雅砻江流域降雨天气特征及致洪暴雨预报

Rainfall characteristics and flooding rainstorm forecast of Yalong River Basin

采用统计学、天气学等方法分析了2005～2010年5～10月雅砻江流域水文站、气象站日雨量资料及气象要素资料。通过对期间217次降雨过程中雨带强度和位置变化特征的统计分析发现,影响雅砻江流域的过程性雨带有5种类型,其中以南压型雨带的发生率最高,降雨强度最大,对水情的影响程度最高。分析了影响雅砻江流域过程性降雨的天气系统以及其活动规律。从日常业务预报的角度,筛选出89个对应的致洪强降雨样本个例,分析提出致洪强降雨预报的天气学判据,即在强降雨发生前24 h,强降雨区附近有低值系统活动,且流层中低层天气要素呈现增温、增湿、气压降低等现象。

The daily rainfall data and factors of hydrological and meteorological stations in the Yalong River Basin between May and October from 2005 to 2010 were analyzed by using the methods of statistics and meteorology. After statistical analysis on the characteristics of intensity and location variation of rain belts in 217 rainfall processes during this period, it is found that there are 5 types of rain belts, in particular, the southerly moving type occurs most frequently with the highest rainfall intensity and influ- ence on the water regime. The weather systems and their activity regularity that lead to the rainfall process are analyzed as well. 89 heavy flooding rainfall records are selected from the view of routine flood forecasting practice, so as to analyze and propose the meteorological criterion for flooding rainstorm. The results show that, 24 hours before the occurrence of an intensive rainfall, low - value system is active near intensive air rainfall areas, and the synoptic factors in middle - low troposphere has the trend of temperature and humidly increasing, and air pressure reducing.