149 Convective Core Vertical Velocity Properties and Relationship with Hydrometeors in Mid-latitude Continental Mesoscale Convective Systems

Tuesday, 29 August 2017
Zurich (Swissotel Chicago)
Zhe Feng, PNNL, Richland, WA; and S. Giangrande and J. C. Hardin

Understanding of the interaction between convective updraft dynamics and the feedback associated with cloud microphysical processes are becoming increasingly important as convection-permitting modeling are becoming possible in regional climate modeling. The explicit representation of convective processes in high-resolution models makes direct evaluation of convective behaviors against observations of core properties possible. Recent studies show large errors exist in cloud-system resolving models in simulating the intensity of convective updrafts in organized convection as compared to available vertical air velocity from radar-based observations, in part owing to uncertainties in model microphysical parameterizations. However, direct measurements of convective vertical air velocities in particular are limited, usually derived from a handful of field campaign aircraft convection penetrating flights, or estimated from multi-Doppler radar-based retrievals.

In this work, we make use of warm-season observations of vertical velocity retrievals from four radar wind profilers (RWP) operated by the Department of Energy Atmospheric Radiation Measurement (ARM) program at the Southern Great Plains facility to examine the properties of convective updraft and downdraft cores associated a database of mesoscale convective systems (MCSs) that passed over northern Oklahoma from 2011-2016. To provide necessary context, these MCSs were identified and tracked with the nearby KVNX NEXRAD (~60 km away), aiding in characterizing convective core lifetime, life cycle stage, propagation speed, as well as proxy core microphysical insights from dual-polarization measurements as these MCSs pass over the RWPs. We quantify the updraft/downdraft core properties including core sizes, vertical velocities, mass fluxes as functions of life cycle stages, and investigate the relationship between hydrometeor profiles observed by NEXRAD and convective core dynamics observed by RWPs.

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