宁夏干旱的时空特征与大气环流响应关系

目的]探究宁夏地区干旱时空变化特征及其原因,对于干旱预防与应对决策具有重要意义。方法]基于宁夏自治区24个气象站点逐日资料,利用标准化降水蒸散指数(SPEI)。运用MK非参数检验与反距离权重插值分析了不同尺度下的干旱时空变化,通过Person相关系数分析定量分析了宁夏干旱指数对于大气环流的响应,结果](1)1982—2020年各尺度SPEI干旱指数经历了增大—减小—增大的过程,并在1990—2010年旱频发。(2)季尺度干旱指数空间分布差异明显,春季干旱频率较大,主要分布在北部的引黄灌区,且中旱、重旱较多,春季、夏季的干旱呈明显加重趋势,秋、冬季则呈湿润趋势,但秋、冬季干旱烈度相对春、夏季更为强烈。(3)ENSO暖事件期间宁夏SPEI值有减小趋势,ENSO冷事件期间SPEI指数有增加趋势,ENSO暖事件期间相对于ENSO冷事件期间更为干旱。(4)宁夏全境受到NAO与AO指数影响明显,无滞后关系,SOI指数滞后4个月与宁夏SPEI值相关性最大,主要影响宁夏的北部地区,PDO指数滞后6个月相关性最为显著,MEI指数滞与ENSO指数分别滞后3个月与5个月相关性最好,但与宁夏地区干旱相关性较弱。结论]干旱是宁夏的主要气象灾害,分析宁夏地区的干旱的时空变化与大气环流的响应关系,可为宁夏地区的干旱事件预防和气候变化区域适应对策提供参考。

Temporal and Spatial Characteristics of Droughts and Their Responses to Atmospheric Circulation in Ningxia

Objective]Exploring the spatial and temporal characteristics of drought in Ningxia region and its causes is important for drought prevention and response decisions. Methods] Based on the daily data of 24 meteorological stations in Ningxia Autonomous Region, the standardized precipitation evapotranspiration index(SPEI)was used. The MK nonparametric test and inverse distance weight interpolation were used to analyze the temporal and spatial variation of drought at different scales, and the response of Ningxia drought index to atmospheric circulation was quantitatively analyzed by Person correlation coefficient analysis. Results](1)In 1982—2020, the SPEI drought index of each scale experienced the process of increasing-decreasing-increasing, and drought occurred frequently from 1990 to 2010.(2)The spatial distribution of the drought index on the seasonal scale is obviously different. The drought frequency is higher in spring, mainly distributed in the northern Yellow River irrigation area, and there are more moderate and severe droughts. The drought in spring and summer is obviously aggravating, and in autumn and winter is humid, but the drought intensity in autumn and winter is more intense than that in spring and summer.(3)The SPEI value of Ningxia decreased during the ENSO warm event, and the SPEI index increased during the ENSO cold event. The ENSO warm event was drier than the ENSO cold event.(4)The whole territory of Ningxia is significantly affected by the NAO and AO indices, and there is no lag relationship. The SOI index has the greatest correlation with the SPEI value of Ningxia with a lag of 4 months, which mainly affects the northern area of Ningxia. The PDO index has the most significant correlation with a lag of 6 months. The MEI index had the best correlation with the ENSO index with a lag of 3 months and 5 months respectively, but the correlation with the drought in Ningxia was weaker. Conclusion] Drought is the main meteorological disaster in Ningxia. The analysis of the response relationship between the temporal and spatial changes of drought in Ningxia and the atmospheric circulation provides a reference for the prevention of drought events in Ningxia and regional adaptation to climate change.