Boundary layer height and entrainment zone thickness measured by lidars and wind-profiling radars

The authors examine measurements of boundary layer height z(i) and entrainm ent zone thickness observed with two lidars and with a radar wind profiler during the Flatland96 Lidars in Flat Terrain experiment. Lidar backscatter is proportional to aerosol content land some molecular scatter) in the boun dary layer, and wind profiler backscatter depends on the refractive index s tructure (moisture gradients and turbulence strength). Although these backs catter mechanisms are very different, good agreement is found in measuremen ts of z(i) at 1-h resolution. When the dataset is limited to daytime convec tive conditions (times between 1000 and 1700 LT), correlation coefficients between the profiler and each lidar are 0.87 and 0.95. Correlation between the two lidars is 0.99. Comparisons of entrainment zone thickness show less agreement, with correlation coefficients of about 0.6 between the profiler and lidars and 0.8 between the two lidars. The lidar measurements of z(i) make use of coefficients of a Haar continuous wavelet transform of the back scatter profile. The wind profiler measurements use a standard technique. T he wavelet transform technique is shown to provide consistent results with lidar data at 1-s time resolution.