茂名市暴雨的气候特征

Climatic Characteristics of Heavy Rains in Maoming City

利用茂名5个气象观测站1972—2015年的暴雨资料,研究了茂名市暴雨日数的变化特征,及汛期暴雨趋势、突变和周期特征。结果表明:(1)茂名各站的年暴雨日数是有差异的,总体呈从西南向东北减少的特征,最多出现在茂名西南部的化州,最少出现在茂名东南部的电白和北部的信宜;前汛期暴雨日数从北到南逐渐减少;后汛期暴雨日数分布与前汛期恰好相反,是从北到南逐渐增加。(2)茂名各站多年平均的月暴雨贡献率呈双峰型分布,主峰位于6月,次峰位于8月。(3)汛期暴雨降水量和暴雨频次都呈微升趋势,通过α=0.05的显著性检验,且在近44年的气候变化过程中存在着突变性。(4)通过滑动T检验,检测出汛期暴雨降水量和暴雨频次在近44年来出现过一次明显的突变,突变年是2007年。(5)小波分析表明,茂名汛期暴雨降水量存在明显的12~13、7~9和4年左右的年际、年代际周期震荡,以7~9和4年左右的主周期震荡为主,这2个主周期都表明在2015年后的未来几年茂名汛期暴雨降水量处于减少期。

Using the data of heavy rains from five of the meteorological observation stations in Maoming for 1972 -2015, this work studies the variation characteristics of the number of heavy-rain days as well as the characteristics of the trends, abrupt changes and periodic variation of flood-season heavy rains. The re- sults are shown as follows. （ 1 ） The annual number of heavy-rain days vary among the stations of Maoming, showing a general trend of decreasing from the southwest to the northeast, with the largest in Huazhou, in the southwest of the city, and the smallest in Dianbai, in the southeast, and Xinyi, in the north. For the annu- ally first flood season, the number of heavy-rain days decreases gradually from the north to the south, and for the annually second flood season, it distributes just the opposite, increasing from the north to the south. （2） The monthly contribution rate of heavy rains, averaged over multiple years for these stations of Maoming, is of bimodal distribution, with the primary peak in June and the secondary peak in August. （3） For heavy rains, both the flood-season rainfall amount and the frequency tend to increase slightly and pass the signifi- cance test at ot = 0. 05, with abrupt changes in the climate over the 44 years. （4） By the running T-test, the flood-season rainfall amount and the frequency are found to have experienced an obvious abrupt change in 2007. （5） As shown in the wavelet analysis, the flood-season rainfall amount is obviously marked by intera- nnual and interdecadal periodic oscillations of 12 - 13, 7 -9 and about 4 years, with the latter two being the primary oscillations. These two periods indicate that the flood-season rainfall amount was in a decreasing stage in the years after 2015.