Analysis And Numerical Simulation Of Sea Fog In Shanghai Offshore

This paper analyzes the characteristics of sea fog and uses WRF(Weather Research and Forecasting Model)model and GSI assimilation system to carry out numerical simulation research on sea fog in Shanghai offshore area in recent years.The best configuration of the sea fog simulation model was explored,and the fine structure of the sea fog in Shanghai offshore was studied.Offshore Shanghai is a sea-fog-prone area.Visibility decreases when sea-fog occurs,which can easily lead to maritime transportation safety accidents.Due to the many factors affecting sea-fog,the process is non-adiabatic,which makes simulation difficult.This article first uses 2016-2018 site measured data,satellite data,and images to analyze the sea,fog,and year characteristics of the offshore sea fog in Shanghai.The relationship between various meteorological factors is compared with previous years to observe whether it has changed.It is found that the number of foggy days is decreasing year by year,but the seasonal changes and monthly changes are not much different from previous years.However,after statistical analysis of the measured data at each site,it is found that although the overall trend of each site is roughly the same,the details are not necessarily the same.For example,when the sea fog occurs at site A,the northeast wind is the main factor,and when the sea fog occurs at station C,the southeast direction is mostly Wind-based.Then,using the WRF model and the GSI assimilation system,a sensitivity experiment and a turbulent flow energy study of a parametric scheme on a case of Shanghai offshore sea fog on April 20,2016.In the past,numerical simulation research mostly focused on the Yellow and Bohai Seas,and research on parameterization schemes mostly focused on the configuration of boundary layer schemes and microphysical schemes.This article mainly studies how the configuration between the boundary layer scheme and the equally important long-wave radiation scheme is most suitable for this project.Numerical simulation of sub-sea fog.It was found that for this sea fog,the boundary layer scheme and the long-wave radiation scheme asked the YSU scheme and the CAM method respectively,and the effect of simulating the fog area was the best.In addition,through the study of turbulent flow energy,it was found that the turbulent flow energy was generally large during the sea fog process,but the reduction of turbulent flow energy in the early stage accelerated the zonal expansion of the sea fog.Finally,on April 20,2016,due to the large difference between the North and South Sea fog under the control of low pressure in Shanghai's offshore,this paper studies this fine process.Because there is not much research on the fine structure of sea fog in the past,especially in Shanghai area.Based on the weather situation,this article studied the weather elements,sea-air interface,and water vapor conditions at the time of the sea fog,and explored what caused the large variation in the north-south sea fog near the Yangtze River estuary near Shanghai.It was found that similar to other advection fogs,warm and humid air from the south coupled with cooling caused the occurrence of this sea fog,and the sudden change in low-pressure controlled wind direction affected the development and maintenance of sea fog.Therefore,it is necessary to study the fine structure of sea fog.In this paper,through the analysis of the characteristics of Shanghai coastal sea fog in recent years and numerical simulation studies,the trend of the coastal sea fog in Shanghai has been analyzed so far,and a parameterization scheme suitable for the numerical simulation of coastal sea fog in Shanghai has been explored.Sea fog forecasting provides some help.