Study on a Large-Scale Persistent Strong Dense Fog Event in Central and Eastern China

Hongbin Wang,Zhiwei Zhang,Yuying Zhu,Duanyang Liu,Chengsong Yuan,Xuerong Zhang

doi:10.1155/2020/8872334

Abstract

A large-scale persistent strong dense fog (SDF) event that occurred from December 30, 2016, to January 5, 2017, in central and eastern China is analyzed by using a variety of data, including high-resolution satellite and surface observations, meteorological tower observations, fine-resolution sounding observations, and NCEP/NCAR reanalysis data. The results show the following: (1) The SDF event has the characteristics of long duration, wide influence range, large intensity, and serious air pollution. During the study period, there are 531 stations with SDF events, covering an area of over 360,000 km2. There were five stations in Hebei province where the fog lasted for more than 77 hours, and even some stations did not dissipate during the day. (2) Radiation fog and advection fog alternate in this SDF event, namely, radiation fog (20:00 BT on December 30 to 14:00 on January 1), advection radiation fog (20:00 on January 1 to 08:00 on January 2), radiation fog (night on January 2 to daytime on January 3), and advection radiation fog (night on January 3 to January 5). The characteristic of radiation fog is that the central and eastern part of China was controlled by “L” type high pressure. In the stage of advection radiation fog, the combined effect of weak cold advection and radiation cooling leads to the occurrence of SDF. (3) Regarding the duration of the fog event, the inversion structure is continuously maintained at night and in the morning near the stratum, and when the fog intensity is strong, the inversion intensity is correspondingly large, the fog top is lower than the inversion layer top, and the top of the SDF is between 80 and 400 meters.

Highlights

Fog is a suspension of very small, usually microscopic water droplets in the air, reducing visibility at the Earth’s surface
In the stage of advection radiation fog, the combined effect of weak cold advection and radiation cooling leads to the occurrence of strong dense fog (SDF). (3) Regarding the duration of the fog event, the inversion structure is continuously maintained at night and in the morning near the stratum, and when the fog intensity is strong, the inversion intensity is correspondingly large, the fog top is lower than the inversion layer top, and the top of the SDF is between 80 and 400 meters
A dense fog (DF) event reduces visibility to 500−200 m, a strong dense fog (SDF) event reduces visibility to 200−50 m, and an extremely dense fog (EDF) event reduces visibility below 50 m. e fog has a serious impact on sea, land, and air transportation, especially the SDF with visibility less than 200 m, which often results in the shutdown of the freeway, taking off and landing difficulty of airplanes, and suspension of sea transportation

Summary

Introduction

Fog is a suspension of very small, usually microscopic water droplets in the air, reducing visibility at the Earth’s surface. Wu et al [36] analyzed the water vapor transport and the inverse temperature characteristics of a continuous dense fog event in south-central of North of China during February 13-14, 2006. E existing studies are mainly focused on the analysis of the thermal, dynamic, and water vapor conditions of the regional persistent fog process, but few studies have been done on the horizontal distribution of persistent SDF and the evolution characteristics of the vertical structure across the region combined with vertical observation data. Based on the high-resolution satellite and ground observation data, Tianjin 255 m meteorological tower data, multistation second-level sounding data, and NCEP/ NCAR 1° × 1° reanalysis data, we analyze and study the large range strong dense fog process before January 5, 2017, in this paper.

Stations and Data

Results and Discussion

Conclusions