0.05 significance level.

Lt/Ln 76°00’

-75°50’

75°50’-75°40’ 75°40’-75°30’ 75°30’-75°20’ 75°20’

-75°10’

75°10’-75°00’

05°10’ 05°15’

05°00’ 05°10’

(Station XV)

0

2

4

6

8

10

12

01 02 03 04 05 06 07 08 09 10 11 12

Month

Dai

ly m

axim

um s

unsh

ine

[hrs

]

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2

4

6

8

10

12

Dai

ly m

inim

um s

unsh

ine

[hrs

]

SR4 [hrs]

SR6 [hrs]

(Station II)

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01 02 03 04 05 06 07 08 09 10 11 12

Month

Dai

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mum

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rs]

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12

Dai

ly m

inim

um s

unsh

ine

[hrs

]

SR4 [hrs]

SR6 [hrs]

04°50’ 05°00’

(Station XII)*

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12

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Month

Dai

ly m

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ine

[hrs

]

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Dai

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unsh

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[hrs

]

SR4 [hrs]

SR6 [hrs]

(Station I)

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Dai

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ine

[hrs

]

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12

Dai

ly m

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unsh

ine

[hrs

]

SR4 [hrs]

SR6 [hrs]

(Station XIX)

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01 02 03 04 05 06 07 08 09 10 11 12

Month

Dai

ly m

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ine

[hrs

]

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10

12

Dai

ly m

inim

um s

unsh

ine

[hrs

]

SR4 [hrs ]

SR6 [hrs ]

04°40’ 04°50’

(Station XVII)

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01 02 03 04 05 06 07 08 09 10 11 12

Month

Dai

ly m

axim

um s

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ine

[hrs

]

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12

Dai

ly m

inim

um s

unsh

ine

[hrs

]

SR4 [hrs]

SR6 [hrs]

04°30’ 04°40’

04°25’-

04°30’


33

Figure 6.18. Annual cycles of daily mean sunshine (SR5) and standard deviation of daily sunshine (SR7) observed in the spatial domain (04°25’N-05°15’N and 75°00’W-76°00’W). Error bars indicate the confidence interval for a 0.05 significance level.

Lt/Ln 76°00’

-75°50’

75°50’-75°40’ 75°40’-75°30’ 75°30’-75°20’ 75°20’

-75°10’

75°10’-75°00’

05°10’ 05°15’

05°00’ 05°10’

(Station XV)

0

2

4

6

8

10

12

01 02 03 04 05 06 07 08 09 10 11 12Month

Dai

ly m

ean

sun

shin

e [h

rs]

0

2

4

6

8

10

12

SD

dai

ly s

unsh

ine

[hou

rs]

SR5 [hrs]

SR7 [hrs]

(Station II)

0

2

4

6

8

10

12

01 02 03 04 05 06 07 08 09 10 11 12Month

Dai

ly m

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(Station XII)*

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(Station XIX)

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(Station XVII)

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04°30’ 04°40’

04°25’-

04°30’


34

Analysis of the total sunshine in the weather station XVI El Cedral (see Figure 6.19) for the available period indicates that under ‘average’ conditions the sunshine patterns in the area also exhibit an intra-annual cycle with two peaks: the maximum total monthly sunshine during the trimester DJF is reached in the month of January and exhibits an average value of 90 hours; the maximum total monthly sunshine during the trimester JJA is observed in the months of July-August and reaches an average value of almost 115 hours. The total number of foggy days during the sunshine maxima reaches only 1-2 days/month (the total number of sunny days arrives to, consequently, 29-30 days/month); during sunshine minima, which are observed in the months of April, May, October, and November, the total number of foggy days increases to 3 days/month (TSD decreases to 28 days/month). The annual cycle of daily maximum sunshine exhibits a significant peak occurring in the months of July and August, with values of about 8 hours/day. The daily minimum sunshine of 0 hours/day is reached in the trimesters MAM and OND, and in the month of June. The daily mean sunshine in the area of the met station shows a minimum of 2 hours/day in the months of April and May, and a maximum value of almost 4 hours/day in the months of July and August. The standard deviation of daily sunshine also behaves approximately steady all the year round, showing a mean value of 1.8 hours/day with a slight increase of 0.2 hours/day in the months of July and August. At the met station Las Brisas the distribution of total sunshine is also bimodal, but maximum values of sunshine only reach 100 hours/month. The total monthly sunshine during periods of minima is of about 40-50 hours/month, more than half of what is observed at lower altitudes. The total number of foggy days during sunshine maxima reaches 3-4 days/month (the total number of sunny days show a consistent value of 26-27 days/month); the total number of foggy days during sunshine minima exhibits an extraordinary value of 8 days/month (the number of sunny days decreases, coherently, to 20-22 days/month). The daily maximum sunshine values exhibit a strong intra-annual cycle with maxima during the months of July and January (10 hours per day) and minimum values in the months of April and October (6 hours/day). Daily minimum sunshine values of 0 hours/day are observed all year round. The daily mean sunshine slightly fluctuates around 2.5 hours/day, with minimum and maximum values of about 1.9 and 3.5 hours per day, respectively. The standard deviation of daily sunshine follows the annual cycle of daily mean sunshine, with a mean of 2 hours/day. The sunshine patterns observed at lower levels on the eastern flank of the ACMR exhibit a similar distribution but with a very pronounced peak during the trimester July-August-September (JAS). In the trimester DJF, the maximum total amount of sunshine reaches almost 130-140 hours/month, whereas during the period JAS its value reaches 185 hours/month. The minimum total monthly sunshine is 100 days/month in the months of April and November. The total number of foggy days during sunshine maxima is, under average conditions, zero or less than 1 day/month (the total number of sunny days show a consistent value of 30 days/month); the total number of foggy days during sunshine minima reaches 2 days/month (sunny days decrease, coherently, to 28 days/month). Maximum sunshine values on the eastern flank of 11-12 hours/day are observed in the months of July and August; minimum null sunshine values are only reached in the trimester MAM. Finally, the annual cycle of daily mean sunshine also follows the intra-annual distribution of total sunshine, with a peak in the months of July and August of 6 hours/day; in the rest of the months, the mean sunshine is of about 4 hours per day. The standard deviation of daily sunshine also behaves approximately steady all the year round, showing a mean value of 2.5 hours/day.

35

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Figure 6.19. Annual cycles of sunshine observed at Station XVI 2613507 El Cedral. Top left: total monthly sunshine (SR1) and total foggy -null sunshine- days (SR2); top right: total monthly sunshine (SR1) and total sunny days (TSD); bottom left: daily maximum sunshine (SR4) and daily minimum sunshine (SR6); bottom right: daily mean sunshine (SR5) and standard deviation of daily sunshine (SR7). Error bars indicate the confidence interval for a 0.05 significance level. Data of rainfall: Figures 6.20 and 6.21 depict the annual cycles of total rainfall (R1), total dry days (R2), and maximum daily rainfall (R3) observed in the spatial domain. Minimum and maximum values on R1 bar plots are set to 0 and 600 mm/month; min and max values on R2 bar plots are set to 0 to 30 days/month; finally, min and max values on R3 bar plots are set to 0 to 100 mm/day. The latitudinal displacement of the InterTropical Convergence Zone (ITCZ) produces intra-annual cycles of rainfall with two peaks. They commonly occur during the trimesters Mar-April-May (MAM) and September-October-November (SON), and exhibit monthly values in the range 200-300 mm and 100-200 mm at lower and higher levels, respectively. Dry seasons are observed during the trimesters DJF and JJA; their rainfall amounts reach values in the range 100-200 mm and 50-100 mm at lower and higher levels, respectively. The total number of dry days (R2) also shows bi-modal annual cycles, but with peaks in the trimesters DJF and JJA. On the Western flank of the Central Mountain Range, R2 reaches values in the range from 15 to 20 days/month; on the Eastern flank, R2 reaches from 15 to 20 days/month at lower levels, and from 20 to 25 days/month at higher levels. During the wet seasons, R2 decreases to values in the range from 7 to 12 days/month. Finally, the annual cycles of maximum daily rainfall (R3) follow the intra-annual distributions of total sunshine. Average daily maximum rainfall events at lower altitudes reach from 50 to 60 mm during wet seasons, and from 30 to 40 mm during dry seasons. At higher altitudes, maximum daily rainfall events reach from 20 to 30 mm/day and from 10 to 20 mm/day, during wet and dry seasons, respectively.

