近45年华中地区不同级别强降水事件变化趋势

The Variation Tendency of Heavy Precipitation Events in Different Grades During Recent 45 Years over Central China

  • 摘要: 利用华中五省84个测站1961—2005年逐日降水资料,通过分位值法、趋势系数法、蒙特卡洛统计检验法、曼肯德尔法、小波分析等现代统计诊断方法,分析了华中地区不同级别强降水的时空变化趋势、突变和周期特征。结果表明:随着分位值减小,降水量、日数的平均值和均方差逐渐减小,变差系数逐渐增大;而强度的3项指标均逐渐增大;在空间分布上,降水量自河南向湖南和江西逐渐增大;日数自北向南逐渐增大;强度以湖北东部至江西北部的长江中下游一线以及湖南西北部局部地区为高值区;区域平均的降水量、日数和强度均呈增加趋势,但不同测站表现不同;降水量一致在1993年发生突变,呈增多趋势;日数在20世纪80年代末、90年代初发生突变;强度自1994年开始增强,21世纪后加强、减弱现象交替出现;降水量、日数和强度有12~14年的年代际变化和6~9年的短期变化。

     

    Abstract: In the context of global climate change, frequencies and intensities of various extreme climate events are also changing. Central China is located at mid lower reaches of the Yangtze River, where rainstorm flooding disaster caused by heavy precipitation almost occurs every year. So it is extremely necessary to research variation characteristics of heavy precipitation events in Central China, which has important effects on improving the forecast of heavy precipitation and reducing the loss in this area. The interdecadal spatial temporal change trend, break and periods characteristics of all grade heavy precipitation events are studied using daily raingauge data of 84 weather stations from 1961 to 2005. These data are analyzed in terms of several modern statistical test methods such as percentile, trend coefficient, Monte Carlo statistical test, Mann Kendall break detector, Morlet wavelet transform etc.The results show that thresholds of heavy precipitation for 10%, 8%, 5% and 2% percentile is 24.7 mm, 28.6 mm, 37.6 mm and 57.8 mm by area averaged, respectively. The mean and standard deviation of heavy precipitation and raining days decrease with the percentile, variation coefficients of those increasements; while the mean, standard deviation and variation coefficient of intensity all rise gradually. As for spatial distribution, the heavy precipitation rises from Henan to Hunan and Jiangxi, the raining days rise from north to south. The intensity is lower in western Henan, northwestern Hubei, some parts of southern Hunan, and higher in the mid lower reaches of the Yangtze River, from eastern Hubei to northern Jiangxi, and some parts of northwestern Hunan. For a fixed grade, the heavy precipitation shows stronger linear trend than raining days, and linear trend of intensity is the weakest. The total heavy precipitation, raining days and intensity by area average show increasing trends in all grades. The total heavy precipitation in Grade Ⅳ and Ⅲ passes the 0.1 level test, and have distinct rising trend. The linear trend coefficients of total heavy precipitation, raining days, and intensity in different weather stations show various characteristics. With the percentiles decreasing, the trend coefficients show a decreasing trend in mid lower reaches of the Yangtze River from Yichang to its east, while opposite trend appears in southern Hunan and southern Jiangxi. For all grades, the total heavy precipitation breaks congruously in 1993, and shows a rising trend. The raining days breaks during the end of 1980s and the beginning of 1990s. The intensity begins to strengthen from 1994, but becomes unobvious after the year of 2000. For all grades, the heavy precipitation, raining days and intensity change regularly at an interdecadal period of 12—14 years and a short term period of 6—9 years.

     

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