气候变暖背景下中国干旱强度、频次和持续时间及其南北差异性

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灾害影响机制。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）作为监测指标，详细分析了中国干旱强度、频次和持续时间变化特征及其南北差异性。结果表明：气候变暖背景下，中国干旱范围扩大、程度加剧、频次增加；干旱发生的范围发生了明显的转移，北方干旱加剧的同时，南方干旱明显加重，尤其是大旱范围明显增加。中国干旱范围主要在黄河流域以南和长江以北地区。干旱频次北方高于南方，东部高于西部，长江流域以北干旱频次较高。中国干旱持续时间较长，而且四季都有可能发生干旱。干旱不仅发生在干旱区和半干旱区，湿润和半湿润区域也常有干旱发生。不同年代、不同区域干旱发生的程度、持续时间和频次有一定的差异。中国20世纪90年代中后期至21世纪初期干旱范围最广、持续时间最长，造成的损失最严重。中国干旱强度、频次和持续时间南北差异性显著。气候变暖后，中国干旱强度加重、范围扩大、频次增加和持续时间增加明显。

Drought Severity,Frequency, Duration and Regional Differences in China

This paper examines daily air temperature and precipitation data from 1960 to 2014 from 527 meteorological stations in China. The improved Meteorological Comprehensive Drought Index (MCI) is taken as indication of drought monitoring to analyze the spatial-temporal characteristics of drought severity, frequency, duration, and regional differences in China. The results show that drought scope has expanded in China, and the severity and frequency has increased in the context of climate warming. The scope of the drought is also changing, with drought intensifying in the north China and increasing substantially in the south China, especially in areas of severe drought. The drought was the most widespread and sustained in the late 1990s and 2001-2010 in China, mainly afflicting to the south of the Yellow River and north of the Yangtze River. In general, the drought level, duration, and frequency were higher in the north China than the south China and higher in the east China than the west China. Drought is likely to occur year-round in China, but the degree of occurrence, range, duration, and frequency differs across years and regions. The north-south differences of drought frequency and duration are significant.