气候变暖背景下中国干旱变化的区域特征

在全球气温日趋升高和极端降水增加的气候背景下，近年来中国干旱变化特征异常突出，新形势下需进一步深入认识干旱发生特征及影响机制。利用1960-2014年中国527个气象站逐日气温和降水量数据，选用改进的综合气象干旱指数（MCI）作为干旱监测指标，详细分析了中国各区域干旱强度、次数和持续时间变化特征及其差异性。结果表明：1960年以来，中国各区域干旱程度加重，范围增大，次数增多，持续时间增长。干旱特征发生了明显的区域变化，各个区域干旱变化差异显著。西南、华中、华北和华南区域干旱程度明显加重，主要是重度以上干旱次数较多。华北和西南干旱年数最多，为45年，其他地方为35~36年，华北重度以上干旱年份最多，为14年，其次是东北和华南的7年。干旱发生时间和区域也有随机性，中国各区域四季都有可能发生干旱，干旱不仅发生在北方干旱和半干旱区域，在南方湿润和半湿润区域同样发生。各区域以夏旱为主，东北以春旱和夏旱居多，华南以秋旱为主。干旱持续时间不等，有时高达9个月。有些区域年内干旱呈单峰型，有些区域为双峰型。气候变暖背景下，中国各个区域干旱呈加重趋势。

Regional Characteristics of Drought in China under the Background of Climate Warming

Under the climate background of global warming, the characteristics of drought change are very prominent in recent years in China, and the understanding of the mechanism of drought disaster needs to be further deepened under the new situation. The improved comprehensive meteorological drought index (MCI) was selected as the monitoring index for drought based on the daily temperature and precipitation data of 527 meteorological stations from 1960 to 2014 in China, and the variation characteristics and differences of drought intensity, frequency and duration were analyzed systematically in seven regions of China. The results show that the range, severity, frequency and duration of drought increase in China under the background of climate warming. The characteristics of drought had obvious regional changes, and there were significant differences among seven different regions. The degree of drought significantly increased in southwest, central, north and south China. The total number of droughts was 45 years in north and southwest China, while it was 35-36 years in other places, and the number of severe or above droughts was mainly more. The most severe drought years were 14 years in north China, followed by 7 years in northeast and south China. The time and region of drought are also random. Drought may occur in all seasons,but the drought happened mainly in summer in China, mostly happened in spring and summer in northeast, and mainly happened in autumn in south. The duration of drought sometimes is as long as nine months. In some regions, the drought pattern is one peak, while it is two peaks in some areas. The drought in north is heavier and lasts longer than south. Moreover, drought occurs not only in the arid and semi-arid regions of the north, but also in the humid and semi-humid regions of the south. Under the background of climate warming, the drought is increasing in all regions of China, not only in three regions of the northern, but also in four regions of the southern.