中国夏季极端降水空间格局及其对城市化的响应（1961~2010）

利用1961~2010年6~8月中国544个气象站点的日降水数据，采用滑动空间百分位和滑动空间距平的方法来确定的极端降水阈值，在此基础上，以夏季极端降水的雨量占夏季总降水量的比例来表征极端降水强度，并检测极端降水阈值和强度的区域非均一性。进一步通过引入可以反映城市化水平的DMSP/OLS夜间灯光数据，并将不同气象站点所在区域的城市化水平划分为6个等级，从而分析城市化水平与极端降水强度的关系来定量评估城市化对极端降水强度的影响。结果表明，采用滑动空间百分位法和滑动空间距平能够有效诊断出城市化对极端降水的影响。相比于固定百分位阈值法，基于滑动空间百分位法确定的极端降水阈值和强度的空间分异格局更加对比鲜明，整体来看城市化已在很大程度上影响了中国夏季极端降水的阈值和强度，进而对其空间分异特征产生了显著作用。一方面城市化效应使得中国夏季极端降水阈值提高了1.68%，另一方面夏季极端降水的平均强度与城市化水平有着显著的线性关系，即城市化水平每提高一级，极端降水的平均强度增大0.62%。因此，城市化增大了极端降水的风险。 关键词： 极端降水；滑动空间百分位法；滑动空间距平；DMSP/OLS；城市化；中国

Spatial Pattern of Summer Extreme Precipitation and Its Response to Urbanization in China(1961-2010)

Urbanization and other human activities contribute to the changing climate on regional and global scales, including the increasing occurrence of extreme precipitation events in China in the past decades, but the relative importance of these urbanization, as compared to climatic factors, remains unclear. The main goal of this study was to determine the relative contributions of urbanization to the altered spatiotemporal patterns of extreme precipitation in China during the past several decades. We used daily precipitation data from 544 meteorological stations in China from 1961 to 2010, and gets the thresholds of extreme rainfall of each station by using the developed method called moving spatial percentile (MSP ). We uses the ratio of extreme precipitation to total precipitation as the indicator so as to reflect the intensity of extreme precipitation. Based on the DMSP/OLS night light datasets, the urbanization levels of meteorological stations are divided into six grades. Then we use MSP and moving spatial anomaly to quantify the impact of urbanization on the intensity of extreme precipitation by doing a series of correlation analysis. The results show that the spatial pattern of extreme precipitation intensity derived from MSP is more distinguishable. Urbanization make the threshold of extreme precipitation increased by 1.68％ and there is a significant linear correlation between extreme precipitation intensity and urbanization level, namely extreme precipitation intensity will increase by 0.62％ when the urbanization level increases by one grade. Our results suggest that the substantial increase in extreme precipitation across much of China during the past five decades is likely triggered by local and regional urbanization process. Our results call for a better understanding of local and regional anthropogenic impacts on climate, and the exacerbated extreme climate events as a potential consequence of urbanization. This highlights the need to explore more deeply the specific roles of a range of anthropogenic processes and their relative contributions to extreme precipitation at regional scales.