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CHG rainfall productsMake best possible rainfall products for monitoring crop
stress in areas of rain fed agriculture.Objectives:
CHG rainfall productsMake best possible rainfall products for monitoring crop
stress in areas of rain fed agriculture.
Results:
Objectives:
CHIRP (1981 - present) and FTIP (2000 - present)
Global unbiased 0.05 degree pentads
available with 2 day lag
tinyurl.com/chg-products
CHG rainfall productsMake best possible rainfall products for monitoring crop
stress in areas of rain fed agriculture.
Improved Results:
Objectives:
CHIRP/FTIP blended with station data, 1 pentad lag
Results: CHIRP (1981 - present) and FTIP (2000 - present)
Global unbiased 0.05 degree pentads
available with 2 day lag
tinyurl.com/chg-products
Quick overview of how we get there…
• Start with long term monthly average rainfall maps FCLIM• Aside: build monthly models of rainfall trained on TRMM-V7
– derive coefficients a and b, such that rain rate = a * CCD + b (IRP)– where CCD is the percentage of observation where IR temp < threshold
• Calculate IRP pentads from CPC IR data (2000 - present) and B1 IR data (1981 - 2008)
• CHIRP (1981-present) = FCLIM * (IRP %normal)
• Use TRMM-RT7 data (2000 - present)
• FTIP (2000-present) = FCLIM * (IRP %normal + TRMM-RT7 %normal)/2
• SPACE TIME
Validation analysis
• for each data set to validate, CHIRP, FTIP, TRMM, ECMWF…• build cubes of 2 month totals based on growing season.
Season time series (2001 – 2011) JFM [J1+F1, J1+M1, F1+M1, …, J11+F11, J11+M11, F11+M11]. . . JAS [J1+A1, J1+S1, A1+S1, …, J11+A11, J11+S11, A11+S11]. . . NDJ [N1+D1, N1+J2, D1+J2, …, N11+D11, N11+nan, D11+nan]
longitude latitude
time
ser
ies
longitude latitude
time
ser
ies
‘True’ FTIP
correlation
bias ratio
mean absolute error
misses
CHG Station Climate Database
• Daily rainfall observations from many public and private sources going back to the 1800’s
• Currently ~950,000 records in db• Used to create spatially interpolated fields• Challenge identifying duplicates, non-zero zeroes• Constantly topping off db from available sources• Blended into satellite rainfall products
Summary
• 2 rainfall products, CHIRP (1981-present) & FTIP (2000-present)
• Global, 0.05º, unbiased, pentads with 2 day lag.
• Compare very well with existing rainfall products.
• Developing an extensive station rainfall database• Used to blend station data with CHIRP and FTIP
Thank You …• Chris Funk• Greg Husak• Joel Michaelsen• Diego Pedreros• Andrew Verdin• Marty Landsfeld• Boleslo Romero• FEWS NET
• Data available via anonymous ftp: tinyurl.com/chg-products
CHG Rainfall Product Paths
FCLIM
CHG Stations database
FTIPS2005-prst, 5Km, 5days
CCD model
IRP2000-prnt
BIRP1980-2008
Join 80-prst
CHIRPCHIRPS1980-present, 5Km, 5days
FTIP
FCLIMS, 1920 present, 5Km, 5days
Source Datasets
Station Average monthly rainfall
Rainfall predictors
TRMM7-RT 2000-prsnt
IR-B1 1980-2008
CPC-IR – 2000-prsnt
TRMMV71998-present
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