基于多维Copula函数的澜沧江-湄公河流域气象干旱特征分析OACSTPCD

In order to comprehensively unveil multidimensional meteorological drought characteristics of the Lancang-Mekong River Basin under changing environments,the standard precipitation evapotranspiration index(SPEI)was used to characterize meteorological drought in the basin.Drought events in the Lancang River and the upper,middle,and lower reaches of the Mekong River during 1901-1960 and 1961-2021 were extracted based on the run theory,and two-dimensional and three-dimensional drought characteristic variable joint distributions for different sub-basins in the two periods were constructed using the Copula function.Through the calculation of the drought joint occurrence probabilities under different combinations of characteristic variables,the spatio-temporal changes in multidimensional meteorological drought characteristics in different sub-basins were compared and analyzed.The results show that in terms of time,the average drought severity of each sub-basin during 1961-2021 was higher than that during 1901-1960,especially the joint occurrence probabilities of extreme drought events(with univariate cumulative frequencies of 25%and 50%)increased the most.In terms of space,during 1961-2021,with the increases in drought duration,drought intensity,and drought peak intensity,the area with the highest value of multi-dimensional drought joint occurrence probabilities in the"or"case shifted southward from north,while in the"and"case,it shifted northward from south.