Combined lidar and in-situ measurements of waves in the stable night-time boundary layer above Kansas

Measurements during the CASES99 (Co-operative Atmospheric Surface Exchange Study) field campaign near Wichita, Kansas in October 1999 often showed monochromatic gravity waves, sometimes breaking, in the night-time boundary layer. We combine range-height cross sections of wind velocity measured by HRDL (High Resolution Doppler Lidar), and in-situ measurements of both the mean values and turbulent fluctuations of temperature and velocity by TLS (Tethered Lifting System). The TLS in-situ measurements, although one-dimensional only, resolve vertical scales smaller than possible by lidars or radars. This includes fine-scale structure of the breaking waves, and the distribution of wind shear and turbulence. The combined measurements are used to investigate the mixing efficiency of the waves, in relation to the usual assumption that vertical mixing is small in stable conditions over gentle terrain.