利用探空资料确定呼和浩特地区3类强对流天气预警阈值

Using Radiosonde Data to Determine Warning Thresholds of Three Types of Strong Convective Weather in Hohhot Area

利用呼和浩特探空站计算的16个物理量,分析了2012—2016年6—8月呼和浩特地区的冰雹、雷暴大风及短时强降水天气过程中各物理量差异,结果表明:①订正后的(对流有效位能)CAPE大于等于1000J·kg-1、0℃层高度约4200m左右,-20℃层约在7200m左右,500hPa和850hPa温差达-25℃,逆温层高度在2km以上基本可以判定为冰雹天气;②短时强降水对水汽的依赖度更高,且具有更强的热力不稳定性,低层的温度露点差、500hPa与850hPa的假相当位温差Δθse(500-850)、大气可降水量PW也是短时强降水天气的重要判据;③订正后的(下沿对流有效位能)DCAPE值雷暴大风明显大于冰雹和短时强降水,约为其他2类强对流天气的2倍,订正后的CAPE略小于其他2类强对流天气。根据四分位数法、所占比例≥70%以及均值法界定各类预报因子阈值大小,进而确立了呼和浩特地区强对流天气预警指标。经检验均值法确定的阈值指标命中率均达到50%以上,可参考价值较高。

In this paper,based on the 16 physical quantities calculated by the Hohhot radiosonde station,the differences in physical quantities between the hail,thunderstorm gale and short-term heavy precipitation in Hohhot from June to August 2012 to 2016 are analyzed.The results show that:(1)If the revised CAPE is greater than or equal to 1000 J·kg-1,the 0℃layer height is about 4200 mand the-20℃layer height around 7200 m,the temperature differences at 500 hPa and 850 hPa up to-25℃,and the height of the atmospheric temperature inversion layer is above 2 km.It can be basically determined that hail weather will occur.(2)Short-term heavy precipitation depends more on the water vapor and has stronger thermal instability.The lower-level difference between temperature and dew point,Δθse(500-850)and Precipitable Water Vapor(PWV)are also important criterions for short-term heavy precipitation weather.(3)The early warning indexes of strong convective weather in Hohhot can be established as:The revised DCAPE of a thunderstorm gale is significantly larger than that of hail and short-term heavy precipitation weather,which is about twice as large as the other two types of weather,while the revised CAPE is slightly smaller.Finally,the threshold sizes of all kinds of forecast factors can be defined by means of the quartile division method,the method of≥70%proportion(the proportion of severe convective weather samples is more than 70%)and the mean threshold method.The statistical test indicates that the hit rate of the threshold index determined by the mean method,up to more than 50%,is of higher reference value.