Radio acoustic sounding with a UHF volume imaging radar

An implementation of a radio acoustic sounding system (RASS) using a UHF volume imaging radar is presented. The volume-imaging ability of the radar permits the study the spatial structure of the RASS echo observing both the diffraction pattern on a receiving antenna array and the beamformed images of the RASS intensity. Fine space and time resolution RASS observations of a developing diurnal boundary layer are considered, where observed structures are consistent with theoretical predictions presented in the RASS literature. The RASS amplitude signature is highly variable in space and time, hindering the estimation of complete instantaneous fields of virtual temperature. However, it is possible to obtain spatial statistics. Structure functions computed explicitly show r^2/3 behavior typical of isotropic turbulence and vertical profiles of the structure function parameter show a z^-4/3 behavior, although they are significantly larger than expected based on surface measurements.