Evolution of Monthly Mean Convective Boundary layer Depths Detected from WSR-88D Observations

Dual-polarization WSR-88D radars can be used to estimate the depth of the convective boundary layer (CBL) from quasi-vertical profiles of differential reflectivity (Z_DR), as Bragg scatterers lead to a local minimum in the vertical profile of Z_DR at the top of the CBL (see Figure). An automated technique is developed to track the vertical minimum of Z_DR throughout the daytime hours and applied to observations from 50 WSR-88D radars across CONUS. These sub-hourly estimates of CBL depth are averaged for each month of the year for each of the 50 radars, creating a monthly mean CBL evolution on 30 min time scales. The CBL evolution from various locations across CONUS are compared, allowing one to assess how the CBL evolves in different climate zones and for different years. The capability of the dual-polarization WSR-88D radars to provide enhanced CBL information opens up new boundary layer research frontiers.