Recent FEWS NET research

i) Cropped Area

ii) Improved Rainfall Estimates

iii) Climate Change Analyses

TM to Hi-Res Comparison

High Resolution imagery used to classify dots spaced at 500m intervals, and represent “truth”

Field photos provided by USDA give a ground-view of landscape

TM with classification

Quickbird with classification

Mathematical Comparison

• TM tends to systematically overestimate cropped area

• Assessing the relationship between TM cropped area and ‘true’ cropped area reveals an approximately linear relationship

• R^2 = 0.62• For our tested locations cropped area is

20.1% +/- 1.9%

HRTM 46.0%

Improved RFE Estimates (IRE)

ARC MeansSlopeElevationClimate Normals

regressionEnhanced MonthlyMean Fields RFE %s

Multiplication

Unbiased Rainfall Estimates

IDW

Station Data

Improved Rainfall Estimates(IRE)

Mean Fields Comparison

• R=0.8 at 0.1°• Bias=0.01 mm

Much better mean fields than the CHARM

N=73 n=19

Driven by GPCP

MAM

Western Kenya Temporal Error Validation

Driven by GPCP

Regional Metrics At-pixel metrics

Spatial R2

MBE MAE MAESTD-1

TimeR2

MAE MAESTD-1

TimeR2

Seasonal 0.67 0.01 8 0.31 0.87 26 0.52 0.54

Monthly 0.64 0.00 14 0.37 0.75 39 0.54 0.49

Monthly March, Apriland May Observations

SPI Regression Maps

• Compare 1979-2005 IRE SPI values

• 2 predictors– Southwest

Indian Ocean Precip

– Indian Ocean Dipole

850 MAM winds

Concerning TrendsDry Tanzania/Kenya/Ethiopian MAM SPI

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

3

Year

SP

I