复杂山地环境下雷暴天气中的地基微波辐射计影响距离分析

ANALYSIS OF EFFECTIVE DETECTION DISTANCE OF GROUND-BASED MICROWAVE RADIOMETER IN THUNDERSTORM WEATHER IN COMPLEX MOUNTAINOUS TERRAINS

利用2017年2月—2018年10月地基微波辐射计和无线电探空仪、闪电和雷达数据,首先评估了微波辐射计温度和绝对湿度在不同高度的探测性能,微波辐射计和无线电探空仪不同高度的温度的相关系数为0.800~0.985,绝对湿度的相关系数为0.600~0.916;微波辐射计温度的标准差为3.9~6.1℃,绝对湿度的标准差为0~4 g/m³,无线电探空仪温度的标准差为4.2~6.1℃,绝对湿度的标准差为0.1~4.2 g/m³;微波辐射计和无线电探空仪温度绝对误差的标准差为1.06~2.90℃,绝对湿度绝对误差的标准差为0.08~2.02 g/m³。二者K指数相关系数为0.945。其次利用K指数上升和下降到35℃的时次和不同距离闪电开始和结束时次做相关性分析,结果表明在30 km处具有最大的相关系数(0.864),这可能就是微波辐射计温度和湿度在复杂山地下雷暴天气中能够代表的大气层结的有效距离。最后统计分析了微波辐射计K指数上升达35℃时,90%上游移向微波辐射计的雷暴回波(30 dBZ雷达回波超过-15℃高度层)距离微波辐射计平均距离为35.3 km,移到微波辐射计附近平均需要92.8分钟,局地雷暴(40 km以内)生成需要138.2分钟。

By using the data of ground-based microwave radiometer(MWR),radiosonde,lightning location system and radar from February 2017 to October 2018,we first evaluated temperature and absolute humidity detection performance of MWR at different altitude.It shows that the correlation coefficients of temperature between MWR and radiosonde are 0.800~0.985,and those of absolute humidity are 0.600~0.916;the standard deviations of temperature and absolute humidity of MWR are 3.9~6.1℃and 0~4 g/m³,and those of radiosonde are 4.2~6.1℃and 0.1~4.2 g/m³.Standard deviations of absolute error of temperature between MWR and radiosonde are 1.06~2.90℃,and those of absolute humidity are 0.08~2.02 g/m³.The correlation coefficients of K index between MWR and radiosonde is 0.945.Second,we evaluated the correlation coefficients of hours when K index derived from MWR rose and fell to 35℃and when thunderstorms began and ended at different distances.It shows that the maximum correlation coefficient(0.864)is found at areas 30 km from the MWR,which may be taken as the areas over which the temperature and humidity measured by MWR is considered to be representative of the atmospheric conditions.Finally,statistical analysis shows that 90%of the thunderstorm echoes moving upstream to the MWR are 35.3 km away from the radiometer when K index of MWR rises to 35℃.Thunderstorm echoes refer to those where 30 dBZ radar echoes exceed the-15℃level height.It takes 92.8 minutes on average for the thunderstorm echoes moving upstream to reach the vicinity of the MWR,and it takes 138.2 minutes for local thunderstorms within a range of 40 km to form.