Radar-derived thermodynamic fields in severe storms from in-situ data and Lagrangian objective analysis

Mobile radars and in-situ sensors play crucial roles in the analysis of dynamical processes governing the development and evolution of low-level mesocyclones, tornadoes, and other kinematic features of severe convective storms. This paper reports the application of a new Lagrangian objective analysis technique to derive thermodynamic fields employing in-situ data and high-resolution, time-spaced 3-D multi-Doppler radar wind analyses in storms and their inflow boundary layers. Propagating in-situ observations along radar-derived airflow trajectories with microphysical forcing of heat and humidity, cloud volumes are derived from gridded output fields of water vapor content, virtual potential temperature, and saturation point. The derived thermodynamic fields could in turn be used to evaluate baroclinic vorticity generation mechanisms with possible importance for tornadogenesis.

To assist in evaluating in-situ sampling strategies proposed for VORTEX2, the Lagrangian analysis technique is applied to the tornadic 29 May 1994 storm complex observed during VORTEX. Available mobile mesonet, sounding, and research aircraft data are combined with various supplemental in-situ “pseudo-data” sources and airborne Doppler radar winds to explore impacts of proposed mobile sampling strategies on the derived low-level thermodynamic storm structure. Features of special interest include the precipitation- and pre-storm boundary layers, the forward flank and wrapping gust frontal baroclinic zones, the main updraft and rear flank downdraft, the low-level mesocyclone, and the wall cloud. Preliminary analysis results will be reported at the conference.