permafrost data muot da barba peider - some first analyses – evelyn zenklusen
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Permafrost data Muot da Barba Peider - some first analyses – Evelyn Zenklusen. CCES-Extremes Meeting, 30.04.2008, EPFL. Outline. What is permafrost Motivation Borehole temperature measurements First analyses Summary & future plans. cliffs 0 bis ? %. What is permafrost ? Definition. - PowerPoint PPT PresentationTRANSCRIPT
Permafrost data Muot da Barba PeiderPermafrost data Muot da Barba Peider- some first analyses –- some first analyses –
Evelyn ZenklusenEvelyn Zenklusen
CCES-Extremes Meeting, 30.04.2008, EPFL
OutlineOutline
• What is permafrost
• Motivation
• Borehole temperature measurements
• First analyses
• Summary & future plans
What is permafrost ?What is permafrost ?
DefinitionDefinition
permafrost or permafrost soil
- soil at or below the freezing point of water (0 °C) for two or more years.
- ice is not always present, but it frequently occurs
- most permafrost is located in high latitudes, but alpine permafrost may exist at high altitudes in much lower latitudes.
rock glaciers ~80% vol.
cliffs 0 bis ? %
detritus ~10%Photos:
Marcia Phillips
What is permafrost ?What is permafrost ?
Permafrost profilePermafrost profile
MotivationMotivation
thawing permafrost ...
- problems with buildings & constructions (settlements, liftings) - natural hazards (rock slides, debris flows, creeping processes)
Photo: Markus Walser
Photo: Marcia Phillips
Borehole temperature measurementsBorehole temperature measurements
Borehole locations, Muot da Barba Peider
(2980 m ASL, Pontresina, E Swiss Alps)
Logger
Temperature measurementsinside the borehole:0.5m, 1.0m, 2.0m, 3.0m, 4.0m,6.0m, 8.0m, 10.0m, 13.5m, 17.5m
First anlaysesFirst anlayses
Borehole temperatures: observation Borehole temperatures: observation seriesseries
Borehole temperatures Muot da Barba Peider (2980 m.a.s.l.) 04.10.1996-16.07.2007te
mp
era
ture
[°C
]
-6-4
-20
2
19970101 19980101 19990101 20000101 20010101 20020101 20030101 20040101 20050101 20060101 20070101
X0.5.mX1.0.mX2.0.mX3.0.m
X4.0.mX6.0.mX8.0.mX10.0.m
X13.5.mX17.5.m
annual cycle: problem für trend calculation
trend with periodic function
Trend over annual max/min/mean/median/certain day
First anlaysesFirst anlayses
Trend analysis of 1st January temperatureTrend analysis of 1st January temperature
1998 2000 2002 2004 2006
-5-4
-3-2
-10
X0.5.m
tem
pe
ratu
re [°
C]
Trend: -0.0065°C, P-Wert: 0.9583
1998 2000 2002 2004 2006
-5-4
-3-2
-10
X6.0.m
tem
pe
ratu
re [°
C]
Trend: 0.0353°C, P-Wert: 0.0399
1998 2000 2002 2004 2006
-5-4
-3-2
-10
X17.5.m
tem
pe
ratu
re [°
C]
Trend: 0.0329°C, P-Wert: 1e-04
• linear regression• t-test• analogue analyses for annual mean, max, min and median temperatures
• for all: significant increasing temperature trends only in deeper layers• no clear trends in upper layers• short time series!
First anlayses:First anlayses:
Trend analysis for every day of the yearTrend analysis for every day of the year
• deeper layers: significant positive trends• intermediate layers: no clear trends• top layer: positive trends in summer and autumn
tem
pera
ture
tre
nd [
°C]
-0.2
0-0
.15
-0.1
0-0
.05
0.00
0.05
0.10
1st Jan 1st Feb 1st Mar 1st Apr 1st May 1st Jun 1st Jul 1st Aug 1st Sep 1st Oct 1st Nov 1st Dec 31th Dec
X0.5.mX1.0.mX2.0.mX3.0.m
X4.0.mX6.0.mX8.0.mX10.0.m
X13.5.mX17.5.m
significant not significant
First anlayses:First anlayses:
Annual count of thawing daysAnnual count of thawing days
• Thawing day: day with temperature > 0°C
• Logistic regression
• Thawing days only exist in upper levels
• No clear trends visible
Trend in temperature > 0°C of all days
X0.5.m
cou
nt o
f da
ys T
>0
°C
1998 2000 2002 2004 200620
40
60
80
100
rel.trend[%/decade]: 52.9 abs.trend[days/decade]: 32 p-value: 0.2189min: 19 max: 103
X1.0.m
cou
nt o
f da
ys T
>0
°C
1998 2000 2002 2004 200605
101520253035
rel.trend[%/decade]: 180 abs.trend[days/decade]: 6 p-value: 0.5187min: 0 max: 34
X2.0.m
cou
nt o
f da
ys T
>0
°C
1998 2000 2002 2004 2006-1.0
-0.5
0.0
0.5
1.0
rel.trend[%/decade]: 0 abs.trend[days/decade]: 0 p-value: 1min: 0 max: 0
First anlayses:First anlayses:
Cumulative ground temperaturesCumulative ground temperatures
• for every year: add up daily temperature
• hydrological year: 1st Nov – 31th Oct
• keep in mind:
– early & snowy winter 2001 (snow cover 01.11.2000 -12.07.2001)
– hot summer 2003 (snow-free 17.06.2003 – 03.09.2003)
influence of snow and temperature on permafrost
First anlayses:First anlayses:
Cumulative ground temperaturesCumulative ground temperatures
X0.5.m (hydrological year)
month
cum
ula
tive
gro
un
d te
mp
era
ture
[°C
]
N D J F M A M J J A S O
-80
0-6
00
-40
0-2
00
0
19971998199920002001
20022003200420052006
20020011
20020033
First anlayses:First anlayses:
Cumulative ground temperaturesCumulative ground temperatures
X2.0.m (hydrological year)
month
cum
ula
tive
gro
un
d te
mp
era
ture
[°C
]
N D J F M A M J J A S O
-80
0-6
00
-40
0-2
00
0
19971998199920002001
20022003200420052006
20020011
20020033
First anlayses:First anlayses:
Cumulative ground temperaturesCumulative ground temperatures
X4.0.m (hydrological year)
month
cum
ula
tive
gro
un
d te
mp
era
ture
[°C
]
N D J F M A M J J A S O
-80
0-6
00
-40
0-2
00
0
19971998199920002001
20022003200420052006
20020011
20020033
First anlayses:First anlayses:
Cumulative ground temperaturesCumulative ground temperatures
X10.0.m (hydrological year)
month
cum
ula
tive
gro
un
d te
mp
era
ture
[°C
]
N D J F M A M J J A S O
-80
0-6
00
-40
0-2
00
0
19971998199920002001
20022003200420052006
2002001120020033
First anlayses:First anlayses:
Cumulative ground temperaturesCumulative ground temperatures
X17.5.m (hydrological year)
month
cum
ula
tive
gro
un
d te
mp
era
ture
[°C
]
N D J F M A M J J A S O
-80
0-6
00
-40
0-2
00
0
19971998199920002001
20022003200420052006
20020011
20020033
Summary & future plansSummary & future plans
• Trend over observation series, annual cycle trend with periodic function
• Extreme values (limited data base with annual min/max) trend for data over threshold
• Link permafrost temperature with snow cover and air temperature
• Look at other boreholes
allocated in Switzerland