近52a长江中下游地区极端降水的时空变化特征

长江中下游地区是我国主要农业区,同时也是降水异常,洪涝灾害频繁发生的地区之一,对长江中下游地区极端降水变化的研究,可以为该区农业生产及防洪减灾提供参考依据。利用1961~2012年间的长江中下游地区84个站点的逐日降水观测资料,基于年最大日降水(AM)序列与超门限峰值降水(POT)序列,通过滑动平均、Mann-Kendall检验法、线性倾向估计等方法,分析了该地区极端降水事件的时空变化特征。结果表明:(1)长江中下游地区近52a来极端降水量呈现为较明显的增加趋势,且极端降水量速率为9.3mm/10a,存在较为明显的年代际波动变化特征,1990年以后进入极端降水量偏多的时期;(2)AM与POT序列多年平均值大值主要分布在江西省大部、湖北东南部以及安徽南部;AM与POT序列多年标准差大值主要分布江西东南部与北部,湖北东南部以及湖南西北部;AM序列多年平均值与标准差均高于POT序列,AM序列年际间振幅要明显强于POT序列,极端降水年际变化幅度大于年内变化;(3)长江中下游沿岸地区年最大日降水量主要表现为增加趋势,长江以北的西部地区则主要表现为减少趋势;长江沿岸地区以及中东部地区的极端降水量主要表现为增加趋势,西部地区则主要表现为减少趋势。

SPATIO-TEMPORAL VARIATIONS OF THE EXTREME PRECIPITATION OF MIDDLE AND LOWER REACHES OF THE YANGTZE RIVER IN RECENT 52 YEARS

Middle and Lower Reaches of the Yangtze River is not only the main agriculture region of China, but also one of the areas with precipitation anomalies and frequent floods. The study of the tendency of extreme precipitations of Middle and Lower Reaches of the Yangtze River can provide a reference for agricultural production and local flood control and disaster mitigation. Daily precipitation data from 84 meteorological stations in the Middle and lower reaches of the Yangtze River during 1961-2012 were used to derive annual maximum series (AM) and peak over threshold series (POT). We used moving average, Mann-Kendall test, linearity trend estimation and other methods to study the changes of extreme precipitation events. The results showed that (1) in the past 52 years, the extreme precipitation in the Middle and lower reaches of the Yangtze River had significantly increased, the extreme precipitation rate was 9.3 mm per 10 years, the extreme precipitation had inter-decadal variation, and since 1990 the extreme precipitation had increased obviously. (2) The maximum perennial average value and standard deviation of the spatial distribution of AM and POT were the highest in Jiangxi Province, the southeastern of Hubei Province and the southern of Anhui Province. The maximum standard deviation of the spatial distribution of AM and POT occurred in the southeastern and northern of Jiangxi Province, the southeastern of Hubei Province and the northwestern of Hunan Province. It is large in the central part and small at the north and west part. The perennial average value and standard deviation AM were larger than POT, and the annual fluctuation was significantly stronger than POT. The annual fluctuation of the extreme precipitation was larger than the annual variation. (3) The annual maximum daily precipitation along the Yangtze River had an increasing trend, and the western region of the Yangtze River's northern showed a decreasing tendency. The extreme precipitation along the Yangtze River, the middle area and the eastern region mainly showed an increasing trend, and the western region showed a decreasing tendency. In the past 52 years, the extreme precipitation of Middle and Lower Reaches of the Yangtze River had an increasing tendency, and the extreme precipitation rate was 0.93 mm/year. The extreme precipitation of Middle and Lower Reaches of the Yangtze River expression annual variation, the trend was low-high-low-high-low-high. The annual maximum daily precipitation of Middle and Lower Reaches of the Yangtze River showed a significant increasing and strengthen tendency. The extreme precipitation of each station also showed an increasing trend, but the variation degree was different. After 21 century the extreme precipitation times of Chuzhou station did not change obviously, but the extreme precipitation strength was increasing, so the precipitation was more concentrated.