近48a鄂东汛期暴雨日数的时空变化特征

Spatial and Temporal Distribution of Flood-season Rainstorm Days Over Eastern Hubei in the Last 48 Years

使用鄂东地区5市24站1961—2008年逐日降水资料,采用合成法、线性趋势、滑动平均、Morlet小波分析以及M-K突变检验等方法,分析近48 a鄂东汛期暴雨日数的气候特征和年际、年代际变化规律及其周期变化,并对该地区近48 a不同时间段暴雨日数进行突变检验。结果表明:1)与20世纪90年代前30年相比,90年代后18年,鄂东6月下旬暴雨减少,7月中、上旬暴雨增多,与该地区近些年来梅雨开始和结束时间均推迟的变化趋势一致;2)20世纪90年代以后,暴雨高发中心出现鄂东北向西扩展、鄂东南向南偏移的态势;3)近48 a,鄂东汛期、主汛期和梅雨期暴雨日数变化存在准4 a和准6 a周期;4)鄂东汛期、主汛期和梅雨期暴雨日数均先突变增加、后突变减少,即20世纪70年代中前期开始突变增加,到21世纪头10年中后期开始突变减少。

The resultant method,linear tendency,overlapping average,Morlet wavelet and M-K catastrophe test were used to analyze the climate characteristics,rules of interannual and interdecadal changes and periodic change of the flood-season rainstorm days over the Eastern Hubei in the last 48 years,and abrupt change test on the rainstorm days in different periods of time were made with the daily precipitation data from 24 stations in the Eastern Hubei form 1961 to 2008.The results indicate the following.1） Compared with early thirty years in 1990s,the number of the Eastern Hubei rainstorm days was decreasing in late June and increasing in early and mid-July in the later eighteen years in 1990s,which is consistent with the change trend of both the initial and end time of Meiyu delaying in recent years in the same region.2） The high frequency center of rainstorm over the Eastern Hubei expands to westward from northeast and migrates southward from the southeast after 1990s.3） In the last 48 years,there are quasi-period of 4 years and quasi-period of 6 years in the number change of rainstorm days in the flood season,the main flood season and the Meiyu period.4） The number of the Eastern Hubei rainstorm days in the flood season,the main flood season and the Meiyu period increased abruptly in the early mid-1970s,and decreased abruptly in the beginning of 21st century.