基于MCI的河西走廊东部近60年干旱特征及对厄尔尼诺事件的响应

Characteristics of drought and response to El Ni?o events over the last 60 years in eastern Hexi Corridor based on MCI

摘要:

2023年河西走廊东部遭遇了60 a一遇的高温干旱事件，造成巨大经济损失。为准确预报预测极端灾害天气并减轻其造成的危害，基于河西走廊东部国家基本气象站1961—2020年的逐日气象数据和国家气候中心发布的厄尔尼诺（El Ni?o）事件记录，利用逐日气象干旱综合指数MCI，采用气候统计学方法分析不同尺度下的干旱日数和干旱过程特征，探讨气象干旱综合指数对El Ni?o的响应。结果表明：该区域干旱日数以轻旱最多，占总日数的62.0%，特旱最少，占3.5%，中旱及以上日数古浪最多，为51.6 d，民勤最少，为19.3 d；干旱日数5月最多，为5.1 d，1月最少，为2.1 d，中旱及以上日数4月最多，为2.2 d，1月最少，为0.5 d。年平均干旱过程为1.0次，古浪最多，为1.3次，民勤最少，为0.7次；干旱过程平均持续时间为64.3 d，民勤持续时间最长，为78.2 d，天祝最短，为51.8 d；干旱过程强度特征为一般干旱占比最大，占47.9%，特强干旱占比最小，占5.2%，较强及以上干旱凉州和民勤最多，占56.7%，古浪最少，占47.3%。El Ni?o持续期间气温以正常为主，偏高年份发生气候异常的概率较高；降水以偏少为主，偏多年份易出现气候异常；干旱日数偏多，中旱及以上日数南部山区偏多较明显，El Ni?o是造成研究区干旱严重的主要原因之一。

Abstract:

The 2023 heat and drought event in eastern Hexi Corridor, the worst in 60 years, caused significant economic losses. In order to accurately forecast and mitigate the effects of extreme weather events, based on daily meteorological data at the basic national meteorological stations in the eastern Hexi Corridor and the El Ni?o events records from the National Climate Center from 1961 to 2020, the meteorological drought composite index (MCI) was used to analyze the drought days and the characteristics of the drought process at different scales by the climatic statistics method, and the response of the meteorological drought composite index to El Ni?o was discussed.?The results showed that light drought days were the most frequent in the region, accounting for 62.0% of the total days, the least was extreme drought, accounting for 3.5%. The maximum number of days above moderate?drought was 51.6 days in Gulang and the least was 19.3 days in Minqin. May has the highest number of dry days at 5.1 days, January has the lowest at 2.1 days, April has the highest number of days with moderate drought or above at 2.2 days, and January has the lowest at 0.5 days. The average annual drought process was 1.0 days, the most was 1.3 days in Gulang and the least was 0.7 days in Minqin.The average duration of a drought process was 64.3 days, the longest in Minqin was 78.2 days, and the shortest in Tianzhu was 51.8 days. The drought process intensity was characterized by general drought?accounted for the largest 47.9% and the lowest proportion of extreme drought was 5.2%, Stronger than the drought accounted for the largest 56.7% in Liangzhou and Minqin and the lowest was 47.3% in Gulang. During the continuous period of El Ni?o, the temperature in the area is mainly normal, and the probability of climate anomalies occurring in higher years is higher; Precipitation is mainly low, and climate anomalies are prone to occur in years with high precipitation; The number of dry days is relatively high, with more moderate and above days in the southern mountainous areas, El Ni?o was one of the main causes of severe drought in the study area.