微波辐射计反演大气温湿度廓线与降水相关性分析

Correlation analysis of atmospheric temperature and humidity profiles retrieved from microwave radiometer with precipitation

利用辽宁省阜新蒙古族自治县QFW-6000型地基微波辐射计和邻近探空资料,对微波辐射计反演精度进行评估,分析云中积分液态水含量、积分水汽含量与降水量的变化特征。结果表明:微波辐射计的反演参量与探空资料具有高相关性,反演的相对湿度基本大于探空测量的相对湿度,近地面与高层的误差在5%以内。基于云中积分液态水含量与降水量的统计分析发现,降水开始前存在明显跃增,云中积分液态水含量会快速增大到1 mm以上,随着降水的持续,云中积分液态水含量一直维持在2 mm以上,当降水结束,云中积分液态水含量迅速回落至0.2 mm以下。积分液态水和积分水汽含量为雨天>云天>晴天,积分水汽含量在不同天气下具有相似的垂直结构,均表现出随高度升高递减的变化趋势,水汽在高空的递减速率相对较慢,到近地层递减速率明显加快;云中积分液态水含量在云天和晴天的垂直分布结构相似,最大值分别为0.15 g·m-3和0.10 g·m-3,均位于1 km高度处;雨天云中积分液态水含量具有两个峰值区间,分别位于1.0 km和2.5 km高度处。云中积分液态水含量和积分水汽含量呈现白天高值而夜间及清晨低值的日变化特征,云底高度则呈相反的变化趋势。

By using the QFW-6000 ground-based microwave radiometer in Fuxin Mongolian autonomous county in Liaoning province and its nearby sounding data,the retrieval accuracy of the microwave radiometer was evaluated,and the changing characteristics of the integrated cloud liquid water content(IIW),the integrated total water vapor content(TWV)and precipitation were analyzed.The results show that the inversion parameters of the microwave radiometer are significantly correlated with those of the sounding data.The retrieved relative humidity is generally greater than that of the sounding data,and the inversion errors of relative humidity in the near ground and the upper layer are both within 5%.Based on the statistical analysis of the IIW and precipitation,it is found that the IIW increases steeply and rapidly to more than 1 mm before the start of precipitation and remains above 2 mm as the precipitation continues,then quickly drops back below 0.2 mm with the end of the precipitation.The IIW and TWV in turn decrease in order of rainy days,cloudy days,and clear sky.Meanwhile,the TWV has a similar vertical structure under different weathers,and all show a decreasing trend with height increasing.In addition,the lapse rate of water vapor content is relatively smaller at a high altitude and larger in the near-surface layer.Besides,the vertical distribution structures of the IIW in the cloudy sky and the clear sky are similar with the maximum values of 0.15 g·m-3 and 0.10 g·m-3 at a height of 1.0 km,respectively.Whereas,the IIW on rainy days has two peak intervals respectively located at the heights of 1.0 km and 2.5 km.In the meanwhile,the IIW and TWV show the daily change characteristics with high values in the daytime and low values at night and in the early morning,while the cloud base heights show the opposite trends.