Retrieval of Thermal and Microphysical Variables in Observed Convective Storms. Part 1: Model Development and Preliminary Testing

Abstract

The air flow in convective storms, the force that regulate the flow, and the processes that produce hydrometeors of various kinds are all being studied intensively by meteorologists using Doppler radar observations. The research reported here proceeds from the observed motion through accompanying thermodynamic and micro-physical processes to the analysis of hydrometer content and thermal fields in thunderstorms. A three-dimensional numerical kinematic cloud model employing Doppler wind fields is developed and used to diagnose temperature and mixing ratios within a thunderstorm. The microphysical parameterization includes stochastic coalescence effects in warm clouds as well as well- and variable-density dry hail growth. Known fields from a dynamically simulated cloud are used to establish the accuracy of the retrieval scheme. Real data tests indicate good agreement between retrieved and observed radar reflectivities, qualitative dynamic consistency between observed winds and retrieved buoyancies, and the model's ability to partition liquid and solid hydrometeors. A modification of weighting factors in the variational multiple Doppler analysis changes the vertical motion field and improves the verification of retrieved reflectivities. This analysis sensitivity emphasizes the great influence of the input wind field on retrieved thunderstorm variables.