On Polarimetric Radar Signatures of Deep Convection for Model Evaluation: Columns of Specific Differential Phase Observed during MC3E*

Abstract

The representation of deep convection in general circulation models is in part informed by cloud-resolving models (CRMs) that function at higher spatial and temporal resolution; however, recent studies have shown that CRMs often fail at capturing the details of deep convection updrafts. With the goal of providing constraint on CRM simulation of deep convection updrafts, ground-based remote-sensing observations are analyzed and statistically correlated for four deep convection events observed during the Midlatitude Continental Convective Clouds Experiment (MC3E). Since positive values of specific differential phase (<i>K</i>_DP) observed above the melting level are associated with deep convection updraft cells, so-called "<i>K</i>_DP columns" are analyzed using two scanning polarimetric radars in Oklahoma: the National Weather Service Vance WSR-88D (KVNX) and the Department of Energy C-band Scanning Atmospheric Radiation Measurement (ARM) Precipitation Radar (C-SAPR). KVNX and C-SAPR <i>K</i>_DP volumes and columns are then statistically correlated with vertical winds retrieved via multi-Doppler wind analysis, lightning flash activity derived from the Oklahoma Lightning Mapping Array, and KVNX differential reflectivity (<i>Z</i>_DR). Results indicate strong correlations of <i>K</i>_DP volume above the melting level with updraft mass flux, lightning flash activity, and intense rainfall. Analysis of <i>K</i>_DP columns reveals signatures of changing updraft properties from one storm event to another as well as during event evolution. Comparison of <i>Z</i>_DR to <i>K</i>_DP shows commonalities in information content of each, as well as potential problems with <i>Z</i>_DR associated with observational artifacts.