IMPROVED RADIO ACOUSTIC SOUNDING TECHNIQUES

Improved radio acoustic sounding system (RASS) technology for use with radar wind profilers has been developed and applied to 915-MHz and 50 -MHz profilers. The most important advance is the simultaneous measure ment of the wind velocity to correct the acoustic velocity measurement for air motion. This eliminates the primary source of error in previo us RASS measurements, especially on short time scales. Another improve ment is the use of an acoustic source that is controlled by the same c omputer that controls the radar. The source can be programmed to produ ce either a swept frequency or a random hopped frequency signal. Optim um choices of the acoustic source parameters are explored for particul ar applications. Simultaneous measurement of acoustic and wind velocit y enables the calculation of heat flux by eddy correlation. Preliminar y heat flux measurements are presented and discussed. Results of the u se of RASS with oblique beams are also reported.