山东暴雨天气学预报指标的统计特征分析

摘要

By using daily,hourly precipitation data of Shandong Province and NCEP FNL (Final)opera-tional global analysis data from 2000 to 2011,and based on the spatial and temporal statistics of physical indicators of rainstorms in Shandong Province,the physical indicators characteristics of rainstorms in dif-ferent seasons and regions were analyzed.The results show that rainstorms have obvious nighttime en-hanced trend.The physical indicators of rainstorms in daily operations have different levels of seasonal change.On one hand,the thresholds of these indicators have significant seasonal differences,for example, the specific humidity indicator is 10 g·kg-1 in April and May but it is only 14 g·kg-1 in July,and on the other hand,the effects of water vapor,dynamic and thermal instability factor on rainstorms are not the same in different seasons.The water vapor factor is usually high,and the dynamic and thermodynamic in-stability factors are low in summer.Furthermore,atmospheric convective instability can be stronger but baroclinicity gets weakened in summer.However it is contrary to the other seasons.Regional difference of the physical indicators of Shandong rainstorms is not the same as seasonal variations,but it is different among various factors.The rainstorms in the south of Shandong need stronger water vapor,and the ther-mal instability is also higher,the Kindex is about 0 .5℃ higher than other areas while the rainstorms of east part of Shandong Peninsula have higher dynamic factors.Meanwhile,a wide range rainstorms and n regional rainstorm need better moisture conditions,stronger dynamic conditions,but lower convective in-stability conditions .%提采用山东省2000-2011年逐日、逐时降水资料和NCEP最终分析资料，研究了山东省暴雨天气学指标物理量的时空分布，获得了不同季节、区域和范围的暴雨预报指标特征。研究表明：山东暴雨有明显的夜间增强趋势。业务中常用的暴雨指标物理量均有不同程度的季节性变化特征，一方面表现在指标物理量的阈值有明显的季节性差异，例如暴雨的850 hPa比湿指标在4、5月仅为10 g·kg-1，而7月则可达14 g·kg-1；另一方面不同季节的水汽、动力和热力不稳定等因子对暴雨贡献也不尽相同，通常盛夏季节暴雨的水汽因子较高，而动力因子偏低，而且对流不稳定性较强，但斜压性减弱，其他季节的暴雨则相反。山东暴雨指标物理量的区域性差异没有季节性差异明显，同时各因子的区域差异也并不一致，具体来说鲁南暴雨需要更强的水汽，同时热力不稳定性因子也较高，K指数比其他区域约高0．5℃，而半岛地区暴雨动力因子更强。同时，大范围暴雨和区域暴雨需要更好的水汽条件、更强的动力条件，但对流不稳定条件较低，而局地暴雨则与此相反。