36

Figure 6.20. Annual cycles of total rainfall (R1) and total dry days (R2) observed in the spatial domain (04°25’N-05°15’N and 75°00’W-76°00’W). Error bars indicate the confidence interval for a 0.05 significance level.

Lt/Ln 76°00’75°50’ 75°50’-75°40’ 75°40’-75°30’ 75°30’-75°20’ 75°20’ 75°10’ 75°10’-75°00’

05°10 05°15

(Station 7)

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04°50 05°00

(Station 1)*

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(Station XII)++

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(Station I)#

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(Station 5)

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(Station XIX)%

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04°40 04°50

(Station XVII)@

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(Station XXII)

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(Station XXIII)&

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04°30 04°40

(Station VII)

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(Station VIII)

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37

04°25 04°30

’

(Station IX)

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*The annual cycle of Station 1 is representative of that observed at Station 8. %The annual cycle of Station XIX is representative of that observed at Station 6. &The annual cycle of R1 at the weather Station 4 (Las Juntas) follows the one observed at the met Station XXIII, although its peaks in rainfall reach 200 mm in the months of May and September. ^The annual cycle of R1 observed at the Station XV is representative of that observed at Station 9. #The annual cycles of Station I are representative of those observed at stations X and XXVI, although peaks in rainfall during the months of April and October for the latter reach almost 300 and 250 mm, respectively. @The annual cycle of R1 at Station XVII is representative of that observed at Station VI. +The annual cycles of Station 11 are representative of those observed at weather stations 3, XXIV and XXV. ++The annual cycles of Station XII are representative of those observed at weather stations III, IV, V, XIII, XVI, XVIII, XX, and XXI. Figure 6.21. Annual cycles of total rainfall (R1) and maximum daily rainfall (R3) observed in the spatial domain (04°25’N-05°15’N and 75°00’W-76°00’W). Error bars indicate the confidence interval for a 0.05 significance level.

Lt/Ln 76°00’75°50’ 75°50’-75°40’ 75°40’-75°30’ 75°30’-75°20’ 75°20’ 75°10’ 75°10’-75°00’

05°10 05°15

(Station 7)

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(Station XII)++

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(Station XIX)

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38

04°40 04°50

(Station XVII)

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(Station VII)

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04°25 04°30

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(Station IX)

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#The annual cycles of Station I are representative of those observed at stations X and XXVI. +The annual cycles of Station 11 are representative of those observed at weather stations 3, XXIV and XXV. ++The annual cycles of Station XII are representative of those observed at weather stations III, IV, V, XIII, XVI, XVIII, XX, and XXI.

39

Data of minimum temperatures: Figures 6.22 and 6.23 depict the annual cycles of minimum temperatures observed on the warmest days (MTmin), minimum monthly temperatures (ATmin), and minimum temperatures observed on the coldest days (mTmin2) for the selected spatial domain. The annual cycles of the day-to-day standard deviation of minimum temperatures (SDTmin) are available in the back-up of these analyses. Minimum and maximum values of MTmin bar plots are set to 2 and 20°C; min and max values on ATmin plots are set to 0 and 22 °C; finally, min and max values on mTmin2 bar plots are set to –4 and 16°C. At lower levels on the Western flank of the ACMR minimum temperatures observed on the warmest days (MTmin) exhibit a uni-modal annual cycle with a peak occurring during the trimester MAM. The period of ‘low’ values usually occurs in the months of September and October. In the lowlands, along the Cauca River, the annual cycle is also uni-modal but the months of August and September tend to exhibit the lowest values of the year. At higher levels on the Western flank, minimum temperatures on the warmest days show a bi-modal annual cycle with peaks occurring during the months of April-May and October-November. Periods of low values are observed in the months of December-January and July-August. However, MTmin values do not vary significantly. On the Eastern flank, minimum temperatures observed on the warmest days at high altitudes also show a uni-modal annual cycle with maximum values in the months of April and May, and minimum records in the months of July through October. At lower altitudes, the intra-annual distribution seems to be bi-modal; peaks occur during the months of April-May and October-November, whereas low values are particularly observed in the months of July and August. Minimum temperatures observed under ‘average’ conditions (ATmin) and minimum temperatures observed on the coldest days (mTmin2) follow the intra-annual distributions discussed for MTmin at all altitudes and in both flanks. Data of maximum temperatures: Figures 6.24 and 6.25 depict the annual cycles of maximum temperatures observed on the warmest days (MTmax), maximum monthly temperatures (ATmax), and maximum temperatures observed on the coldest days (mTmax2) for the selected spatial domain. The annual cycles of the day-to-day standard deviation of maximum temperatures (SDTmax) are available in the back-up of these analyses. Minimum and maximum values of MTmax, ATmax, and mTmax2 bar plots are all set to 5 and 30°C, respectively. At lower levels on the Western flank of the ACMR maximum temperatures observed on the warmest days (MTmax) exhibit a bi-modal annual cycle that seems to decrease toward the end of the year. Peaks commonly occur during the months of February-March and July-August, whereas periods of ‘low’ values usually take place in the months of May-June and October-November. The months of February-March are the warmest of the year; the months of October-November tend to show the lowest MTmax values. In the lowlands, along the Cauca River, the annual cycle is also bi-modal but the months of July and August are the warmest of the year. At higher levels on the Western flank, maximum temperatures on the warmest days do not exhibit such marked annual cycle (MTmax tend not to vary throughout the year). On the Eastern flank, maximum temperatures observed on the warmest days at high altitudes show a uni-modal annual cycle with maximum values in the months of April through June, and minimum records in the months of December and January. At lower altitudes, the intra-annual distribution is bi-modal; the months of August and September are, however, the warmest of the year. Maximum temperatures observed under ‘average’ conditions (ATmax) and maximum temperatures observed on the coldest days (mTmax2) follow the intra-annual distributions discussed for MTmax at all altitudes and in both flanks.

40

Figure 6.22. Annual cycles of minimum temperatures observed on the warmest days (MTmin) and under ‘average’ conditions (ATmin) for the spatial domain (04°25’N-05°15’N and 75°00’W-76°00’W). Error bars indicate the confidence interval for a 0.05 significance level.

Lt/Ln 76°00’75°50’ 75°50’-75°40’ 75°40’-75°30’ 75°30’-75°20’ 75°20’ 75°10’ 75°10’-75°00’ 05°10’ 05°15’

05°00’ 05°10’

(Station XV)

2

4

6

8

10

12

14

16

18

20

01 02 03 04 05 06 07 08 09 10 11 12

Month

Min

imum

mon

thly

tem

pera

ture

s [°C

] (w

arm

est d

ays)

0

5

10

15

20

Min

imum

mon

thly

tem

pera

ture

s [°C

]

MTmin [C]

ATmin [C]

(Station II)

2

4

6

8

10

12

14

16

18

20

01 02 03 04 05 06 07 08 09 10 11 12

Month

Min

imum

mon

thly

tem

pera

ture

s [°C

] (w

arm

est d

ays)

0

5

10

15

20

Min

imum

mon

thly

tem

pera

ture

s [°C

]

MTmin [C]

ATmin [C]

04°50’ 05°00’

(Station XII)@

2

4

6

8

10

12

14

16

18

20

01 02 03 04 05 06 07 08 09 10 11 12

Month

Min

imum

mon

thly

tem

pera

ture

s [°C

] (w

arm

est d

ays)

0

5

10

15

20

Min

imum

mon

thly

tem

pera

ture

s [°C

]

MTmin [C]

ATmin [C]

(Station I)

2

4

6

8

10

12

14

16

18

20

01 02 03 04 05 06 07 08 09 10 11 12

Month

Min

imum

mon

thly

tem

pera

ture

s [°C

] (w

arm

est d

ays)

0

5

10

15

20

Min

imum

mon

thly

tem

pera

ture

s [°C

]

MTmin [C]

ATmin [C]

(Station XIX)

2

4

6

8

10

12

14

16

18

20

01 02 03 04 05 06 07 08 09 10 11 12

Month

Min

imum

mon

thly

tem

pera

ture

s [°C

] (w

arm

est d

ays)

0

5

10

15

20

Min

imum

mon

thly

tem

pera

ture

s [°C

]

MTmin [C]

ATmin [C]

04°40’ 04°50’

(Station XVII)

2

4

6

8

10

12

14

16

18

20

01 02 03 04 05 06 07 08 09 10 11 12

Month

Min

imum

mon

thly

tem

pera

ture

s [°C

] (w

arm

est d

ays)

0

5

10

15

20

Min

imum

mon

thly

tem

pera

ture

s [°C

]

MTmin [C]

ATmin [C]

04°30’ 04°40’

(Station VII)

2

4

6

8

10

12

14

16

18

20

01 02 03 04 05 06 07 08 09 10 11 12

Month

Min

imum

mon

thly

tem

pera

ture

s [°C

] (w

arm

est d

ays)

0

5

10

15

20

Min

imum

mon

thly

tem

pera

ture

s [°C

]

MTmin [C]

ATmin [C]

04°25’ 04°30’

@The annual cycles of Station XII are representative of those observed at weather stations XIII, XVI, and XVIII.

