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CHG rainfall products. Make best possible rainfall products for monitoring crop stress in areas of rain fed agriculture. Objectives:. CHG rainfall products. Make best possible rainfall products for monitoring crop stress in areas of rain fed agriculture. Objectives:. Results:.
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CHG rainfall products Make best possible rainfall products for monitoring crop stress in areas of rain fed agriculture. Objectives:
CHG rainfall products Make best possible rainfall products for monitoring crop stress in areas of rain fed agriculture. Objectives: Results: CHIRP (1981 - present) and FTIP (2000 - present) Global unbiased 0.05 degree pentads available with 2 day lag tinyurl.com/chg-products
CHG rainfall products Make best possible rainfall products for monitoring crop stress in areas of rain fed agriculture. Objectives: Results: CHIRP (1981 - present) and FTIP (2000 - present) Global unbiased 0.05 degree pentads available with 2 day lag tinyurl.com/chg-products Improved Results: CHIRP/FTIP blended with station data, 1 pentad lag
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
CHIRP 2012.09.6 0.05º, global, unbiased, rainfall pentad [mm] with 2 day lag.
FTIP 2012.09.6 0.05º, global, unbiased, rainfall pentad [mm] with 2 day lag.
FCLIM derived wet season JFM FMA MAM AMJ MJJ JJA JAS ASO SON OND NDJ DJF
Validation analysis 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] • for each data set to validate, CHIRP, FTIP, TRMM, ECMWF… • build cubes of 2 month totals based on growing season. time series time series FTIP ‘True’ latitude latitude longitude longitude correlation bias ratio mean absolute error misses
TRMM-RT7 ECMWF Correlation with interpolated stations CHIRP FTIP -0.5 0.0 0.5 0.7 1.0
TRMM-RT7 ECMWF Bias ratio to interpolated stations CHIRP FTIP 0.0 0.5 0.8 1.2 1.5 >1.5
TRMM-RT7 ECMWF Mean Absolute Error with interpolated stations CHIRP FTIP 0 40 60 100 >100
TRMM-RT7 ECMWF Misses compared to interpolated stations CHIRP FTIP 0 1 4 9 >9
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 CHG Stations database FCLIMS, 1920 present, 5Km, 5days FCLIM FTIPS 2005-prst, 5Km, 5days FTIP CHIRPS 1980-present, 5Km, 5days CHIRP IRP 2000-prnt Join 80-prst BIRP 1980-2008 CCD model
Some data issues. • B1 glitches • Station zeroes not zero
IDW weights for nearest 3 neighbors mapped to red, green, blue
How to make FAT clims CHIRP clim 09.6 pentad, pixel, = 2176 points/year p-3 p-2 p-1 p p+1 p+2 p+3
FCLIM derived wet season JFM FMA MAM AMJ MJJ JJA JAS ASO SON OND NDJ DJF
CMORPH CPC-Unified PERSIANN Validation - Africa correlations TRMM-V6 TRMM-V7 TRMM-RT7 CHIRP FTIP-V7 FTIP-RT7
CMORPH ECMWF Validation - Correlations red TRMM-RT7 FTIP-RT7 -1.0 0.0 0.5 0.7 1.0
PERSIANN TRMM-V6 Validation - Correlations 2 red TRMM-V7 CHIRP-V7 -1.0 0.0 0.5 0.7 1.0
PERSIANN TRMM-V6 Validation - Correlations 2 blue TRMM-V7 CHIRP-V7 -1.0 0.0 0.5 0.7 1.0
PERSIANN TRMM-V6 Validation - Mean Absolute Error 2 TRMM-V7 CHIRP-V7 0 40 60 100 >100
PERSIANN TRMM-V6 Validation - Bias ratio 2 TRMM-V7 CHIRP-V7 0.0 0.5 0.8 1.2 1.5 >1.5
PERSIANN TRMM-V6 Validation - Misses 2 TRMM-V7 CHIRP-V7 0 1 4 9 >9
TRMM-RT7 ECMWF Correlation with interpolated stations CHIRP FTIP -1.0 0.0 0.5 0.7 1.0
TRMM-RT7 ECMWF Bias ratio to interpolated stations CHIRP FTIP 0.0 0.5 0.8 1.2 1.5 >1.5
TRMM-RT7 ECMWF Mean Absolute Error with interpolated stations CHIRP FTIP 0 40 60 100 >100
TRMM-RT7 ECMWF Misses compared to interpolated stations CHIRP FTIP 0 1 4 9 >9
0.05º, global, unbiased, rainfall pentad [mm] with 2 day lag. CHIRP 2012.09.5
0.05º, global, unbiased, rainfall pentad [mm] with 2 day lag. FTIP 2012.09.5