Experimental Determination of Temperature Profiles by Ground-Based Microwave Radiometry

Abstract

A one-week experiment was conducted to evaluate a dual-frequency microwave radiometer for recovering low altitude temperature profiles; the two-channel radiometer operated at 53.5 and 54.5 GHz. Meteorological support included radiosondes, helicopters, and an instrumented 150 m tower. Statistical inversion of 13 radiometer angular scan data sets resulted in an average rms error of 2.0 K up to 3 km for the microwave system. Significant features of thermal inversion structure were recovered. A continuous set of fixed-angle brightness observations correlated well with temperatures measured on the tower. The statistical inversion method and the Backus-Gilbert method were applied to the analysis of the accuracy and the spatial resolution of the ground-based system. Model calculations were performed to estimate the effects of departures from horizontal stratification and of significant time variation in temperature structure during an elevation scan.