41

Figure 6.23. Annual cycles of minimum temperatures observed on the coldest days (mTmin2) and minimum monthly temperatures (ATmin) observed in the spatial domain (04°25’N-05°15’N and 75°00’W-76°00’W). Error bars indicate the confidence interval for a 0.05 significance level.

Lt/Ln 76°00’75°50’ 75°50’-75°40’ 75°40’-75°30’ 75°30’-75°20’ 75°20’ 75°10’ 75°10’-75°00’ 05°10’ 05°15’

05°00’ 05°10’

(Station XV)

-4

-2

0

2

4

6

8

10

12

14

16

01 02 03 04 05 06 07 08 09 10 11 12Month

Min

imum

mon

thly

tem

pera

ture

s [°C

] (c

olde

st d

ays)

0

5

10

15

20

Min

imum

mon

thly

tem

pera

ture

s [°C

]

mTmin2 [C]

ATmin [C]

(Station 11)

-4

-2

0

2

4

6

8

10

12

14

16

01 02 03 04 05 06 07 08 09 10 11 12Month

Min

imum

mon

thly

tem

pera

ture

s [°C

] (c

olde

st d

ays)

-5

0

5

10

15

20

Min

imum

mon

thly

tem

pera

ture

s [°C

]

mTmin2 [C]

ATmin [C]

(Station II)

-4

-2

0

2

4

6

8

10

12

14

16

01 02 03 04 05 06 07 08 09 10 11 12Month

Min

imum

mon

thly

tem

pera

ture

s [°C

] (c

olde

st d

ays)

0

5

10

15

20

Min

imum

mon

thly

tem

pera

ture

s [°C

]

mTmin2 [C]

ATmin [C]

04°50’ 05°00’

(Station XII)%

-4

-2

0

2

4

6

8

10

12

14

16

01 02 03 04 05 06 07 08 09 10 11 12Month

Min

imum

mon

thly

tem

pera

ture

s [°C

] (c

olde

st d

ays)

0

5

10

15

20

Min

imum

mon

thly

tem

pera

ture

s [°C

]

mTmin2 [C]

ATmin [C]

(Station I)

-4

-2

0

2

4

6

8

10

12

14

16

01 02 03 04 05 06 07 08 09 10 11 12Month

Min

imum

mon

thly

tem

pera

ture

s [°C

] (c

olde

st d

ays)

0

5

10

15

20

Min

imum

mon

thly

tem

pera

ture

s [°C

]

mTmin2 [C]

ATmin [C]

(Station XIX)

-4

-2

0

2

4

6

8

10

12

14

16

01 02 03 04 05 06 07 08 09 10 11 12Month

Min

imum

mon

thly

tem

pera

ture

s [°C

] (c

olde

st d

ays)

0

5

10

15

20

Min

imum

mon

thly

tem

pera

ture

s [°C

]

mTmin2 [C]

ATmin [C]

04°40’ 04°50’

(Station XVII)@

-4

-2

0

2

4

6

8

10

12

14

16

01 02 03 04 05 06 07 08 09 10 11 12Month

Min

imum

mon

thly

tem

pera

ture

s [°C

] (c

olde

st d

ays)

0

5

10

15

20

Min

imum

mon

thly

tem

pera

ture

s [°C

]

mTmin2 [C]

ATmin [C]

(Station XXII)

-4

-2

0

2

4

6

8

10

12

14

16

01 02 03 04 05 06 07 08 09 10 11 12Month

Min

imum

mon

thly

tem

pera

ture

s [°C

] (c

olde

st d

ays)

-5

0

5

10

15

20

Min

imum

mon

thly

tem

pera

ture

s [°C

]

mTmin2 [C]

ATmin [C]

04°30’ 04°40’

(Station VII)

-4

-2

0

2

4

6

8

10

12

14

16

01 02 03 04 05 06 07 08 09 10 11 12Month

Min

imum

mon

thly

tem

pera

ture

s [°C

] (c

olde

st d

ays)

0

5

10

15

20

Min

imum

mon

thly

tem

pera

ture

s [°C

]

mTmin2 [C]

ATmin [C]

04°25’ 04°30’

@The annual cycles of Station XVII are representative of those observed at the weather station VI. %The annual cycles of Station XII are representative of those observed at weather stations XIII, XVI, XVIII, XX, and XXI.

42

Figure 6.24. Annual cycles of maximum temperatures observed on the warmest days (MTmax) and under ‘average’ conditions (ATmax) for the spatial domain (04°25’N-05°15’N and 75°00’W-76°00’W). Error bars indicate the confidence interval for a 0.05 significance level.

Lt/Ln 76°00’75°50’ 75°50’-75°40’ 75°40’-75°30’ 75°30’-75°20’ 75°20’ 75°10’ 75°10’-75°00’ 05°10’ 05°15’

05°00’ 05°10’

(Station XV)

5

10

15

20

25

30

01 02 03 04 05 06 07 08 09 10 11 12

Month

Max

imum

mon

thly

tem

pera

ture

s [°C

] (w

arm

est d

ays)

5

10

15

20

25

30

Max

imum

mon

thly

tem

pera

ture

s [°C

]

MTmax [C]

ATmax [C]

(Station 11)

5

10

15

20

25

30

01 02 03 04 05 06 07 08 09 10 11 12

Month

Max

imum

mon

thly

tem

pera

ture

s [°C

] (w

arm

est d

ays)

5

10

15

20

25

30

Max

imum

mon

thly

tem

pera

ture

s [°C

]

MTmax [C]

ATmax [C]

(Station II)

5

10

15

20

25

30

01 02 03 04 05 06 07 08 09 10 11 12

Month

Max

imum

mon

thly

tem

pera

ture

s [°C

] (w

arm

est d

ays)

5

10

15

20

25

30

Max

imum

mon

thly

tem

pera

ture

s [°C

]

MTmax [C]

ATmax [C]

04°50’ 05°00’

(Station XII)@

5

10

15

20

25

30

01 02 03 04 05 06 07 08 09 10 11 12

Month

Max

imum

mon

thly

tem

pera

ture

s [°C

] (w

arm

est d

ays)

5

10

15

20

25

30

Max

imum

mon

thly

tem

pera

ture

s [°C

]

MTmax [C]

ATmax [C]

(Station I)

5

10

15

20

25

30

01 02 03 04 05 06 07 08 09 10 11 12

Month

Max

imum

mon

thly

tem

pera

ture

s [°C

] (w

arm

est d

ays)

5

10

15

20

25

30

Max

imum

mon

thly

tem

pera

ture

s [°C

]

MTmax [C]

ATmax [C]

(Station XIX)

5

10

15

20

25

30

01 02 03 04 05 06 07 08 09 10 11 12

Month

Max

imum

mon

thly

tem

pera

ture

s [°C

] (w

arm

est d

ays)

5

10

15

20

25

30

Max

imum

mon

thly

tem

pera

ture

s [°C

]

MTmax [C]

ATmax [C]

04°40’ 04°50’

(Station XVII)

5

10

15

20

25

30

01 02 03 04 05 06 07 08 09 10 11 12

Month

Max

imum

mon

thly

tem

pera

ture

s [°C

] (w

arm

est d

ays)

5

10

15

20

25

30

Max

imum

mon

thly

tem

pera

ture

s [°C

]

MTmax [C]

ATmax [C]

04°30’ 04°40’

(Station VII)

5

10

15

20

25

30

01 02 03 04 05 06 07 08 09 10 11 12

Month

Max

imum

mon

thly

tem

pera

ture

s [°C

] (w

arm

est d

ays)

5

10

15

20

25

30

Max

imum

mon

thly

tem

pera

ture

s [°C

]

MTmax [C]

ATmax [C]

04°25’ 04°30’

@The annual cycles of Station XII are representative of those observed at weather stations XIII, XVI, XVIII, XX, and XXI.

43

Figure 6.25. Annual cycles of maximum temperatures observed on the coldest days (mTmax2) and maximum monthly temperatures (ATmax) observed in the spatial domain (04°25’N-05°15’N and 75°00’W-76°00’W). Error bars indicate the confidence interval for a 0.05 significance level.

