透视中国小时极端降水强度和频次的时空变化特征(1961～2013年)

极端降水事件具有小概率和高风险的特征,采用高分辨率数据有助于了解极端降水真实情况。采用1961～2013年中国小时降水数据,从极端降水的强度和频次特征出发,采用多种数理统计方法诊断中国小时极端降水的时空变化特征。结果表明:(1)不同重现期下的中国小时极端降水强度具有明显的东南高-西北低的空间分异特征。不同百分位数下的中国小时极端降水阈值也具有东南高-西北低的空间分异特征。(2)不同百分位数下的1961～2013年中国小时极端降水频次变化趋势主要以增加趋势为主,且随着百分位数的增加,增加趋势趋于减小并向长江流域地区集中。中国小时极端降水频次波动特征则呈东南波动小-西北波动大的空间分异格局,且随着百分位数的增加波动大的地区从西北向东部和南部地区扩张,同时西部地区逐渐呈现出波动大小镶嵌的格局。(3)90%和95%分位数下的中国小时极端降水频次EOF分析表明,中国小时极端降水频次具有明显不同的时空变化模态,且前两个模态可以反映中国小时极端降水频次的主要时空变化模态。两种超阈值取样方法均反映了长江流域呈增加趋势的时空模态特征。

Temporal and Spatial Variation Characteristics of Intensity and Frequency of Hourly Extreme Precipitation in China from 1961 to 2013

Extreme precipitation events have the characteristics of low probability and high risk. The use of high resolution dataset is helpful to understand the real situation of extreme precipitation. Based on the dataset of China's hourly precipitation from 1961 to 2013, the characteristics of the intensity and frequency of extreme precipitation in China were analyzed by various mathematical statistics methods. The results showed that: Firstly, the intensity of hourly extreme precipitation in China at different return periods had obvious spatial differentiation characteristics of high in southeast and low in northwest. The hourly extreme precipitation thresholds in China under different percentiles also had the spatial differentiation characteristics of high in southeast and low in northwest. Secondly, the trend of hourly extreme precipitation frequency in China from 1961 to 2013 under different percentiles were mainly increasing, and with the increase of percentiles, the increasing trend tended to decrease and concentrated in the Yangtze River Basin. The fluctuation of hourly extreme precipitation frequency in China showed a spatial pattern of small fluctuation in the southeast and large fluctuation in the northwest. With the increase of percentiles, the areas with large fluctuation expanded from the northwest to the east and south, while the western areas gradually showed a mosaic pattern of fluctuation small and large. EOF analysis of China's hour extreme precipitation frequency under 90% and 95% percentile showed that the hourly extreme precipitation frequency in China had distinct temporal and spatial variation modes, and the first two modes could reflect the main temporal and spatial variation modes of the hourly extreme precipitation frequency in China. The two methods of super threshold sampling reflected the temporal and spatial characteristics of the Yangtze River Basin.