TOPEX Microwave Radiometer in-flight performance evaluation

Results of the verification campaign for the TOPEX Microwave Radiometer are presented. Pre-flight calibration and path delay retrieval algorithms resulted in 6-12 K offsets in brightness temperature and a 10% relative error in the path delay, relative to coincident radiosondes. The offsets were removed by correcting processing errors found in the thermal/vacuum test data analysis. The relative error was removed by correcting estimates of the far sidelobe level of the TMR antenna pattern and by decreasing the value assumed for the water vapor line strength at 22.235 GHz. TMR path delay retrieval accuracy is estimated at 1.0-1.8 cm RMS under clear, cloudy, and windy conditions