Lt/Ln 76°00’75°50’ 75°50’-75°40’ 75°40’-75°30’ 75°30’-75°20’ 75°20’ 75°10’ 75°10’-75°00’ 05°10’ 05°15’

05°00’ 05°10’

(Station XV)

5

10

15

20

25

30

01 02 03 04 05 06 07 08 09 10 11 12Month

Max

imum

mon

thly

tem

pera

ture

s [°C

] (c

olde

st d

ays)

5

10

15

20

25

30

Max

imum

mon

thly

tem

pera

ture

s [°C

]

mTmax2 [C]

ATmax [C]

(Station II)

5

10

15

20

25

30

01 02 03 04 05 06 07 08 09 10 11 12Month

Max

imum

mon

thly

tem

pera

ture

s [°C

] (c

olde

st d

ays)

5

10

15

20

25

30

Max

imum

mon

thly

tem

pera

ture

s [°C

]

mTmax2 [C]

ATmax [C]

04°50’ 05°00’

(Station XII)%

5

10

15

20

25

30

01 02 03 04 05 06 07 08 09 10 11 12Month

Max

imum

mon

thly

tem

pera

ture

s [°C

] (c

olde

st d

ays)

5

10

15

20

25

30

Max

imum

mon

thly

tem

pera

ture

s [°C

]

mTmax2 [C]

ATmax [C]

(Station I)

5

10

15

20

25

30

01 02 03 04 05 06 07 08 09 10 11 12Month

Max

imum

mon

thly

tem

pera

ture

s [°C

] (c

olde

st d

ays)

5

10

15

20

25

30

Max

imum

mon

thly

tem

pera

ture

s [°C

]

mTmax2 [C]

ATmax [C]

(Station XIX)

5

10

15

20

25

30

01 02 03 04 05 06 07 08 09 10 11 12Month

Max

imum

mon

thly

tem

pera

ture

s [°C

] (c

olde

st d

ays)

5

10

15

20

25

30

Max

imum

mon

thly

tem

pera

ture

s [°C

]

mTmax2 [C]

ATmax [C]

04°40’ 04°50’

(Station XVII)

5

10

15

20

25

30

01 02 03 04 05 06 07 08 09 10 11 12Month

Max

imum

mon

thly

tem

pera

ture

s [°C

] (c

olde

st d

ays)

5

10

15

20

25

30

Max

imum

mon

thly

tem

pera

ture

s [°C

]

mTmax2 [C]

ATmax [C]

04°30’ 04°40’

(Station VII)

5

10

15

20

25

30

01 02 03 04 05 06 07 08 09 10 11 12Month

Max

imum

mon

thly

tem

pera

ture

s [°C

] (c

olde

st d

ays)

5

10

15

20

25

30

Max

imum

mon

thly

tem

pera

ture

s [°C

]

mTmax2 [C]

ATmax [C]

04°25’ 04°30’

%The annual cycles of Station XII are representative of those observed at weather stations XIII, XVI, and XVIII.

44

Data of relative humidity: Figures 6.26 and 6.27 depict the annual cycles of maximum (MRH), mean (ARH), and minimum (mRH2) relative humidity values observed in the selected spatial domain. The annual cycles of the day-to-day standard deviation of relative humidity (SDRH) are available in the back-up of these analyses. Minimum and maximum values of MRH, ARH, and mRH2 bar plots are all set to 50 and 100%, respectively. Weather stations located at lower levels exhibit maximum relative humidity values (MRH) with bi-modal annual cycles. Peaks tend to occur during the trimesters April-May-June and SON. Periods of ‘low’ relative humidity values are commonly observed during the months of January-February and July-August. At higher levels, MRH values are almost constant all year round. Analysis of mean monthly relative humidity values (ARH) indicates that under ‘average’ conditions lower altitudes experience bi-modal intra-annual cycles with similar timing. The bi-modal distribution is also exhibited by the records at higher levels. It is worth to mention, however, that mean relative humidity values over the Eastern flank of the ACMR seem to be strongly reduced during the months of July and August. According to the analyses of annual cycles of minimum relative humidity values (mRH2), lower altitude areas experience a critical period of ‘dry’ conditions during the months of July and August. Reductions in relative humidity are stronger in those weather stations located at lower altitudes along the Cauca and Magdalena rivers. At higher altitudes, this reduction in humidity is not very pronounced. Data of diurnal temperature range: Figures 6.28 and 6.29 depict the annual cycles of maximum (MDTR), mean (ADTR), and minimum (mDTR2) diurnal temperature range observed in the selected spatial domain. The annual cycles of the day-to-day standard deviation of diurnal temperature range (SDDTR) are available in the back-up of these analyses. Minimum and maximum values of MDTR bar plots are set to 5 and 17 °C, respectively; minimum and maximum values of ADTR are defined to be 5 and 13 °C, respectively; finally, mDTR2 values are plotted for the range [0; 10°C]. Maximum, mean, and minimum diurnal temperature range values exhibit bi-modal annual cycles with peaks occurring during the months of July-August-September (JAS) and December-January-February-March. Periods of low diurnal temperature range are commonly observed during the months of October-November and April-May. Under ‘average’ conditions these peaks and periods of low tend to show similar orders of magnitude on the Western flank of the ACMR. Over the Eastern flank, on the contrary, the peak occurring in the trimester JAS shows the highest values. Data of potential evaporation: Figure 6.30 depicts the annual cycles of potential evaporation (EVP) observed in four weather stations located in the surroundings of the Los Nevados Natural Park (stations 11, VI, XX, and XXII, all of them on the Western flank of the ACMR). Minimum and maximum values of EVP bar plots are set to 0 and 150 mm/month, respectively. Under ‘average’ conditions peaks in EVP occur during the months of DJF and July-August-September. Periods of low are observed during the months of April-May-June and October-November. Data of dew point: left panel of Figure 6.31 depicts the annual cycle of dew point (Td) observed at the met station VI Apto Matecana. Records exhibit a bi-modal annual cycle with peaks occurring during the months of April-May-June and October-November-December. Periods of low Td are commonly observed during the months of January-February and August-September. Data of vapor pressure: left panel of Figure 6.31 also depicts the annual cycle of vapor pressure (e) observed at the met station VI Apto Matecana. As expected, records follow the intra-annual cycle of dew point discussed above.

45

Figure 6.26. Annual cycles of maximum (MRH) and mean (ARH) relative humidity values observed in the spatial domain (04°25’N-05°15’N and 75°00’W-76°00’W). Error bars indicate the confidence interval for a 0.05 significance level.

Lt/Ln 76°00’75°50’ 75°50’-75°40’ 75°40’-75°30’ 75°30’-75°20’ 75°20’ 75°10’ 75°10’-75°00’ 05°10’ 05°15’

05°00’ 05°10’

(Station XV)

50

55

60

65

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75

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85

90

95

100

01 02 03 04 05 06 07 08 09 10 11 12

Month

Max

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mon

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rel

ativ

e hu

mid

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[%]

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85

90

95

100

Mea

n m

onth

ly r

elat

ive

hum

idity

[%]

MRH [%]

ARH [%]

(Station 11)

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65

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85

90

95

100

01 02 03 04 05 06 07 08 09 10 11 12

Month

Max

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mon

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mid

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[%]

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85

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100

Mea

n m

onth

ly r

elat

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hum

idity

[%]

MRH [%]

ARH [%]

(Station II)

50

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100

01 02 03 04 05 06 07 08 09 10 11 12

Month

Max

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[%]

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Mea

n m

onth

ly r

elat

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hum

idity

[%]

MRH [%]

ARH [%]

04°50’ 05°00’

(Station XII)@

50

55

60

65

70

75

80

85

90

95

100

01 02 03 04 05 06 07 08 09 10 11 12

Month

Max

imum

mon

thly

rel

ativ

e hu

mid

ity

[%]

50

55

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85

90

95

100

Mea

n m

onth

ly r

elat

ive

hum

idity

[%]

MRH [%]

ARH [%]

(Station I)

50

55

60

65

70

75

80

85

90

95

100

01 02 03 04 05 06 07 08 09 10 11 12

Month

Max

imum

mon

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e hu

mid

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[%]

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95

100

Mea

n m

onth

ly r

elat

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hum

idity

[%]

MRH [%]

ARH [%]

(Station XIX)

50

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85

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95

100

01 02 03 04 05 06 07 08 09 10 11 12

Month

Max

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mon

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mid

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[%]

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100

Mea

n m

onth

ly r

elat

ive

hum

idity

[%]

MRH [%]

ARH [%]

04°40’ 04°50’

(Station XVII)&

50

55

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65

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75

80

85

90

95

100

01 02 03 04 05 06 07 08 09 10 11 12

Month

Max

imum

mon

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mid

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[%]

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100

Mea

n m

onth

ly r

elat

ive

hum

idity

[%]

MRH [%]

ARH [%]

04°30’ 04°40’

04°25’ 04°30’

@The annual cycles of Station XII are representative of those observed at weather stations XIII, XVI, XVIII, XX, and XXI. &The annual cycles of Station XVII are representative of those observed at the weather station VI.

