Impact of precipitation on the retrieval deviation of ground-based microwave radiometer

Impact of precipitation on the retrieval deviation of ground-based microwave radiometer is analyzed using high temporal resolution (3 h) and high spatial vertical resolution (30 m) radiosonde data and MP-3000A microwave radiometer data of Wuhan station. The result of the compared profiles shows that the precipitation has no obvious affect on the profiles of temperature and vapor density between these two devices. But the correlation of relative humidity between radiosonde data and microwave radiometer data is affected by precipitation obviously,and the correlation is better in precipitating condition. Overall, the system deviations between the radiosonde profile and microwave radiometer profile are bigger in precipitating condition. The mean deviations of temperature, relative humidity and water vapor density profile of microwave radiometer are 1.0-2.5 ℃, 6%-15%, 0.08-1.75 g·m-3 respectively, and the corresponding mean square deviations are 1.3-1.6 ℃,14%-17%, and 1.28-1.85 g·m-3 respectively. The comparison between the microwave radiometer data and radiosonde data by point-to-point at different heights and at the same time shows that precipitation affects seriously the positive correlation between the two kinds of the data mentioned above resulting in the negative correlation at most of heights and increasing the mean deviation and mean square deviation of temperature and vapor density.