西南地区秋冬雾日年际与年代际变化的对比研究  

Comparative Analysis on Interannual and Interdecadal Changes of Fog Days in Autumn and Winter of Southwest

作　　者：张颖[1] 刘鹏[1] ZHANG Ying;LIU Peng(Key Laboratory of Meteorological Disaster,Ministry of Education/Joint International Research Laboratory of Climate and Environment Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters,Nanjing University of Information Science and Technology,Nanjing 210044)

机构地区：[1]南京信息工程大学气象灾害教育部重点实验室/气候与环境变化国际合作联合实验室/气象灾害预报预警与评估协同创新中心,南京210044

出　　处：《气候与环境研究》2023年第4期343-355,共13页Climatic and Environmental Research

基　　金：国家重点研发计划2016YFA0600402。

摘　　要：利用1958~2007年503个中国地面观测站点的雾日数资料,分析了全国秋冬雾日数的时空特征。结果表明,西南地区在秋冬发生雾日频率较高,达到了18 d以上,是中国东部地区同期雾日数的2倍以上。西南地区秋冬雾日存在显著的年际和年代际尺度气候变率。在两个时间尺度上,发生雾日的气象条件存在显著差异。在年际尺度上,西南地区中高层北风异常较为显著,因而将北方的冷空气带到西南地区,使得西南地区中高层出现了显著的冷空气异常。由于该地区处于雨带的北侧,存在一定的温湿空气,上空伴随着异常下沉运动,将高层的冷空气带到低层,而此时低层大气的温度、湿度异常偏高,冷暖空气汇合,容易过饱和,所以雾日偏多。在年代际尺度上,西南地区低层异常北风相比于年际尺度更为显著,因而低层北方冷空气的南下,使西南地区出现显著的降温降湿,但是温度下降速率快于湿度下降速率,所以温度露点差为负,空气容易达到饱和,伴随大气较为稳定,导致雾日偏多。Based on the 503 observed fog station data from 1958 to 2007,the temporal and spatial characteristics of fog days in autumn and winter were analyzed.It was found that the fog in autumn and winter occurs frequently over Southwest China.The annual average number of fog days in autumn and winter in Southwest China is more than 18 days,which is twice as many as that in eastern China in the same period.Moreover,there is a significant climate variability of fog days in autumn and winter in Southwest China,which is mainly reflected in the interannual and interdecadal scales,and there are significant differences in the meteorological conditions of fog days in different climate scales.On the interannual scale,the north wind anomaly in the middle and upper levels is more significant,which brings the cold air from the north to the southwest,causing the cold air anomaly in the middle and upper levels over the southwest.Moreover,due to the strong sinking movement over the region,the cold air in the upper levels is brought to the lower levels.At this time,because of the abnormally high temperature and humidity in the lower levels,the cold and warm air converges over Southwest China which is located in the north of the rain belt.In a result,the air is easily oversaturated,resulting the number of fog days increasing.On the interdecadal scale,the anomalous northerly wind in the lower level is more significant compared with the interannual scale,which brings the cold air in the lower level from the north to the southwest.This results in the decreasing of temperature,specific humidity and temperature dew point difference and further leads to the supersaturation of water vapor in the Southwest China because the temperature drops faster than the humidity.At the same time,the atmosphere is relatively stable,increasing the number of fog days.

关 键 词：西南地区 秋冬雾日 年际 年代际 水汽条件 

分 类 号：P467[天文地球—大气科学及气象学]