Tracking the Evolution of Radar Polarimetric Signatures over the Lifecycle of Isolated Convective Cells: A Four-Year Climatology in the Houston Region

The microphysics of deep convection remains subject to large uncertainties associated with gaps in fundamental understanding. The complexity of coupled microphysical and dynamical processes and the difficulty of obtaining adequate in situ observations present substantial barriers to progress. Polarimetric weather radar observations have been shown to provide considerable information relevant to deep convection microphysics, but have thus far seldom been used to characterize the lifecycle of individual cells. Here we use polarimetric radar observations from the Houston NEXRAD radar to identify and track isolated convective cells under conditions where they are relatively susceptible to the influence of local pollution sources, providing a natural laboratory for observing updraft polarimetric signatures under varying aerosol conditions and relatively uniform thermodynamic conditions. We correlate lighting flash rates with polarimetric radar signatures for a limited number of cases to investigate features such as K_DP columns, Z_DR columns, and radar-estimated rain rate and raindrop size distribution properties. Results include a preliminary climatology of polarimetric radar signatures in tracked isolated updrafts over four years during summer-season onshore flow conditions. Sensitivity of results to updraft identification and cell tracking methodologies is briefly assessed.