主办单位:中国气象局沈阳大气环境研究所
国际刊号:ISSN 1673-503X
国内刊号:CN 21-1531/P

Journal of Meteorology and Environment ›› 2024, Vol. 40 ›› Issue (1): 79-87.doi: 10.3969/j.issn.1673-503X.2024.01.010

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The impact of winter sea surface temperature change in the central eastern tropical Pacific on the number of heavy fog days in Guangxi

Hao QIN1(),Fengqin ZHENG2,*(),Chongzhi SUN3   

  1. 1. Guangxi Zhuang Autonomous Region Meteorological Observatory, Nanning 530022, China
    2. Guangxi Zhuang Autonomous Region Climate Center, Nanning 530022, China
    3. Guangxi Zhuang Autonomous Region Meteorological Service Center, Nanning 530022, China
  • Received:2023-08-22 Online:2024-02-28 Published:2024-03-25
  • Contact: Fengqin ZHENG E-mail:289055112@qq.com;zhengfengq@sohu.com

Abstract:

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, weakening 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 around 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. Furthermore, 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 absolute 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, ultimately 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.

Key words: Sea surface temperature, Abnormal anticyclonic, Stratification stability

CLC Number: