基于SPI和SPEI指数的锡林郭勒草原干旱时空变化特征

Temporal and spatial variation of drought in the Xilingol grassland based on the standardized precipitation index and standardized precipitation evapotranspiration index

草原作为陆地生态系统的主体,对全球气候变化具有重要影响。研究草原干旱的时空分布,探讨适用性较高的干旱指数,对该地区干旱监测和评估具有重要科学意义。本研究利用1990-2019年锡林郭勒盟地区9个气象站点的逐月降水量和月平均温度资料,计算干旱指数[标准化降水指数(SPI)和标准化降水蒸散指数(SPEI)]并且采用Mann-Kendall检验方法,分析该区域年和季节尺度上干旱的趋势性、突变型以及年干旱频率并进行时空变化特征对比研究。结果表明:1)时间上,两种指数均识别出该地区旱化趋势加剧,SPEI监测到的干旱变化趋势比SPI监测到的变化趋势明显;春季SPI监测到该地区呈湿润化趋势,SPEI监测到的则相反,两种指数在夏季均监测出显著的旱化趋势(P<0.05),秋、冬季节均呈现出湿润化的趋势。2)空间上,SPEI监测到的干旱范围比SPI监测到的大,锡林郭勒盟中部到西部干旱程度最严重。3)干旱频率上,SPEI监测到的重旱事件比SPI监测出的多;4)两种指数均无突变点。总得来看,在评估锡林郭勒盟草原干旱情况时,SPEI比SPI具有更好的适用性。

As the main terrestrial ecosystem,grasslands have an important impact on global climate change.It is of great scientific significance to study the temporal and spatial distribution of grassland drought and explore the drought index with high applicability for drought monitoring and evaluation in this ecosystem.This study analyzed the spatial and temporal distribution characteristics of annual and seasonal meteorological droughts and the trends,mutations,and annual drought frequencies using the drought indices of the standardized precipitation index(SPI)and standardized precipitation evapotranspiration index(SPEI),as well as the Mann-Kendall test,based on the monthly precipitation and monthly mean temperature data of the Xilingol League 9 meteorological stations from 1990 to 2019.The results showed that:1)Both indexes identified an increasing trend of drought in the region,and the SPEI was more significant than SPI(P<0.05).In spring,SPI showed a wetting trend,whereas SPEI showed a drought trend.Both indexes showed a significant drought trend in summer(P<0.05)and showed a wetness trend in autumn and winter.2)The drought range detected by SPEI was larger than that detected by SPI,and the drought was the most severe from the central to western part of the Xilingol League.3)SPEI detected more severe drought events than the SPI.4)There were no mutation points in either index.In general,SPEI has a better applicability than SPI in evaluating drought conditions in the Xilingol League.