西江流域降水气温关系变异诊断及驱动力分析

Diagnosis and driving force analysis of variations in precipitation-temperature relation of Xijiang River basin

气候变化的加剧和气象灾害频发,使得西江流域的降水-气温相依结构是否发生变化及其背后的驱动力尚不明晰。本文基于Copula函数的极大似然比(CLR)方法,对两者的相依结构进行变异诊断,并考虑当地气象因子和遥相关因子,探究变化背后的驱动力。结果表明,西江上游流域降水-气温相依结构在2002年2月发生了变异,郁江流域在1985年4月发生了变异。风速、相对湿度在全时间序列中和其相依结构有着较显著的正、负相关关系,并且北极涛动是主要驱动力,它影响着东亚季风,然后对当地风速产生影响,进而影响降水-气温关系,使其相依结构发生了显著变异。

Intensification in climate change and frequent human activities makes it unclear whether or not the precipitation-temperature dependent structure in the Xijiang River basin has changed and what are the driving forces behind it.Using the maximum likelihood ratio(CLR)method of Copula functions,this paper presents a diagnosis of the structure changes and explores the driving forces behind the change through considering the factors of local meteorology and remote correlation.The results show that a sudden change in this structure occurred in the upper Xijiang basin in February 2002 and also in the Yujiang basin in April 1985.Wind speed has significant positive correlation with the dependent structure of the whole time series,but relative humidity is correlated negatively.We found that arctic oscillations are the main driving force that impacts the East Asian monsoon and then on the local wind speed,and variations in the latter can modify the precipitation-temperature relationship,thereby causing significant variations in the dependent structure.