1980—2020年内蒙古暖季复合干旱热浪事件变化特征

Analysis of the variation characteristics of compound drought heatwave events during the warm season in Inner Mongolia from 1980 to 2020

为了强化对复合干旱热浪事件(CDHEs)的监测,选择内蒙古作为研究区,基于115个站点数据,运用标准化降水蒸散指数和高温相对阈值法,对该区干旱和热浪事件进行定义与识别。并在此基础上,构建复合干旱热浪强度指数(CDHMI)进行复合干旱热浪频率(CDHF)统计,继而开展干旱、热浪和CDHEs时空变化特征研究。结果显示:暖季(5—10月)不同时间尺度(1个月和6个月尺度)干旱强度皆呈增加趋势。内蒙古西部和通辽市中部干旱频发,中东部地区干旱发生频率显著增加。热浪频率显著增加、热浪期显著延长,热浪持续时间和强度呈非显著增加趋势。热浪频率、持续时间和强度总体呈现西高东低的空间分布格局。CDHEs发生的频率和强度呈现显著增加趋势,特别是1998年之后。空间分布上,CDHF高值区集中在锡林郭勒盟和呼伦贝尔市,内蒙古北部地区CDHF明显增多,而高强度CDHMI分布在内蒙古东北和西南地区,增长趋势与CDHF相似。

To enhance the monitoring of compound drought and heatwave events(CDHEs),Inner Mongolia was selected as the study area.Based on data from 115 stations,the drought and heatwave events in this region were defined and identified using the Standardized Precipitation Evapotranspiration Index and the high-temperature relative threshold method.On this basis,a Compound Drought and Heatwave Magnitude Index(CDHMI)was constructed to statistically analyze the Compound Drought and Heatwave Frequency(CDHF),and then a study on the spatiotemporal variation characteristics of droughts,heatwaves,and CDHEs was carried out.The results show that during the warm season(May to October),the intensity of droughts at different time scales(1-month and 6-month scales)is increasing.The western part of Inner Mongolia and the central part of Tongliao City are prone to frequent droughts,and the frequency of droughts in the central and eastern regions has significantly increased.The frequency of heatwaves has significantly increased,and the period of heatwaves has been significantly extended,with the duration and intensity of heatwaves showing a non-significant increasing trend.The frequency,duration,and intensity of heatwaves generally show a spatial distribution pattern of being higher in the west and lower in the east.The frequency and intensity of CDHEs have shown a significant increasing trend,especially after 1998.Spatially,high values of CDHF are concentrated in the Xilingol League and Hulunbuir City,with a significant increase in CDHF in the northern region of Inner Mongolia,while highintensity CDHMI is distributed in the northeastern and southwestern regions of Inner Mongolia,with a growth trend similar to that of CDHF.