我国干旱半干旱区近60 a气象干旱气候特征分析

Analysis of climatic characteristics of meteorological drought in arid and semi-arid regions of China in recent 60 years

为研究我国干旱半干旱区连续无雨日气候特征的变化趋势,利用该区域74个气象站1961—2022年逐日降水观测资料,对研究区连续无雨日变化特征及其在1961—1990年和1991—2020年前后两个时段的差异等进行分析,重点关注16 d及以上连续无雨日,并将16~25 d、26~40 d、41~60 d、60 d以上连续无雨日分别定义为轻旱、中旱、重旱和特旱。结果表明:我国干旱半干旱气候区16 d及以上连续无雨日的发生次数和日数存在明显差异,尤其是重旱、特旱对应的连续无雨日发生次数和日数,干旱区分别是半干旱区的2.0倍与6.0倍左右;1991—2020年与1961—1990年相比,研究区西部不同等级气象干旱发生次数明显减少,而中东部有所增加;研究区西部不同等级干旱发生日数同样减少明显,中部轻旱和中旱发生日数减少,而重旱和特旱发生日数有所增加;研究时段内,该区域绝大部分气象站点不同等级干旱发生次数和日数均未发生突变。

In order to study the variation trend of climatic characteristics of consecutive dry days(CDDS)in arid and semi-arid regions of China the variation characteristics of CDDS and their differences in the period of 1961-1990 and 1991-2020 in the study area were analyzed by using the daily precipitation data from 74 meteorological stations in arid and semi-arid regions of China from 1961 to 2022.The CDDS equal to 16 days and above were focused on,and the CDDS of 16 to 25 days,26 to 40 days,41 to 60 days and above 60 days were defined as partial drought,moderate drought,severe drought and extreme drought,respectively.The results show that there are sig⁃nificant differences in the occurrence times and days of CDDS for 16 days and above in arid and semi-arid climates in China.Espe⁃cially,the occurrence times and days of CDDS corresponding to severe drought and extreme drought in arid regions are about twice times and six times of those in semi-arid regions,respectively.Compared with the period of 1961-1990,during 1991-2020,the fre⁃quency of meteorological drought with different grades in the western part of the study area decreased significantly,while it increased in the central and eastern parts of the study area.In the western part of the study area,the number of drought days with different grades also decreased obviously,the number of partial and moderate drought days decreased,and the number of severe and extreme drought days increased.The significance test of difference show that there was no mutation in the frequency and days of drought with different grades at most meteorological stations in the arid and semi-arid regions.