The development and structure of an oceanic squall line system during the South China Sea Monsoon Experiment

A primary goal of the South China Sea Monsoon Experiment (SCSMEX, 1998), a major field campaign of the 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. In this study, dual-Doppler and dual polarimetric radar analysis techniques are used to investigate the development and structure of a vigorous squall line system observed on 24 May 1998.

Polarimetric radar inferred microphysical (e.g., hydrometeor type, amount, and size) and rainfall properties are placed in the context of the mesoscale morphology and dual-Doppler derived kinematics for this squall line system. A comparison is made between results from this study for SCSMEX and the previous studies for TRMM Large-Scale Biosphere-Atmosphere experiment (LBA). We found that precipitation over the SCS monsoon region during the summer monsoon onset was similar to the precipitation over the Amazon monsoon region during the westerly regime of the TRMM-LBA, which has previously been found to be closer to typical conditions over tropical oceans. Both of these cases showed lower rain rates and rainwater contents, smaller raindrops, and significantly lower ice water contents between 5 km and 8 km than the precipitation over the Amazon during the easterly regime of the TRMM-LBA with more tropical continental characteristics.