Variations in drop–size distributions associated with the degree of baroclinicity of the environment

The synoptic-scale environment can have a significant impact on subtropical precipitating systems via the baroclinicity of the environment. In the subtropics, baroclinic environments tend to represent extratropical influences whereas barotropic environments better represent tropical influences, and these different influences can potentially affect the dynamics and microphysical processes that occur in mesoscale systems. The degree of baroclinicity is examined using NCEP reanalysis temperature and zonal wind fields over the course of a year for Southeast Texas, yielding classifications of barotropic, weakly baroclinic and strongly baroclinic for the background environment. Concurrent long-term drop-size distribution measurements from a Joss-Waldvogel disdrometer are then composited by each baroclinicity designation (for individual rain events and monthly averages) to indicate the degree to which the microphysical aspects of mesoscale precipitating systems relate to the dynamics of the large-scale environment.