Retrieval of raindrop and cloud particle size distributions with 14 GHz and 95 GHz radars

Abstract

We have developed a sequential algorithm to retrieve vertical profiles of cloud and rainfall microphysical information from radar reflectivities of a 14 GHz precipitation radar, and a 95 GHz cloud-profiling radar. This sequential algorithm retrieves the number density NT, the mean volume diameter Dm and the liquid water content LWC from the nearest to the farthest ranges considering the significant attenuation and Mie scattering. To avoid the accumulation of numerical errors, the retrieval is computed in adjacent ranges assuming NT to be constant in each pair. We demonstrate that our method retrieves NT and Dm stably, even if the raindrop size distribution is different from our assumption, or even if some bias errors are appended to the radar constant. The method is applied to collocated ground-based observation by a 14 and a 95 GHz radar, and the retrieved results are evaluated by comparing them against disdrometer-derived size distributions, where the rainfall rate was from 0.1 to 4.6 mm/hr. The retrieved Dm, and the disdrometer-derived Dm, agree to within 30%. The retrieved log10 LWC, and the disdrometer-derived log10 LWC, also agree to within 30% when the rainfall rate is greater than 0.5 mm/hr. © 2005, Meteorological Society of Japan.