46

Figure 6.27. Annual cycles of minimum (mRH2) and mean (ARH) relative humidity values observed in the spatial domain (04°25’N-05°15’N and 75°00’W-76°00’W). Error bars indicate the confidence interval for a 0.05 significance level.

Lt/Ln 76°00’75°50’ 75°50’-75°40’ 75°40’-75°30’ 75°30’-75°20’ 75°20’ 75°10’ 75°10’-75°00’ 05°10’ 05°15’

05°00’ 05°10’

(Station XV)

50

55

60

65

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75

80

85

90

95

100

01 02 03 04 05 06 07 08 09 10 11 12Month

Min

imum

mon

thly

rel

ativ

e hu

mid

ity[%

]

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75

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85

90

95

100

Mea

n m

onth

ly r

elat

ive

hum

idity

[%]

mRH2 [%]

ARH [%]

(Station 11)

50

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65

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75

80

85

90

95

100

01 02 03 04 05 06 07 08 09 10 11 12Month

Min

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mon

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mid

ity[%

]

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95

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Mea

n m

onth

ly r

elat

ive

hum

idity

[%]

mRH2 [%]

ARH [%]

(Station II)

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65

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75

80

85

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95

100

01 02 03 04 05 06 07 08 09 10 11 12Month

Min

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mid

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]

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Mea

n m

onth

ly r

elat

ive

hum

idity

[%]

mRH2 [%]

ARH [%]

04°50’ 05°00’

(Station XII)%

50

55

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65

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75

80

85

90

95

100

01 02 03 04 05 06 07 08 09 10 11 12Month

Min

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mon

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mid

ity[%

]

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85

90

95

100

Mea

n m

onth

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elat

ive

hum

idity

[%]

mRH2 [%]

ARH [%]

(Station I)

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100

01 02 03 04 05 06 07 08 09 10 11 12Month

Min

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]

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95

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Mea

n m

onth

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idity

[%]

mRH2 [%]

ARH [%]

(Station XIX)

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01 02 03 04 05 06 07 08 09 10 11 12Month

Min

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]

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Mea

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idity

[%]

mRH2 [%]

ARH [%]

04°40’ 04°50’

(Station XVII)&

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01 02 03 04 05 06 07 08 09 10 11 12Month

Min

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]

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Mea

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onth

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idity

[%]

mRH2 [%]

ARH [%]

04°30’ 04°40’

04°25’ 04°30’

%The annual cycles of Station XII are representative of those observed at weather stations XIII, XVI, and XVIII. &The annual cycles of Station XVII are representative of those observed at the weather station VI.

47

Figure 6.28. Annual cycles of maximum (MDTR) and mean (ADTR) diurnal temperature range values observed in the spatial domain (04°25’N-05°15’N and 75°00’W-76°00’W). Error bars indicate the confidence interval for a 0.05 significance level.

Lt/Ln 76°00’75°50’ 75°50’-75°40’ 75°40’-75°30’ 75°30’-75°20’ 75°20’ 75°10’ 75°10’-75°00’ 05°10’ 05°15’

05°00’ 05°10’

(Station XV)

5

7

9

11

13

15

17

01 02 03 04 05 06 07 08 09 10 11 12

Month

Max

imum

mon

thly

DTR

[°C

]

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6

7

8

9

10

11

12

13

Mea

n m

onth

ly D

TR [°

C]

MDTR [C]

ADTR [C]

(Station II)

5

7

9

11

13

15

17

01 02 03 04 05 06 07 08 09 10 11 12

Month

Max

imum

mon

thly

DTR

[°C

]

5

6

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8

9

10

11

12

13

Mea

n m

onth

ly D

TR [°

C]

MDTR [C]

ADTR [C]

04°50’ 05°00’

(Station XII)@

5

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9

11

13

15

17

01 02 03 04 05 06 07 08 09 10 11 12

Month

Max

imum

mon

thly

DTR

[°C

]

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Mea

n m

onth

ly D

TR [°

C]

MDTR [C]

ADTR [C]

(Station I)

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17

01 02 03 04 05 06 07 08 09 10 11 12

Month

Max

imum

mon

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DTR

[°C

]

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9

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n m

onth

ly D

TR [°

C]

MDTR [C]

ADTR [C]

(Station XIX)

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17

01 02 03 04 05 06 07 08 09 10 11 12

Month

Max

imum

mon

thly

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[°C

]

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Mea

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onth

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TR [°

C]

MDTR [C]

ADTR [C]

04°40’ 04°50’

(Station XVII)

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Month

Max

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mon

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[°C

]

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n m

onth

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TR [°

C]

MDTR [C]

ADTR [C]

04°30’ 04°40’

(Station VII)

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Month

Max

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[°C

]

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12

13

Mea

n m

onth

ly D

TR [°

C]

MDTR [C]

ADTR [C]

04°25’ 04°30’


48

Figure 6.29. Annual cycles of minimum (mDTR2) and mean (ADTR) diurnal temperature range values observed in the spatial domain (04°25’N-05°15’N and 75°00’W-76°00’W). Error bars indicate the confidence interval for a 0.05 significance level.

Lt/Ln 76°00’75°50’ 75°50’-75°40’ 75°40’-75°30’ 75°30’-75°20’ 75°20’ 75°10’ 75°10’-75°00’ 05°10’ 05°15’

05°00’ 05°10’

(Station XV)

0

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10

01 02 03 04 05 06 07 08 09 10 11 12Month

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[°C

]

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9

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12

13

Mea

n m

onth

ly D

TR [°

C]

mDTR [C]

ADTR [C]

(Station II)

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10

01 02 03 04 05 06 07 08 09 10 11 12Month

Min

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[°C

]

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9

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11

12

13

Mea

n m

onth

ly D

TR [°

C]

mDTR [C]

ADTR [C]

04°50’ 05°00’

(Station XII)@

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Min

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[°C

]

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9

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11

12

13

Mea

n m

onth

ly D

TR [°

C]

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ADTR [C]

(Station I)

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01 02 03 04 05 06 07 08 09 10 11 12Month

Min

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[°C

]

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Mea

n m

onth

ly D

TR [°

C]

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ADTR [C]

(Station XIX)

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Min

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[°C

]

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12

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Mea

n m

onth

ly D

TR [°

C]

mDTR [C]

ADTR [C]

04°40’ 04°50’

(Station XVII)

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]

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Mea

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onth

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TR [°

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04°30’ 04°40’

(Station VII)

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Mea

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onth

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TR [°

C]

mDTR [C]

ADTR [C]

04°25’ 04°30’


49

Data of cloud cover (observed from the ground): right panel of Figure 6.31 depicts the annual cycle of cloud cover observed from the ground at the weather station 11 Apto La Nubia. Periods of high amounts are observed in the months of April-May-June and SON; reductions in cloud cover are commonly observed in the months of DJF and July-August. Data of wind speed/direction: right panel of Figure 6.31 also depicts the annual cycle of wind speed observed at the weather station 11 Apto La Nubia. Although data are limited for conducting the analyses, it can be mentioned that increases in wind speed commonly occur during the months of December-January and July-August. Data of wind direction are very limited for the analyses of intra-annual conditions.

0

20

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100

120

140

01 02 03 04 05 06 07 08 09 10 11 12

Month

Tot

al p

oten

tial e

vapo

ratio

n [m

m]

0

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40

60

80

100

120

140

Tot

al p

oten

tial e

vapo

ratio

n [m

m]

(11) 2615511 (VI) 2613504

995.5 + 185.1 mm/year

1,386.1 + 85.5 mm/year

0

20

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140

01 02 03 04 05 06 07 08 09 10 11 12Month

Tot

al p

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vapo

ratio

n [m

m]

0

20

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100

120

140

Tot

al p

oten

tial e

vapo

ratio

n [m

m]

(XX) 2613511 (XXII) 2613514

882.1 + 83.3mm/year

705.9 + 86.9mm/year

Figure 6.30. Annual cycles of potential evaporation observed in the spatial domain (04°25’N-05°15’N and 75°00’W-76°00’W). See also total annual EVP. Left panel: stations 11 Apto La Nubia and VI Apto Matecana; right panel: stations XX Veracruz and XXII La Laguna. Error bars indicate the confidence interval for a 0.05 significance level.

