华西秋雨逐日监测指数的建立及其分析

Establishment and Analysis of the Daily Monitoring Index for Huaxi Autumn Rain

使用1972—2011年气象站逐日降水量和日照时数资料,建立了新的华西秋雨逐日监测指数,并对新指数的空间、时间适用性进行分析,进而研究华西秋雨的季节内变化特征。利用实际气象灾害记录确定了华西秋雨区主要发生省份的秋雨偏强年,与新华西秋雨监测指数进行对比验证,发现大多数年份两者是一致的。另外也有不一致的情况,有的年份监测指数显示秋雨偏强,但是并不在灾害记录确定的偏强年里,通过进一步查找文献和对比实际降水资料,发现监测指数符合实际情况。还有一些通过灾害记录确定的偏强年,秋雨监测指数不强,进一步研究指出这些异常年份的秋雨灾害往往发生在较短的几天里,其余大部分时间内华西秋雨正常或偏弱,所以并没有在全年的监测指数中得以体现。气候平均状况下华西秋雨强度9—10月随时间在波动中减弱,包含3个偏强时段,其中9月6一16日为最强的一个时段。9—10月华西秋雨的季节内变化存在较大的年代际差异,其中20世纪70年代华西秋雨有2个显著时段(9月13—22日和10月4—8日),80年代华西秋雨有3个显著时段(9月3—17日、9月25至10月8日和10月13—25日),90年代华西秋雨有3个显著时段(9月12—22日、10月3—7日和12—20日),21世纪初有3个显著时段(9月1-10日、9月21至10月7日和10月11—16日)。个例应用表明,监测指数能直观清晰地表现出华西秋雨发生、发展和消失的整个演变过程。

Based on the daily precipitation and daily sunshine hour data from 1972 to 2011 at meteorological observation stations,a new monitoring index (Daily Autumn Rain Index,DARI)of Huaxi autumn rain is defined.The temporal-spatial applicability of DARI is analyzed and the intraseasonal variability is re-searched too.Based on the actual meteorological disaster records the strong years when more autumn rains occurred in the related provinces are indentified.Compared with the new monitoring index (DARI)it is found the DARI and the strong years are consistent in most cases.Of course,there exist some inconsisten-cies as well.In some years the monitoring indicators show the strong side,but there are no disaster re-cords.Some literatures and the actual rainfall data indicate that the monitoring index matches with the ac-tual situation.In some years there are disaster records,but little autumn monitoring index.Further re-search indicates that the disasters tend to occur only in a few days,in most of the remaining time it is nor-mal or weak,so there is no reflection in the year index.In climatic mean status,the intensity of Huaxi antumn rain weakens with fluctuation.The period from 6 to 16 September is the strongest period of the three.There is obvious interdecadal variation for the interseasonal variation of DARI.There are two sig-nificant periods in 1970s,three in 1980s,three in 1990s and three at the beginning of the 21st century. The application case shows that DARI can demonstrate the whole variation process of occurrence,develop-ment and disappearance of Huaxi autumn rain.