1951～2010年中国年代际累积暴雨时空格局变化的相关因素研究

Research on Related Factors to Decadal Accumulated Heavy Rainfall Spatio-temporal Patterns Change in China During 1951-2010

采用多种统计方法,解释1951～2010年中国年代际累积暴雨不断增加的现象。结果表明：快速城镇化因素极有可能是中国大面积暴雨增加的主因。在时间序列上,城镇化因素对中国年际暴雨雨量、雨日和雨强的方差解释分别为61.54%,58.48%,65.54%;自然因子方差解释分别为24.30%,26.23%,21.92%。在空间格局上,中国县级总人口密度和低能见度日数年均值的面板数据与中国年代际累积暴雨雨量、雨日和雨强显著相关,其空间相关系数随年代推移而不断增加,进一步表明快速城镇化因素可能触发了中国年代际大面积暴雨的显著增加。

Recent studies have noted a worldwide increase in the occurrence of extreme-precipitation events,this increase has been attributed to warming climate. Although other anthropogenic factors are recognized to be important, their relative contributions remain unclear. We use daily rainfall data from 659 meteorological stations in China, large scale climatic and anthropogenic indices to identify major causes of, and quantify their contribution to, a marked increase in heavy rainfall in 1951-2010. The decadal heavy rainfall amount（HRA）,heavy rainfall days（HRD） and heavy rainfall intensity（HRI） increased by 58.6-68.7, 46.5-60.2 and 7.1-11.5percent respectively. Our analysis suggests that although this trend could be explained by both large-scale climate phenomena, and local and regional anthropogenic activities, the latter such as urbanization, industrialization and associated air pollution have the strongest influence. Contributing roughly at the same magnitude,such factors explain 61.5, 58.5 and 65.5 percent of the variance in HRA, HRD and HRI, respectively, where as the large-scale climate phenomena explain only 24.3, 26.2 and 21.9 percent respectively. The expansion of spatial distribution of accumulated HRA and HRD over time shows a statistically significant and increasing correlation with the spatial distribution of population density and annual low-visibility days. Taken together, these results suggest that the substantial increase in heavy rainfall across large parts of China during the past six decades is very likely triggered by large scale and rapid urbanization, industrialization and associated air pollution. Previous studies linking urbanization to rainfall are mostly focusing on the impact on total rainfall and mostly considered only the local or city scale. Previous studies found urbanization as likely cause of increased heavy rainfall in India over five decades. Our results support this finding, but also show that urbanization is only one of the factors- industrialization and air pollution each contributes at equivalent magnitude. Our analysis is the first, to our knowledge, to establish urbanization, industrialization and air pollution as the primary cause of a nation- or sub-continental-scale increase in heavy rainfall over decades, and to quantify relative contributions of anthropogenic and climate factors. Our findings indicate that local anthropogenic processes may shift the regional climate beyond through GHG emissions. Such connections need to be better understood and reflected into the climate models. With cities in China increasingly experiencing extreme rainfall events, compounded by the increasing extreme summer heat in the same region, our findings call for a careful reevaluation of the risks of extreme weather in formulating national policies on urbanization, industrialization and environmental management in China in formulating. Rapidly growing and industrializing cities and nations will need to better control the air pollution, and to anticipate and accommodate these regional climate consequences, if they are to reduce the risk of flooding and waterlogging.