基于标准化降水蒸散指数分析湖南各气候区干旱事件重现期

Analysis of Recurrence Period of Drought Events in Various Climatic Regions of Hunan Province Based on Standardized Precipitation Evapotranspiration Index

湖南省气候条件复杂,干旱发生概率高,为揭示湖南省各气候区(湘中、湘东北、湘西北、湘西和湘南)干旱事件的概率特征,基于湖南省97个气象站点1961−2020年的气象资料,采用标准化降水蒸散指数(SPEI)和Copula函数等方法,提取干旱事件的历时及烈度,研究湖南省各气候区干旱历时与烈度的同现重现期。结果表明:(1)沿湘南、湘中、湘东北、湘西北、湘西的方向上,气候区的干旱事件数由多到少,干旱事件历时及烈度的数值范围由小到大。(2)干旱历时与烈度分别进行最优边际分布函数的拟合时,GEV函数拟合的站点数均超过60%,且干旱烈度的最优边际分布函数拟合效果优于干旱历时。建立干旱历时与烈度最优边际分布的联合函数时,Frank Copula函数应用超过50%的站点。(3)湘南地区易发生干旱历时较短且烈度较大的干旱事件,湘西地区、湘西北地区及湘东北部分地区易发生干旱历时较长且烈度大的干旱事件。湘中地区易发生干旱历时较长且烈度大的干旱事件,湘中偏南地区易发生干旱历时较短且烈度较大的干旱事件。湖南省各气候区干旱事件的概率特征存在差异,需针对其概率特征采取措施,减轻干旱的危害。

The climatic conditions in Hunan province are complex and the probability of drought occurrence is high.To reveal the probability characteristics of drought events in various climatic regions of Hunan province(central Hunan,northeast Hunan,northwest Hunan,western Hunan,and southern Hunan),based on meteorological data from 97 meteorological stations in Hunan province during 1961−2020,standardized precipitation evapotranspiration index(SPEI)and Copula function were used to extract the duration and severity of drought events,and to study the co-occurrence recurrence periods of drought duration and severity were studied in each climatic region of Hunan province.The results showed that:(1)along the direction of southern Hunan,central Hunan,northeast Hunan,northwest Hunan,and western Hunan,the number of drought events in the climatic region was from more to less,and the value range of drought events duration and severity was from small to large.(2)When fitting the optimal marginal distribution function of drought duration and severity respectively,the number of stations fitted by GEV function exceeds 60%,and the fitting effect of the optimal marginal distribution function of drought severity was better than that of drought duration.When the joint function of drought duration and the optimal marginal distribution of severity was established,the Frank Copula function was applied to more than 50%of the sites.(3)Southern Hunan was prone to shorter duration and greater severity of drought events,while western Hunan,northwest Hunan,and some areas of northeast Hunan were prone to longer duration and greater severity of drought events.Central Hunan was not only prone to drought events with long duration and high severity but also to drought events with short duration and high severity in the southern part of central Hunan.There were differences in the probability characteristics of drought events in different climatic regions in Hunan province,and measures can be taken to reduce the harm of drought.