Exploring Convective Boundary Layer Depth and Entrainment Zone Properties with Dual-Polarization Radar Observations

Convective boundary layer (CBL) characteristics, especially depth, play an important role in many atmospheric processes. However, frequent observations of CBL depth and other CBL characteristics are not routinely available from current operational observation systems. Recent work has taken advantage of the existing network of dual-polarization WSR-88D radars to investigate CBL depth estimates that can be produced for every radar volume scan (roughly every 10 minutes or less) at every WSR-88D site. This study further examines these observations to retrieve more information on the structure of CBLs with a focus on entrainment zone (EZ) depth.

Utilizing differential reflectivity (Z_DR) data from the WSR-88D radar in State College, Pennsylvania (KCCX), CBL depth and EZ properties are investigated across 40 days starting in summer 2022. These signals are compared to atmospheric observations collected by Windsond weather balloons launched from The Pennsylvania State University, University Park campus. Results confirm that the center of the low-Z_DR channel found in quasi-vertical profiles (QVPs) during the daytime correlates well with Windsond-observed CBL depths, while the vertical extent of the channel serves well as a proxy for EZ depth. Additionally, it is found that QVPs of azimuthal variance of Z_DR can provide further information on CBL and EZ characteristics, especially when the Z_DR signal alone is unclear. Observed EZ depths also will be compared with current EZ depth parameterizations.