Recent improvements in a method for remotely sensing precipitation and latent heating distributions based upon satellite-borne, passive microwave radiometer observations are summarized. In applications to synthetic data, estimated rainfall rates at sensor footprint-scale (14 km) are subject to significant random errors, but these errors are substantially reduced by spatial averaging. After spatial-averaging, rain rate and latent heating profile estimates exhibit biases that arise from a lack of specificity in the information contained in the microwave radiance data.
The retrieval method is applied to observations from the Tropical Rainfall Measuring Mission Microwave Radiometer (TMI). Retrieved instantaneous precipitation and heating distributions show general self-consistency and delineate plausible storm structures in an application to TMI observations of a mesoscale convective system over the tropical North Atlantic. Well-known climatological distributions of rainfall are reproduced by global, monthly-mean TMI precipitation estimates from July 2000. Zonal-mean heating profiles in the Tropics from the same period exhibit a primary maximum of heating near 7 km altitude and a secondary peak near 3 km, while at higher latitudes in the Southern Hemisphere, a vertical structure with heating aloft and cooling at lower altitudes is derived.
A primary goal of the South China Sea Monsoon Experiment (SCSMEX, 1998), a major field campaign of Tropical Rainfall Measuring Mission (TRMM), is to define the initiation, structure, evolution and dynamics of precipitation processes associated with the onset of the South China Sea (SCS) summer monsoon. Information from SCSMEX will be used for initialization and validation of cloud-resolving models and passive microwave retrieval algorithms. In this study, dual-Doppler radar analysis technique combining with the polarimetric radar data analysis are used to investigate the development and structure of a vigorous squall line system observed on 24 May 1998. Comparing to the tropical squall lines observed in other regions, this narrow squall line system had some interesting features including: 1) with maximum reflectivity over 55 dBZ, this squall line system has little stratiform rain, 2) the small area of stratiform rain was ahead instead of trailing to the convective line, and 3) rather than a narrow ribbon of vertical velocity maximum near the leading edge, this system has an elongate vertical velocity maximum in the rear part of the system. Polarimetric radar inferred microphysical and rainfall properties are placed in the context of the mesoscale morphology and dual-Doppler derived kinematics for this vigorous squall line.