中国不同区域气候条件对冬季雾日形成的差异性分析

Analysis of Variations of Winter Fog Days Formation across Different Regional Climatic Conditions in China

雾是一种严重的天气灾害,极大地影响了交通和日常生活,并可能带来巨大的经济损失。利用1958~2007年678个中国地面观测站点的雾日数资料,采用相关系数分析、合成分析等方法分析了冬季雾日数的时空特征,发现冬季多雾地区和年际变率较强地区集中在西南、华北和华南等地区。根据冬季雾日分布特征,将中国划分为3个较为独立的雾区,从水汽条件、大气稳定度及大气环流背景等方面讨论了区域气候条件差异对局地雾形成机制的影响,发现不同区域冬季雾日产生的气候条件有着明显的差异性。结论如下:西南区冬季雾的形成受水汽输送影响较小,受大气稳定度影响较大,且巴尔喀什湖东侧高压脊加强,冷空气南下,西南较易发生雾;华北冬季雾日的形成受水汽输送影响较大,伴随长江中下游水汽异常推进偏北,水汽异常大值中心偏北,且西伯利亚高压、东亚大槽以及东北低压减弱,冷空气活动较弱,华北较易发生雾。华南冬季雾日的形成受水汽输送影响较大,伴随长江中下游水汽异常推进偏弱,水汽异常大值中心偏南,且东亚大槽减弱,华南较易发生雾。

Fog is a severe weather hazard that greatly influences traffic and daily life,potentially contributing to heavy economic losses.Based on the observed fog data from 1958 to 2007,using correlation coefficient analysis and composite analysis,the temporal and spatial characteristics of fog days in winter were analyzed.It was found that fog in winter frequently occurred,and the interannual variability in winter fog days was relatively strong,mainly over southwestern China,northern China,and Fujian.According to the distribution patterns of the winter fog days,we defined three relatively independent fog areas.The influence of regional climatic conditions on local fog formation mechanisms is discussed from the aspects of water vapor transport,atmospheric stability,and atmospheric circulation.There was a significant difference in climatic conditions for winter fog formation among the different regions.Winter fog formation over southwestern China was less affected by water vapor transport,while more affected by the atmospheric stability and the southward cold air.Winter fog formation over northern China was affected by water vapor transport;they occurred more frequently when water vapor was transported farther north and convective instability occurred over the middle and lower Yangtze River.Meanwhile,the formation and maintenance of winter fog days over southern China were also found to be influenced by vapor transport;when water vapor was transported farther south,the fog occurred more frequently.In terms of atmospheric circulation,winter fog formation was mainly affected by the deepening high-pressure ridge,east of the Balkhash Lake over southwestern China,weakening of East Asia trough and Siberian High over northern China,and the weakening of the Siberian High over southern China.