Estimates of Entrainment Zone Depth across the United States from Dual-Polarization WSR-88D Radar Observations

Recent work has shown that dual-polarization WSR-88D radars can be used to accurately estimate both convective boundary layer depth h and entrainment zone depth ∆h. We build on this work by developing an algorithm to estimate ∆h from WSR-88D data and apply it to a large dataset of WSR-88D observations for the calendar year 2022. Given the existence of a national network of WSR-88Ds, this produces the most spatiotemporally comprehensive dataset of ∆h to date. We find that there are regional and seasonal variations in ∆h with median values near 300 m in January and increasing to 600 m in summer. The values of ∆h are largest in the southeastern CONUS and smallest in the northwestern CONUS. Yearly mean ∆h/h is a maximum at 1000 local time, with values above 0.6, decreasing to;0.4 in the afternoon. We also evaluate and extend an existing ∆h parameterization based on lidar data and provide improved fits for days with large ∆h.