15,8

16,0

16,2

16,4

16,6

16,8

17,0

17,2

17,4

17,6

17,8

01 02 03 04 05 06 07 08 09 10 11 12

Month

Mea

n m

onth

ly d

ew p

oint

[C]

18,0

18,5

19,0

19,5

20,0

20,5

Mea

n m

onth

ly v

apor

pre

ssur

e [1

0^2*

kg/m

/s^2

]

Td e

Mean annual Td :17.0 + 0.5

Mean annual e :19.4 + 0.6

0

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8

01 02 03 04 05 06 07 08 09 10 11 12

Month

Mea

n m

onth

ly c

loud

cov

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ctan

ts]

0,0

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4,5

Mea

n m

onth

ly w

ind

spee

d [m

/s]

CC v

Figure 6.31. Annual cycles of dew point (Td) and vapor pressure (e) observed at the weather station VI Apto Matecana (left panel). Annual cycles of cloud cover (observed from the ground) and wind speed observed at the weather station 11 Apto La Nubia (right panel). Error bars indicate the confidence interval for a 0.05 significance level.

50

6.3.3. Long-term trend Figure 6.32 depicts the first two Empirical Orthogonal Function modes of January SST anomalies observed in the 30°S-30°N and 15°S-15°N Indo-Pacific tropical regions over the period 1942-2007. Table 6.12 shows the percentages of the spatio-temporal variability of SST anomalies explained by the first and second modes for all the analyzed regions. Figure 6.33 depicts the first two Principal Components of January, February, July, and August SST anomalies observed in the same spatial domain. The first principal component of January SST anomalies observed in the 30°S-to-30°N Indo-Pacific region exhibits, in particular, a statistically significant decreasing trend over the period 1951-2007. The trend seems to encompass the slow warming over time of ocean temperatures due to the effects of global warming. The slope of the linear trend and the explained variance of January PC1 reach –0.1756 and 15.3%, respectively. PC1 values clearly exceed the +1.0 standard deviation envelopes during the strong La Nina (1955-56, 1973-74, 1975-76, and 1988-89) and El Nino (1972-73, 1982-83, and 1997-98) events. Further, six La Nina events and only three El Nino events occurred before 1976, whereas only three La Nina events and eight El Nino events have happened after 1976 (the first PC of January SSTa exhibits increasing –positive slope of about 0.1643– and decreasing trends –negative slope of about 0.0405– over the periods 1951-1976 and 1977-2007, respectively).

Figure 6.32. Empirical Orthogonal Function modes of January SST anomalies observed in the Indo-Pacific region. First loading patterns for the regions extending from 30°S to 30°N (top left panel) and 15°S to 15°N (top right panel); second loading patterns for the regions extending from 30°S to 30°N (bottom left panel) and 15°S to 15°N (bottom right panel). The first EOF modes suggest a pool of relatively ‘cold’ waters in the Eastern Pacific and a band of slightly warmer water in the Indonesia area.

Table 6.12. Percentage of the variance of SST anomalies explained by EOF modes

Month Region First EOF mode Second EOF mode January

30°S to 30°N Indo-Pacific

30.7 13.7 February 28.9 13.4 July 22.7 13.3 August 24.3 14.6 January

Tropical Atlantic

32.0 23.6 February 34.8 25.4 July 40.6 16.0 August 42.8 16.0 January

15°S to 15°N Indo-Pacific

44.3 15.6 February 41.1 14.4 July 31.0 17.5 August 32.8 18.9

51

-20

-15

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-5

0

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201

94

2

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20

02

Year

PC

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94

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19

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19

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20

02

PC

1

Jan Feb

Jul Aug-20

-15

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-5

0

5

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Year

PC

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PC

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Jul Aug

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Jul Aug-20

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PC

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Jan Feb

Jul Aug

Figure 6.33. Principal components of SST anomalies observed in the Indo-Pacific region. Months of January, February, July, and August are represented, respectively, by the gray solid line, the gray pluses, the red solid line, and the red pluses. The first principal components (PC1) for the regions extending from 30°S to 30°N and 15°S to 15°N are presented in the top left and top right panels, respectively; the second principal components (PC2) for the regions extending from 30°S to 30°N and 15°S to 15°N are presented in the bottom left and bottom right panels, respectively. Data of cloud characteristics: the ‘long-term’ mean value of optical depth over the selected grid point reaches 7.5. Minimum and maximum values reach 3.7 and 14.0, respectively. A significant trend in the mean is not observed in the historical time series over the recorded period. The cloud amount exhibits ‘long-term’ mean, minimum and maximum values of about 80.6, 47.0 and 88.5, respectively. A decrease in all-type cloud cover of about 1.9%/decade is observed over the period 1983-2001. The top pressure for multiple clouds exhibits a mean annual value of about 439 mb. Minimum and maximum observed values reach, respectively, 355 and 570 mb. Satellite records suggest a decrease in mean annual top pressure for multiple clouds from 450 mb in the early 80s to almost 425 mb in 2001. Finally, top temperatures for all-type clouds exhibit mean, minimum and maximum values of about 256.2, 246.1 and 269.1 K, respectively. A decreasing trend, but not significant, is observed in the historical records of top temperatures over the period 1983-2001. Correlation coefficients between all-type cloud amounts observed over the period from July, 1983 to August, 2001 and the Nino 3.4 SST for time lags of 0, 1, and 2 months reach –0.03, –0.11, and –0.18, respectively; the corresponding z-values reach –0.475, –1.606, and –2.580. Table 6.13 summarizes the correlation coefficients between SSTs (Nino 3.4 and first Principal Component of the Indo-Pacific SST

52

anomalies) and all-type cloud amount anomalies for the selected months. Only those correlation coefficients that are significant at a 0.05 significance level are highlighted in bold.

Table 6.13. Correlation coefficients (R) between sea surface temperatures and all-type cloud amounts

Time Series CA Anomaly R (z-value)

January February July August

Nino 3.4 SST

January -0.770 (-3.175) February -0.213 (-0.880) July +0.125 (+0.514) August +0.004 (+0.017)

PC1 30°S-30°S Indo-Pacific SST Anomaly

January* +0.848 (+3.497) February +0.160 (+0.658) July +0.179 (+0.737) August -0.069 (-0.286)

*For the tropical belt 15°S-15°N, the correlation coefficient and the z-value reach, respectively, -0.843 and -3.477. Data of sunshine: Figure 6.34 depicts the estimated trends in the mean (confirmatory analysis) of total annual sunshine (SR1) and total annual foggy days (SR2) for the selected spatial domain. The spatial distribution of the estimated trends in the total number of sunny days, daily maximum sunshine, daily minimum sunshine, daily mean sunshine, and standard deviation of daily sunshine are available in the back-up of these analyses. As previously discussed, the data of sunshine for the selected spatial domain exhibit four particular patterns: (a) the annual cycles observed at weather stations located at lower levels on the Western flank of the ACMR; (b) the intra-annual cycles that characterize the area in the proximity of the met station XVI El Cedral (2,120 m); (c) the annual cycles observed at the weather station I Las Brisas, located at higher levels on the Western flank of the ACMR (4,150 m); and (d) the distributions exhibited by records gathered at lower levels on the Eastern flank of the ACMR. The total annual sunshine (SR1) observed at lower levels (altitudes from 1,026 to 2,080 m) on the Western flank of the ACMR ranges from 1,330 to 1,750 hours per year, approximately. In the area of El Cedral, SR1 reaches a total amount of c.a. 920 hours/year. At higher levels, SR1 exhibits an estimated value of 760 hours/year. At lower levels on the Eastern flank of the ACMR, SR1 ranges from 1,550 to 1,600 hours/year. Table 6.14 summarizes the observed values for SR1, the total number of foggy days (SR2), the total number of sunny days (TSD), the daily maximum sunshine (SR4), the daily mean sunshine (SR5), the daily minimum sunshine (SR6), and the standard deviation of daily sunshine (SR7).

