crop yield predictions using seasonal climate forecasts simone sievert da costa dsa/cptec/inpe...
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Crop yield predictions using seasonal climate forecasts
SIMONE SIEVERT DA COSTADSA/CPTEC/INPE
simone.sievert@cptec.inpe.br
Second EUROBRISA Workshop July 2009 – Dartmoor, Devon- UK
AimInvestigate the potential of using seasonal climate forecasts for producing maize yield predictions
Crop yield model
Climate Forecast
1000
1500
2000
2500
3000
3500
4000
1989 1991 1993 1995 1997 1999 2001 2003 2005
year
mai
ze g
rain
yie
ld (
kg h
a-1) National Statistics
Maize Grain YieldSource: IBGE
The Study Area
Rio Grande Do Sul State (RS) “Long River of South”
27.2°- 29.8°S/51.2°- 56.0°W
About Maize in RS…After USA and China, Brazil is the main maize producer in the entire world, and RS is the second
greatest producer in Brazil (IBGE, 2006).
Sowing Date: Sep/OctHarvest: Feb/MarchCrop cycle ~130 days
SOIL WATER
TRANSPIRATION
BIOMASS
LEAF CANOPY
ROOT SYSTEM
Water Stress
Transpiration Efficiency
YIELDYIELD
DevelopmentStage
Yield is a time varying fraction of Biomass
Outputs
Yield GapParameter
Daily data required:
Solar Radiation
Min. Temperature
Max. Temperature
Rainfall
Schematic diagram of GLAM (adapted from crop and climate group webpage-Reading)
Crop model: General Large Area Model Challinor et al., 2003
Calibration GLAM was based on observational data (soil and crop phenology). UFRGS, Eldorado do Sul Site, Brazil.
0
1
2
3
4
5
6
7
0 600 1200 1800 2400
degree-days
leaf
are
a in
dex
1993/94
1994/95
1995/96
1996/97
1997/98
1998/99
Muller et al., 2005
GLAM model• Challinor et al. 2003
Morse et al. (2005) Tellus, 57A(3), 464-475
Maize yield predictions
Meteorological stations:Daily data
ECMWF System 3:Anderson et al. (2007)ECMWF Tech. Memo,
503, pp 56
Rain, T, S (climat)
Sim. crop Fcst. crop
Hindcast period: 1989-20050 to 5 month lead predictions; 11 ensemble members
B.corr. RainT, S (climat.)
Seasonal weather data into crop model: Monthly Mean Rainfall ECMWF (bias corrected) forecasts, 11 ensemble members initialized in Sept. (for Sept, Oct, Nov, Dec, Jan, Feb)
Radiation & TemperatureDaily mean observed climatology for wet and dry days (1989 – 2005).
Correlation Between ECMWF monthly Forecasts and Obs. Rainfall Anomalies (1981-2005), Issue Sep.
sept. nov.
dec. jan.
oct.
feb.
Time disaggregation: Monthly mean to daily rainfall using a weather generator
• Stochastic weather generator (first order Markov chain) based on gamma rainfall PDF (Moron, 2005)
• Input data: daily rainfall observations and monthly mean rainfall predictions
• Output data: daily rainfall sequences
Daily Rainfall Histogram for a county - Sept-Feb (1989-2005)
WG (ECMWF)for 2 members
Observation
Daily Rainfall Sequence for All Januaries (1989-2005)
Obs.
WG (ECMWF-Mb. 5)
1989 1994 1999 2004
1989 1994 1999 2004
Daily Rainfall Sequence for All Octobers (1989-2005)
Obs.
WG (ECMWF- Mb. 5)
1989 1994 1999 2004
1989 1994 1999 2004
Grid Point 1
Grid Point 2
fcstobs
Grain yield RS state produced six months in advance
Grain yield prediction for indiv. County
produced six months in advance
3
5
7
Grid Point 1
fcstobs
3
5
7
Grid Point 2
Grain yield predictionfor indiv. County
produced six months in advance
fcstobs
Summary• Stochastic weather generator: powerful tool for
making use of monthly mean rainfall forecasts from coupled seasonal forecast models for producing crop yield predictions
• Preliminary results show promising usefulness of monthly mean rainfall forecasts produced by ECMWF coupled model for producing maize yield predictions for RS six months in advance
Future Directions• Use monthly mean rainfall forecasts from other coupled
models (e.g. CPTEC, UK Met Office and Meteo-France) into weather generator for use in maize yield crop model
• Compared skill of different crop yield forecasts produced using different coupled model monthly mean rainfall forecasts
• Further investigate potential of using seasonal climate forecasts for producing maize yield predictions for other locations (e.g. Uruguay)
Thanks:
• Caio Coelho (CPTEC- Brazil)
• Homero Bergamaschi (UFRGS, Brazil)
• Andrew Challinor (The University of Leeds-UK)
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