广西1961~2022年寒潮气候变化特征及大气环流异常分析

Climate Change Characteristics of Cold Waves in Guangxi from 1961 to 2022 and Their Relationship with Atmospheric Circulation

研究全球变暖背景下低温寒潮的演变趋势是气候变化研究的基本问题之一,为人类的生产生活提供重要信息。本研究利用广西1961~2022年75个气象台站逐日平均气温和最低气温数据,根据广西寒潮标准,计算近61个寒潮年单站和区域的寒潮日数、频次和强度,并利用WS2001线性趋势变化评估方法、相关分析和合成分析等方法,研究了广西寒潮演变规律和大气环流的气候异常特征。结果表明:97.9%的寒潮发生在11月至次年3月,且12月至次年2月频次最高。寒潮日数和频次呈现东高西低、北高南低的空间格局,而寒潮强度则中部最高、东部次之、西部最低。近61年寒潮站日数和站次数呈减少趋势,且桂北和桂东减少速率高于桂南和桂西,而站平均寒潮强度呈弱的增加趋势,增幅高值在中部和东部区域,但广西区域性的寒潮从日数、强度和覆盖的站点数量均没有显著变化。广西寒潮主要发生季的气温增加显著,且在1998年发生气温突变,气候变暖后,尽管寒潮频次下降,但区域性寒潮日数降幅较小,站点和区域寒潮强度均表现为轻微的增加趋势。南海副高位置偏南、北半球中高纬度极涡面积和强度指数偏大、乌拉尔山高压脊偏强、东亚大槽偏弱、北极涛动和北大西洋涛动为负位相时,造成广西寒潮频次偏多。

The study regarding the trend of low-temperature cold waves amid global warming represents a fundamental aspect of climate change research,offering important information for human production and life.Using daily average and minimum temperature records from 75 meteorological stations across Guangxi from 1961 to 2022,the occurrence,frequency,and severity of cold waves were analyzed based on established criteria for the region.Various statistical methods,including the WS2001 linear trend analysis,correlation,and composite analyses,were employed to study the climate change characteristics of cold waves and the corresponding atmospheric circulation in Guangxi.Results showed that 97.9%of cold waves occurred between November and March,peaking between December and February.The number of cold wave days and their frequency exhibited east-to-west and north-to-south decrements,respectively,while the intensity of cold waves was highest in central Guangxi,followed by the eastern region and then western regions.Over the past six decades,there has been a noticeable decrease in both the number of cold wave days at individual stations and their overall frequency.This decline was more pronounced in the northern and eastern parts of Guangxi compared to the southern and western areas.However,the average intensity of cold waves showed a marginal upward trend,particularly in the central and eastern regions.In terms of regional cold wave activity in Guangxi,there were no significant changes in the number of cold wave days,intensity,and the number of stations.The main cold wave season in Guangxi has experienced notable temperature increases,with a significant shift observed in 1998.Despite the reduction in cold wave frequency following global warming,the decrease in the number of cold wave days at a regional level was relatively small,and there was a slight increase in both station-specific and regional cold wave intensities.Furthermore,the study revealed that the cold wave frequency in Guangxi is higher when the northern boundary position of the South China Sea subtropical high lies to the south.Additionally,a greater vortex area and intensity index in the middle and high latitudes of the Northern Hemisphere,a stronger Ural high ridge,a weaker deep East Asian trough,and negative phases of the Arctic Oscillation and North Atlantic Oscillation contribute to increased cold wave activity.