Determination of turbulent parameters in the atmospheric boundary layer with an UHF wind profiler. Comparison with in situ measurements

UHF wind profiler has proved to be a very useful tool for the investigation of the convective Atmospheric Boundary Layer (ABL) with a very good temporal and vertical resolution. Previous studies have demonstrated its ability to retrieve wind velocity field and mixing height. UHF Doppler spectral width contains another important information about the structure of the ABL related to the dynamic turbulent mixing. This information leads to the determination of the turbulent kinetic energy dissipation rate (Jacoby et al., 2002). When equipped with RASS, making use of the interaction between radio and acoustic wave, a UHF-RASS system can provide vertical profiles of the air virtual temperature. The spectral width of the “acoustic echo” contains also an important information on turbulent thermal fluxes. First, we investigate one method to evaluate momentum fluxes based on four beams measurements. They are deduced from the combination of wind velocity spectral width measurements obtained by two opposite beams. This estimation is made into the boundary layer during windy and convective conditions. Second, we propose two methods to evaluate the vertical virtual sensible heat flux using the height of the boundary layer, the temperature, the spectral width of the vertical velocity and of the “acoustic echo” deduced from UHF-RASS profiler. The first one is based on turbulent kinetic equation and the second on the heat equation ; both methods are conducted assuming horizontal homogeneous conditions without strong advection. In situ measurements obtained from tall masts and aircraft flights during two field campaigns are used to validate the results attached to these different remote sensing techniques.