The development of rainfall retrievals from radar at Darwin

Abstract. The U.S. Department of Energy Atmospheric Radiation Measurement program Tropical Western Pacific site hosted a C-band polarization (CPOL) radar in Darwin, Australia. It provides 2 decades tropical rainfall characteristics useful for validating global circulation models. Rainfall retrievals from assume about the droplet size distribution (DSD) that vary significantly. To minimize uncertainty associated with DSD variability, new techniques use dual and specific attenuation estimates. This study challenges applicability several dual-polarization-based estimators settings using 4-year archive Darwin disdrometer datasets conjunction CPOL observations. assessment is based on three metrics: statistical estimates, principal component analysis (PCA), comparisons various data. PCA shows variability R can be consistently attributed to reflectivity, but dependence dual-polarization quantities was wavelength dependent 1<R<10mmh-1. These rates primarily originate stratiform clouds weak convection (median drop diameters less than 1.5 mm). differential phase reflectivity increase usefulness times R>10mmh-1. estimates during these conditions deep convective median greater mm. An intercomparison show Colorado State University blended technique oceans, modified developed video observations, most appropriate all cases, such as when 1<R<10mmh-1 (stratiform rain) R>10mmh-1 (deeper rain).