基于微波辐射计RPG-HATPRO的夏季午后强对流个例分析

A Severe Convection Analysis in Summer Afternoon Based on RPG-HATPRO

利用NCEP再分析资料、余姚自动气象站观测数据以及RGP-HATPRO型微波辐射计资料,对2017年7月14日傍晚到夜里发生在余姚的一次强对流天气过程进行综合分析。结果表明,该次强对流过程是副高边缘发生的准正压类的强对流过程,大气层结无明显“上干下湿”结果,不利于冰雹发生,而较高的K指数、CAPE值则非常利于短时强降水、雷暴大风的出现,与实况较为吻合。强对流天气过程发生前通过微波辐射计得出的综合水汽含量维持在52 kg/m2以上、K指数高达40℃、CAPE值达2000 J/kg以上,抬升指数低至−10,与通过探空数据得到的强对流触发阈相对,K指数和CAPE值要高的多,而抬升指数则小的多,通过进一步统计多个对流过程得到基于微波辐射计对流指数的经验阈值,对日常预报将有显著的促进作用。

Based on NCEP reanalysis data, Yuyao automatic weather station observation data and RPG-HATPRO microwave radiometer data, a severe convective weather process occurred in Yuyao from the evening to the night of July 14, 2017 was comprehensively analyzed. The results show that the strong convective process is a quasi barotropic strong convective process at the edge of the sub-tropical high. There is no obvious “upper dry and lower wet” result in the atmospheric stratification, which is not conducive to the occurrence of hail. The higher K index and Cape value are very conducive to the occurrence of short-term heavy rainfall and thunderstorm gale, which is in good agreement with the actual situation. Before the occurrence of severe convective weather, the comprehensive water vapor content obtained by microwave radiometer is above 52 kg/m2, K index is as high as 40˚C, CAPE is up to 2000 and Lifted Index is even as low as −10. Compared with the strong convection trigger threshold obtained by artificial sounding data, the K-index and CAPE are much higher, while the Lifted Index is much smaller. The empirical threshold based on the convection index of microwave radiometer is obtained by further statistical analysis of multiple convection processes, which will significantly promote the daily forecast.