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

CHIRP 2012.09.60.05º, global, unbiased, rainfall pentad [mm] with 2 day lag.

FTIP 2012.09.60.05º, 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

• 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

Correlation with interpolated stations

-0.5 0.0 0.5 0.7 1.0

TRMM-RT7 ECMWF

CHIRP FTIP

Bias ratio to interpolated stations

0.0 0.5 0.8 1.2 1.5 >1.5

TRMM-RT7 ECMWF

CHIRP FTIP

Mean Absolute Error with interpolated stations

0 40 60 100 >100

TRMM-RT7 ECMWF

CHIRP FTIP

Misses compared to interpolated stations

0 1 4 9 >9

TRMM-RT7 ECMWF

CHIRP FTIP

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

January 2009 Original

January 2009 Fixed

B1 fails 2

B1 fails 3

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