近120年中国干旱年际变化特征及主要的影响因子

Interannual Variability and Key Influencing Factors of Drought in China over the Past 120 Years

基于1901~2020年标准化降水指数(SPI-12)、标准化降水蒸散指数(SPEI-12)和自校准的帕默尔干旱指数(scPDSI)的数据集,研究了中国区域近120年干旱的长期变化特征,并进一步分析了3种干旱指数在中国区域存在差异的原因。结果表明:中国西南、黄土高原、东北南部及新疆南部有显著变干的趋势;西北东部、东北北部和华北有显著变湿的趋势。就干旱事件而言,东北和西北地区干旱持续时间长且强度大,但总体呈现减小的趋势,特别是在西北东部和东北北部;相反,东北南部干旱事件的持续时间和强度均有所增加。全国每年约有282万平方公里遭受干旱,约30.5万平方公里遭受特旱。不同严重程度的干旱面积均呈增加趋势,且在20世纪90年代中期快速增长。此外,干旱面积存在显著的年际和年代际变化特征,周期分别为2~3年和18~22年。进一步对比发现,SPEI-12在湿润地区与SPI-12及scPDSI有较好的一致性,而在干旱半干旱地区一致性相对较差。在湿润地区,降水的盈缺主导该地区的干湿变化,而在干旱半干旱地区,除降水外,气温异常和土壤特性对干旱的贡献也不容忽略。因此,在全球变暖的背景下,针对干旱半干旱地区的研究要慎重选择干旱指数。

This study examines the long-term patterns of drought in China over the past 120 years using datasets from three drought indices:the Standardized Precipitation Index(SPI-12),Standardized Precipitation Evapotranspiration Index(SPEI-12),and self-calibrated Palmer Drought Severity Index(scPDSI)covering the period from 1901 to 2020.The research investigates the reasons behind the inconsistencies observed in these indices.The results reveal a significant drying trend in Southwest China,the Loess Plateau,southern Northeast China,and southern Xinjiang while wetting trends are notable in eastern Northwest China,northern Northeast China,and North China.Drought events in Northeast China and Northwest China are characterized by prolonged duration and higher intensity,although there is a general trend of decreasing drought,particularly evident in eastern Northwest China and northern Northeast China.In contrast,southern Northeast China exhibits a decreasing trend of drought duration and intensity.Every year,about 2.82×106 km2 of land areas experience drought,with about 3.05×104 km2 of land areas threatened by extreme drought.Drought-affected areas of varying severity have increased over time,showing rapid growth after the mid-1990s.Additionally,the drought area exhibits significant interannual and decadal variabilities,with periods of 2–3 years and 18–22 years.In humid regions,the three drought indices show good consistency,while in semi-arid and arid regions,their consistency is relatively low.In humid areas,wet–dry variation is primarily influenced by precipitation.In semi-arid and arid areas,in addition to precipitation,temperature and soil characteristics also play important roles in drought variations.Therefore,more attention should be paid to drought index selection over arid and semi-arid areas in the context of global warming.