Verification of RASS-measured temperature profiles using a radio-controlled model glider

Abstract

Potential sonic temperature profiles from a continuous electromagnetic, pulsed acoustic, radio acoustic sounding system (RASS) were compared with profiles recorded by a commercially available temperature, relative humidity and pressure recorder mounted in a radio-controlled model motor-glider. The glider profiles covered the period of the morning transition in the lowest 200 m of an initially stably stratified boundary layer. Comparison of the profiles shows that the sonic temperature can be calculated based on the average speed of sound in the boundary layer; this removes the need to correct for vertical velocity in each temperature profile, thus avoiding the possibility of contaminating the temperatures with measurement noise from the vertical velocity profiles. Further, the low-level cold bias that occurs with the spatially separated transmit and receive antennas of a bistatic RASS system was not significant for the present measurements as the separation between the antennas was minimised. The comparison of RASS and glider temperatures gives confidence in the use of RASS-derived temperatures for investigating the performance of boundary layer models.