Table 6.14. Annual values of sunshine variables

Area SR1

[hrs/year] SR2

[days/year] TSD

[days/year] SR4

[hours/day] SR5

[hours/day] SR6

[hours/day] SR7

[hours/day]

Lower levels on the Western flank of the ACMR 1,330 to 1,750 8 to 11 344 to 357 8.9 to 9.5 4.1 to 4.9

0.27 to 0.38

2.4 to 2.6

Area in the proximity of the met station XVI El Cedral 920 21 330 6.7 2.6 0.09 1.78

Higher levels on the Western flank of the ACMR 760 53 268 8.1 2.5 0.01 2.3

Lower levels on the Eastern flank of the ACMR 1,550 to 1,600 12 341 to 351 9.4 to 9.6 4.3 to 4.6

0.22 to 0.27

2.6 to 2.7

53

75°20’75°30’ 75°10’75°40’75°50’

04°50’

04°40’

04°30’

05°00’

05°10’

VI

VII

VIIIIX

LONGITUDE [W]

LA

TIT

UD

E [

N]

II

X

XI

I

1

2

4

5

6

7

8

9

XIIXIII

XIVXV

XVI

XVII

XIX

10

311

XX

XXI

XXII

XXIII

XXIV

XXV

XXVIXVIII

III, IV, V

SR1SR1

+4<+3

%/decade

+8

-4<-3 -8

Ψ

Ψ

Ψ

Ψ

Ψ

Ψ

Ψ

NO TRENDΨ

75°20’75°30’ 75°10’75°40’75°50’

04°50’

04°40’

04°30’

05°00’

05°10’

VI

VII

VIIIIX

LONGITUDE [W]

LA

TIT

UD

E [

N]

II

X

XI

I

1

2

4

5

6

7

8

9

XIIXIII

XIVXV

XVI

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XIX

10

311

XX

XXI

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XXIII

XXIV

XXV

XXVIXVIII

III, IV, V

+1.<+.5

days/decade

+3.

-1.<-.5 -3.

Ψ

Ψ

Ψ

Ψ

SR2SR2

NO TRENDΨ

Figure 6.34. Estimated trends in the mean (confirmatory analysis) of total annual sunshine (SR1; top panel) and total annual foggy days (SR2; bottom panel) for the selected spatial domain (04°25’N-05°15’N and 75°00’W-76°00’W). Trends are significant at a 95% confidence level. Circles denote the location of weather stations with available info. Yellow solid line delineates the perimeter of the Los Nevados Natural Park; grey solid line shows the Claro River’s high altitude basin.

54

Data of rainfall: The lower levels on the Western flank of the ACMR exhibit total rainfall amounts (R1) in the range from 1,800 to 2,700 mm/year approximately. At higher levels, the amounts are below 2,000 mm/year and can decrease to almost 1,100 mm. Weather stations located on the Eastern flank show annual records that range from 1,900 to 2,300 mm at lower levels, and from 990 to 1,800 mm at higher levels. Table 6.15 summarizes the observed values of R1, the total number of dry days (R2), and the average maximum daily rainfall (R3).

Table 6.15. Annual values of rainfall variables

Area R1 [mm/year]

R2 [days/year]

R3 [mm/day]

Lower levels on the Western flank of the ACMR 1,800 to 2,700 106 to 187 42.7 to 48.0

Higher levels on the Western flank of the ACMR 1,100 to 2,000 120 to 173 19.5 to 31.7

Lower levels on the Eastern flank of the ACMR 1,900 to 2,300 153 45.7

Higher levels on the Eastern flank of the ACMR 990 to 1,800 193 to 199 18.1 to 32.3

Figure 6.35 depicts the estimated trends in the mean (confirmatory analysis) of the total annual rainfall (R1) and the total number of dry days per year (R2) for the selected spatial domain. The spatial distribution of the estimated trends in the average maximum daily rainfall (R3) is available in the back-up of these analyses. Data of minimum temperatures: Figure 6.36 depicts the estimated trends in the mean (confirmatory analysis) of the ‘average’ minimum temperatures (ATmin) and the minimum temperatures observed during the coldest days (mTmin2) for the selected spatial domain. The spatial distribution of the estimated trends in minimum temperatures observed during the warmest days (MTmin) and the standard deviation of minimum temperatures (SDTmin) are available in the back-up of these analyses. Annual values of MTmin in the region exhibit values ranging from 3.0 to 18.6°C and follow the linear trend given by MTmin=24.044–0.0049 H (R2=0.8752), where H denotes the altitude above sea level expressed in [m]. Annual values of mTmin2 exhibit values ranging from -1.5 to 15.3°C, and follow the linear trend mTmin2=21.418–0.0054 H (R2=0.9262). Minimum annual temperatures observed under ‘average’ conditions (ATmin) in the spatial domain range from 1.2 to 17.2°C. Finally, the day-to-day standard deviation of minimum temperatures shows values in the range [0.8-1.0°C]. Data of maximum temperatures: Figure 6.37 depicts the estimated trends in the mean (confirmatory analysis) of the ‘average’ maximum temperatures (ATmax) and the maximum temperatures observed during the warmest days (MTmax) for the selected spatial domain. The spatial distribution of the estimated trends in maximum temperatures observed during the coldest days (mTmax2) and the standard deviation of maximum temperatures (SDTmax) are available in the back-up of these analyses. Annual values of MTmax in the region exhibit values ranging from 11.6 to 30.6°C and follow the linear trend MTmax=36.123–0.0059 H (R2=0.8428). Annual values of mTmax2 exhibit records ranging from 5.5 to 23.5°C, and follow the linear trend mTmax2=28.809–0.0055 H (R2=0.8586). Maximum annual temperatures observed under ‘average’ conditions (ATmax) in the selected spatial domain range from 8.4 to 27.7°C. Finally, the day-to-day standard deviation of maximum temperatures shows values in the range [1.2-1.9°C].

55

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Figure 6.35. Estimated trends in the mean (confirmatory analysis) of the total annual rainfall (R1; top panel) and the total number of dry days per year (R2; bottom panel) for the selected spatial domain (04°25’N-05°15’N and 75°00’W-76°00’W). Trends are significant at a 95% confidence level. Circles denote the location of weather stations with available info. Yellow solid line delineates the perimeter of the Los Nevados Natural Park; grey solid line shows the Claro River’s high altitude basin.

56

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Figure 6.36. Estimated trends in the mean (confirmatory analysis) of ‘average’ minimum temperatures (ATmin; top panel) and minimum temperatures observed during the coldest days (mTmin2; bottom panel) for the selected spatial domain. Trends are significant at a 95% confidence level.

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Figure 6.37. Estimated trends in the mean (confirmatory analysis) of ‘average’ maximum temperatures (ATmax; top panel) and maximum temperatures observed during the warmest days (MTmax; bottom panel) for the selected spatial domain. Trends are significant at a 95% confidence level.

58

Data of relative humidity: Figure 6.38 depicts the estimated trends in the mean (confirmatory analysis) of mean relative humidity values (ARH) and minimum relative humidity values (mRH2) observed in the selected spatial domain. The spatial distribution of the estimated trends in maximum relative humidity values (MRH) and the standard deviation of relative humidity (SDRH) are available in the back-up of these analyses. Annual maximum relative humidity records (MRH) range from 90.2 to 98.2%. Annual values of ARH in the region range from 74.5 to 91.6%. Annual values of mRH2 range from 62.7 to 77.1%. Finally, the day-to-day standard deviation of relative humidity shows values ranging from 4.8 to 7.2%.

Data of diurnal temperature range: Figure 6.39 depicts the estimated trends in the mean (confirmatory analysis) of maximum (MDTR) and mean (ADTR) diurnal temperature range observed in the selected spatial domain. The spatial distribution of the estimated trends in minimum diurnal temperature range (mDTR2) and the day-to-day standard deviation of the diurnal temperature range (SDDTR) are available in the back-up of these analyses. Records of annual maximum diurnal temperature range show values varying from 9.3°C on the Eastern flank of the ACMR to 14.7°C on the Western flank. At higher altitudes, MDTR values show an annual mean of about 11.3°C. Annual values of ADTR in the region range from 6.6 to 11.0°C; at higher altitudes, the mean diurnal temperature range reaches 7.2°C. Annual values of mDTR2 range from 3.6 to 6.3°C; mDTR2 records collected at higher altitudes show the lowest values of the annual average observed in the region. Finally, the day-to-day standard deviation of the diurnal temperature range shows values ranging from 1.4°C on the Eastern flank of the ACMR to 2.1°C on the Western flank. Data of potential evaporation: Records of annual potential evaporation on the Western flank of the ACMR show values ranging from 700 mm per year at higher altitudes to almost 1,400 mm/year at lower levels. Data of dew point: records of mean annual dew point observed at the weather station VI Apto Matecana show a historical value of 17.0+0.5°C. Data of vapor pressure: records of actual vapor pressure observed at the weather station VI Apto Matecana show a historical value of 19.4+0.6 *102*kg/m/s2. Data of cloud cover (observed from the ground): records of cloud amounts observed from the ground at the weather station 11 Apto La Nubia show a mean annual historical value of 5.8 octants. Data of wind speed/direction: records of wind speed observed at the weather station 11 Apto La Nubia show a mean annual historical value of 2.9 m/s. Based on 49 months of data, wind direction is likely to be NW (approximately 80% of the months); 12% and 8% of the months wind blew from the West and the Southwest, respectively.

