The impact of winter sea surface temperature change in the central eastern tropical Pacific on the number of heavy fog days in Guangxi
Using daily heavy fog data from 80 stations in Guangxi from 1979 to 2020,sea surface temperature data from the Hadley Centre,and NCEP/NCAR reanalysis data,and employing correlation analysis,composite analysis,and information flow causality theory,this study analyzed the impact of winter sea surface temperature change in the central eastern tropical Pacific on the number of heavy fog days in Guangxi.The results show that the winter sea surface temperature in the central eastern tropical Pacific is a significant source of influence on the number of fog days in Guangxi,with higher(lower)temperatures contributing to more(fewer)heavy fog events in winter.Higher sea surface temperature in the central eastern tropical Pacific causes abnormal rising motions aloft,weake-ning the Walker Circulation and leading to abnormal descending motions over the tropical western Pacific,resulting in locally negative heating anomalies,and in turn triggering anomalous anticyclones in the lower troposphere a-round the Philippines to the north of the tropical western Pacific.Under the influence of the southwest winds on the northwest side of the anomalous anticyclone over the Philippines,Guangxi experiences a dynamic reduction in near-surface northerly winter monsoon wind speed,favoring the formation and maintenance of heavy fog.Further-more,this situation makes a significant anomalous anticyclonic moisture circulation from the South China Sea to the northwest Pacific maintained,facilitating the transportation of moisture from the South China Sea to southern China,which enhances the entire atmospheric column's moisture flux convergence over Guangxi,increases the ab-solute humidity in the lower troposphere,and generates gradually saturated the water vapor near the surface,and then enhances the stability of the near-surface layer,and provides favorable conditions for heavy fog formation,ul-timately leads to an increase in foggy days.Conversely,lower winter sea surface temperatures in the central eastern tropical Pacific generally leads to the opposite situation i.e.fewer heavy fog events in Guangxi.
万方数据
维普
