Proper frequencies of a down-looking water-vapor radiometer over sea surface

摘要

Altimeter observation on board an Earth-orbiting satellite over sea surface is corrupted by the water vapor path delay. Such error can be calibrated for by a down-looking microwave radiometer. The effects of water vapor profile, sea surface temperature, wind speed and brightness temperature measurment error on the calibration precision were studied. Proper frequency combinations were also searched to minimize these effects. The analysis indicates that it is possible to achieve a subcentimeter estimate of water vapor path delay on nadir observation with an on-board microwave radiometer.