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分析季节性干旱时空特征和发生规律,可为全球气候变化背景下制定抗旱减灾对策提供理论依据.本研究利用南方15个省(市、区)的气象台站1959—2008年逐日降水、气温资料,以国家标准《气象干旱等级》中的降水量距平百分率作为干旱指标,并进行修正,计算了1959—2008年南方地区干旱指数,分析了年、季、月尺度干旱频率的空间分布特征、以及干旱强度、干旱站次比的年际变化.结果表明:研究期间,南方地区年尺度干旱风险总体较小.干旱空间特征存在明显的季节性差异,南方地区季节性干旱以秋旱发生频率最高、强度最重,其多发生在长江中下游地区和华南地区等主要农作区;其次为冬旱,主要发生在西南地区西部和华南地区等冬作区;春旱和夏旱较轻,春旱多发区在西南地区西南部、华南南部以及淮北等地,夏旱多发区在长江中下游地区、福建东南沿海和西南地区东北部.研究区干旱多发区呈明显的月际波动变化和空间转换,11月到次年5月,干旱多发区范围随季节推移减小,5—11月,干旱多发区范围随季节推移增大,4—6月干旱发生范围最小,11—12月干旱多发区范围最广.1959—2008年,南方地区年尺度干旱范围略有减小、干旱强度略有增强,但不同季节表现不尽相同:春旱范围略有减小、强度减轻,夏旱范围明显减小、强度减轻,秋旱范围明显增大、强度增重,冬旱范围减小、强度减轻.
Analysis of temporal and spatial characteristics and occurrence patterns of seasonal drought may provide a theoretical basis for formulating drought relief and mitigation strategies in the context of global climate change.This study used daily precipitation and temperature data from 1959 to 2008 in 15 southern provinces (cities and districts) Taking the percentage of precipitation anomaly in the national standard “Meteorological Drought Scale” as the indicator of drought, the drought index was calculated and the drought index of southern China from 1959 to 2008 was calculated. The spatial distribution characteristics of annual, seasonal and monthly drought frequency were analyzed. The results showed that the risk of annual drought in the southern part of China was generally small during the study period, with obvious seasonal differences in the spatial characteristics of drought, and the seasonal drought in southern China had the highest frequency of autumn drought, Which occurred most frequently in the middle and lower reaches of the Yangtze River and southern China. The second was winter drought, which occurred mainly in the winter and winter in the western and southern China. The spring and summer drought was light, and the spring drought Multiple areas in the southwestern Southwest, southern South China and Huaibei, summer drought prone area in the middle and lower reaches of the Yangtze River, Fujian southeast coast and southwestern region Northeast of the study area of arid multiple areas showed significant changes in monthly fluctuations and space conversion, November to next May, the scope of drought prone area decreases with the seasons, from May to November, the area of drought prone area increases with the seasons The drought range is the largest in April-June, and the most extensive in the drought-prone area from November to December. The annual drought range in the southern part slightly decreases from 1959 to 2008, while the drought intensity slightly increases, but in different seasons, The same: the spring drought range decreased slightly, the intensity reduced, the scope of summer drought decreased obviously, the intensity reduced, the range of autumn drought increased obviously, the intensity increased weight, the scope of winter drought reduced, the intensity reduced.