Brigham Young University DGL Dec 03 Rain/Wind Backscatter Model  Model for measured backscatter  Radar signal scattered by falling droplets  Surface signal attenuated by atmospheric rain  Surface wind-induced backscatter perturbed by rain striking the water  Model derived from colocated TRMM PR and QuikSCAT data Rain affects ~4% of SeaWinds data

Brigham Young University DGL Dec 03 Simultaneous Wind/Rain Retrieval

Brigham Young University DGL Dec 03 Wind Rain Regimes  Regime 1: rain dominates wind backscatter – poor quality wind estimates (10% of rain cases*)  Regime 2: both wind and rain important – can retrieve wind and rain rate (34% of rain cases*)  Regime 3: rain effects insignificant – wind estimates unaffected by rain(56% of rain cases*)  Note: globally, only about 4% of all QuikSCAT data effected by rain * From collocated TRMM PR and QuikSCAT data in tropics  incorporates surface rain perturbation, atmospheric rain scattering, and attenuation - Empirical function of rain rate derived from collocated QuikSCAT and TRMM PR

Brigham Young University DGL Dec 03 Wind/Rain Validation

Brigham Young University DGL Dec 03 Scatterometer Rain Retrieval Validation Bias can be estimated and corrected for

Brigham Young University DGL Dec 03 Rain Estimate Validation  QuikSCAT-derived rain rates vs TMI-derived rain rates

Brigham Young University DGL Dec 03 Storm Example

Brigham Young University DGL Dec 03 Floyd (rev 1201, 11 Sept 1999)

Brigham Young University DGL Dec 03 Typhoon (rev 1222, 12 Sept 1999)