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Figure 6.38. Estimated trends in the mean (confirmatory analysis) of mean relative humidity (ARH; top panel) and minimum relative humidity (mRH2; bottom panel) observed in the selected spatial domain. Trends are significant at a 95% confidence level.

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Figure 6.39. Estimated trends in the mean (confirmatory analysis) of maximum (MDTR; top panel) and mean (ADTR; bottom panel) diurnal temperature range observed in the selected spatial domain. Trends are significant at a 95% confidence level.

61

Figure 6.40 depicts the annual values and long-term trends of total sunshine and total rainfall observed in the selected spatial domain. Total annual sunshine values gathered at most of the weather stations located on the Western flank of the ACMR exhibit statistically significant decreasing trends at altitudes around the pluviometric optimum (ca. 1,500 m) that range from –3.7 to –8.5%/decade. Weather stations located above the optimum do not show increasing/decreasing trends. The decreases in sunshine are consistent with statistically significant increases in the total number of foggy days (and decreases in the total number of sunny days) of about 1-3 days/decade that are observed at the same weather stations. Daily maximum, mean and minimum sunshine values observed at lower altitudes also exhibit decreases of about 0.1 to 0.4, 0.2 to 0.4, and <0.1 to 0.1 hours/day/decade, respectively. Finally, in only two weather stations the standard deviation of daily sunshine shows statistically significant trends; the rates of decrease reach 0.04 and 0.06 hours/day/decade. Total annual rainfall amounts show statistically significant decreasing trends ranging from –7.0 to –11.0%/decade in some met stations located at altitudes above the pluviometric optimum and particularly over the Western flank of the ACMR. Below this level, the historical time series of only two weather stations exhibit slow increasing trends of about 3-4%/decade. Most of the weather stations gathering the total number of dry days do not show statistically significant increasing/decreasing trends. Finally, maximum daily precipitation records suggest an increased occurrence of unusually heavy rainfall events, particularly over the Western flank of the ACMR; trends in the mean reach +3-4%/decade.

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Figure 6.40. Annual values and long-term trends of sunshine (left panel) and total rainfall (right panel) observed in the spatial domain (04°25’N-05°15’N and 75°00’W-76°00’W). Trends are expressed in %/decade. Figure 6.41 depicts the annual values and long-term trends of minimum temperatures observed on the warmest (MTmin) and coldest (mTmin2) days in the selected spatial domain. MTmin records exhibit statistically significant trends at altitudes below 2,500 m that range from +0.10 to +0.50°C/decade. Records gathered at Las Brisas weather station at higher altitudes do not show a significant trend. Minimum annual temperatures under ‘average’ conditions (ATmin, not shown in Figure 6.41), gathered at weather stations located below 2,500 m, exhibit increasing trends that range from +0.10 to +0.60°C/decade. Records of ATmin observed at Las Brisas weather station do not show a significant trend. Minimum temperatures observed on the coldest days (mTmin2) exhibit statistically significant increasing trends at all altitudes (including Las Brisas met station) that range from +0.10 to +0.90°C/decade. It is worth to mention that increases in these extreme minimum temperatures at higher levels are more than twice (2.1) of what is observed in average at lower altitudes. Finally, on the Western flank only two weather stations exhibit increasing trends in the day-to-day standard deviation of minimum temperatures of about 0.1°C/decade.

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Figure 6.41. Annual values and long-term trends of minimum temperatures observed on the warmest days (left panel) and on the coldest days (right panel) in the spatial domain (04°25’N-05°15’N and 75°00’W-76°00’W). Trends are expressed in °C/decade. Figure 6.42 depicts the annual values and long-term trends of maximum temperatures observed on the warmest (MTmax) and coldest (mTmax2) days in the selected spatial domain. MTmax records exhibit statistically significant trends at all altitudes that range from +0.20 to +1.50°C/decade. Increases in maximum temperatures observed on the warmest days at higher levels are more than three times (3.6) of what is observed in average at lower altitudes. Maximum annual temperatures gathered under ‘average’ conditions (ATmax, not shown in Figure 6.42) exhibit increasing trends that range from +0.10 to +0.60°C/decade at all altitudes. Maximum temperatures observed on the coldest days (mTmax2) exhibit statistically significant increasing trends in only three weather stations: El Cedral, La Trinidad y Las Brisas. Their increasing trends in the mean reach +0.20, +0.30, and +0.90°C/decade, respectively. Finally, the day-to-day standard deviation of maximum temperatures shows increasing trends as high as 0.3°C/decade.

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Figure 6.42. Annual values and long-term trends of maximum temperatures observed on the warmest days (left panel) and on the coldest days (right panel) in the spatial domain (04°25’N-05°15’N and 75°00’W-76°00’W). Trends are expressed in °C/decade.

63

Figure 6.43 depicts the annual values and long-term trends of mean (ARH) and minimum (mRH2) relative humidity values observed in the selected spatial domain. Statistically significant trends in maximum relative humidity values (MRH, not shown in Figure 6.43) are only seen in the historical records of Las Brisas, Santagueda and El Jazmin weather stations. Estimated historical trends reach -2.2 (higher altitudes), +3.0 and 2.4% (lower altitudes) per decade, respectively. Mean annual relative humidity values exhibit statistically significant decreasing trends at altitudes above the pluviometric optimum that range from –1.5 to –3.6% per decade. Some weather stations located at altitudes around and below this pluviometric threshold show slight statistically significant increasing trends of about +0.6 to +0.7%/decade. Finally, minimum relative humidity values exhibit statistically significant decreasing trends that range from -3.2 to -8.7%/decade. Only one weather station, Cenicafe, shows records with an increasing trend of about +1.2%/decade. Finally, the day-to-day standard deviation of relative humidity shows trends in only three weather stations of about 1.1-1.5 %/decade.

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Figure 6.43. Annual values and long-term trends of mean (left panel) and minimum (right panel) relative humidity values observed in the spatial domain (04°25’N-05°15’N and 75°00’W-76°00’W). Trends are expressed in %/decade. Statistically significant trends in maximum diurnal temperature range are observed in five weather stations gathering this variable. At higher levels, trends are positive and reach rates of increase of 0.4-1.2°C/decade; at lower levels, records exhibit decreasing trends of about 0.2-0.4°C/decade. Figure 6.44 depicts the annual values and long-term trends of the mean diurnal temperature range (ADTR) observed in the selected spatial domain. The estimated historical trends reach +0.3 and +1.3°C/decade at altitudes above 2,000 m, and -0.2 and -0.3°C/decade at altitudes in the range [1,000-2,000 m]. Minimum diurnal temperature range exhibit statistically significant trends of about 1.0°C/decade at higher altitudes, and decreasing trends of about 0.1-0.3°C/decade at altitudes below 2,000 m. Finally, records of only two weather stations (XV Santagueda y XVI El Cedral) exhibit trends in the day-to-day standard deviation of the diurnal temperature range; the rate of increase reaches 0.1°C/decade. Only three of the available met stations have EVP historical records with sample sizes greater than 15 years. Met stations 11 Apto La Nubia and VI Apto Matecana have 16 and 19 years of available records, respectively; both of them show statistically significant increasing trends that exceed 8%/decade (see Figure 6.44). Met station XX Veracruz has 18 years of data; EVP records at this weather station do not exhibit a significant trend.

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Figure 6.44. Annual values and long-term trends of the mean diurnal temperature range (left panel) and total annual potential evaporation observed in the spatial domain (04°25’N-05°15’N and 75°00’W-76°00’W). Trends are expressed in °C/decade and %/decade, respectively. Dew point and vapor pressure records gathered at the weather station VI Apto Matecana show statistically significant decreasing trends of about –0.1°C/decade and –0.2*102*kg/m/s2/decade, respectively. Finally, since data are limited for the analyses statistical tests were not conducted for detecting significant trends in the mean of cloud cover, wind speed and wind direction.

signals of climate variability/change in surface water...

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