基于百分位数法的中国不同强度小时降雨频次空间分异格局及其变化模态研究(1961-2013)

高分辨率的降水数据有助于科学认识全球增暖背景下不同强度降雨事件的空间分异特征。采用1961—2013年中国545个气象观测站的小时降水数据,基于50%和90%分位数,将小时降水事件分为弱降雨、中等强度降雨、强降雨和总降雨四类事件,从气候态特征、波动特征、变化趋势和时空变化模态四个方面诊断了上述四类小时降雨频次的空间演变特征。结果表明:(1)基于50%和90%分位数阈值的方法表明中国小时降雨阈值具有明显的东高、西低,沿海高、内陆低的空间分异特征。(2)中国不同强度小时降雨频次在1961—2013年呈现出东南高、西北低的空间分异特征,其中从东北至西南存在一个介于东南和西北之间的过渡带,其不同降雨频次介于东南和西北之间。(3)中国不同强度小时降雨频次波动特征首先呈现出东南波动小,西北波动大;其次呈现出南方波动小,北方波动大的空间分异特征。中国不同强度小时降雨频次均在长江流域呈现出增加趋势,强降雨和总降雨频次在京津冀地区也明显趋于增加。(4)基于EOF分析的结果表明中国不同强度小时降雨频次在长江流域趋于增加是最主要的模态特征,该模态小时弱降雨、中等强度降雨、强降雨和总降雨频次的方差解释率分别达62.49%、59.41%、46.26%和67.20%。

Percentile method-based study on spatial differentiation patterns of hourly rainfall frequency with different intensities and their changing modes in China(1961 to 2013)

High resolution precipitation data is conductive to understand the spatial differentiation characteristics of the rainfall events with different intensities under the background of global warming.In accordance with the hourly precipitation data from 545 meteorological stations from 1961 to 2013 in China,the hourly precipitation events are divided into four types:weak rainfall,moderate intensity rainfall,heavy rainfall and total rainfall based on 50%and 90%quantiles,and then the spatial evolution characteristics of the above four types of the hourly rainfall frequency are diagnosed from the four aspects,i.e.climatological characteristics,fluctuation characteristics,change trend and temporal and spatial modes.The result shows that(1)it is indicated from the 50%and 90%quantile thresholds-based method that the hourly rainfall thresholds in China have obvious differentiation characteristics of high in the east,low in the west,high along the coast and low in the inland;(2)the rainfall events with different intensities from 1969 to 2013 in Chinaexhibit the spatial differentiation characteristics of high in the southeast and low in the northwest,in which a transitional zone is there between the southeast and the northwest with different rainfall frequencies between the southeast and the northwest;(3)the fluctuation characteristics of hourly rainfall frequencies with different intensities in China exhibit small in the southeast and large in the northwest at first,and then exhibit the spatial distribution characteristics of small fluctuation in the south and large fluctuation in the north;while all the hourly rainfall frequencies with different intensities in China exhibit increasing trends along the Yangtze River Basin and the frequencies of heavy rainfall and total rainfall tend to be obviously increased in Beijing-Tianjin-Hebei region;(4)it is indicated from the result of the EOF analysis that the increasing tendencies of the hourly rainfall frequencies with different intensities in China along the Yangtze River Basin are the mainest modes , of which the variance interpretation rates of the frequenciesof hourly weak rainfall , rainfall with moderate intensity , heavy rainfall and total rainfall are 62 . 49 % , 59 . 4 1% , 4 6. 2 6 % and 67. 20 % respectively .