变暖环境下华北地区农业气象灾害风险评估Ⅲ:京津冀地区高温事件持续日数与强度联合重现期分析

Risk Assessment of Agricultural Meteorological Disasters in North China under Warming EnvironmentⅢ:Joint Return Period Analysis of the Duration and Intensity of Heat Events in Beijing-Tianjin-Hebei Region

基于京津冀地区27个气象站1960-2019年逐日最高气温数据识别高温事件,综合考虑高温事件持续日数和高温强度(≥35℃积温量)两个特征,利用Copula函数拟合高温事件两个特征的联合累积概率分布,以分析京津冀地区高温事件的重现期特征。结果表明:京津冀地区高温事件发生频次、严重程度的分布呈现南高北低,但发生频次、持续日数和日均强度的增幅呈现南低北高;对高温事件持续日数进行边缘分布拟合,POISS函数在所有站点效果均为最优;对高温强度进行拟合时,GEV函数在更多的站点效果最好;将高温持续日数和强度进行二维联合,应用最多的Copula函数为Symmetrised Joe-Clayton函数,其次为Frank函数;研究区持续5d以上的高温事件重现期多在5a一遇以上,北部地区达百年一遇以上。

Heat events were identified based on the daily maximum temperature data at 27 meteorological stations located in the Beijing-Tianjin-Hebei region from 1960 to 2019.The Copula function was introduced to fit the joint cumulative probability distribution of the two characteristics,taking into account the duration of heat events and the heat intensity(defined as≥35℃accumulated temperature),so as to obtain the joint return period of the heat events with arbitrary duration and heat intensity and analyze the return period characteristics of heat events in the Beijing-Tianjin-Hebei region.The results demonstrate that the distribution of the frequency and severity of heat events in the Beijing-Tianjin-Hebei region is higher in the south and lower in the north,but the increase in frequency,duration and average daily intensity is lower in the south and higher in the north;the effect of POISS function is optimal at all sites by fitting the edge distribution of the duration of heat events;when fitting the heat intensity,the GEV function works more efficiently at a greater number of station;when combining the duration and intensity of heat events in two dimensions,the Copula function used most is Symmetrised Joe-Clayton function,followed by Frank function;return period of heat events lasting more than five days in the study area exceeds once in five years, and once in 100 years in the northern region. The results of the study can provide a reference for heat disaster prevention and mitigation in the Beijing-Tianjin-Hebei region.