重庆不同天气条件下地基微波辐射计探测特征

利用2012年1月至2014年8月重庆沙坪坝站的微波辐射计和探空数据,通过数值模拟检验微波辐射计的亮温精度,并统计分析晴空、有云和降水天气条件下微波辐射计反演产品的变化特征。结果表明:(1)有云时微波辐射计氧气通道53.85、54.00 GHz亮温与探空观测温度相关性较好;晴空和有云时MonoRTM模拟亮温与微波辐射计观测亮温相关性较好。(2)不同天气条件下,微波辐射计反演温度与探空观测值的相关性都较高,降水时4.0 km以下微波辐射计反演温度明显偏高,有云和晴空时3.8 km以下的温度平均绝对误差小于2℃。微波辐射计反演的相对湿度与探空观测值的相关性较同高度层温度的相关性差,有云时1.0~2.6 km高度反演的相对湿度平均误差很小,降水时4.5 km以下平均误差也较小且稳定。降水时4.0 km以下微波辐射计反演的水汽密度平均误差明显偏大,有云时多数高度层平均误差较小。(3)4.2 km以下降水时08:00微波辐射计反演温度的平均误差较大,有云时08:00微波辐射计反演温度和水汽密度的平均误差均较小。说明微波辐射计反演的大气廓线具有可用性,且在稳定大气环境中反演效果更好。

Characteristics of ground-based microwave radiometer profiles under different weather conditions in Chongqing

Based on the data of microwave radiometer and radiosonde at Shapingba station in Chongqing from January 2012 to August 2014, the brightness temperature accuracy of microwave radiometer was verified by numerical simulation, and the variation characteristics of microwave radiometer retrieved products on sunny, cloudy and precipitation days were analyzed statistically. The results are as follows:(1) There was a high correlation between the brightness temperature at oxygen channel 53.85, 54.00 GHz and the temperature of radiosonde values on cloudy days, and there was also a high correlation between the simulated brightness temperature of MonoRTM model and the observed brightness temperature of microwave radiometer on sunny and cloudy days.(2) Under different weather conditions, the correlation between the temperature retrieved by microwave radiometer and radiosonde values was high. The temperature retrieved by microwave radiometer was obviously higher below 4.0 km on precipitation days, and the average absolute error below 3.8 km was less than 2 ℃ on sunny and cloudy days. The correlation between relative humidity retrieved by microwave radiometer and radiosonde values was worse than that of temperature at the same altitude. The average error of retrieved relative humidity was small at the height of 1.0-2.6 km on cloudy days, and it was also small and stable below 4.5 km on precipitation days. The average error of water vapor density retrieved by microwave radiometer was obviously larger below 4.0 km on precipitation days, while the average error on most altitude layers was smaller on cloudy days.(3) The average error of temperature retrieved by microwave radiometer below 4.2 km was large at 08:00 BST on precipitation days, but the average error of temperature and water vapor density retrieved by microwave radiometer was small on cloudy days. It showed that atmospheric profiles retrieved by microwave radiometer were available, and the inversion effect was better in stable atmospheric environment.