A Numerical Simulation Study Of A Deep Convection Weather Process And Its Effect On The Vertical Redistribution Of Pollutant Gases

Deep convective weather is a deeply developed convective weather system,which often leads to severe weather such as thunderstorms,strong winds,short-term heavy precipitation and hail,and it plays an important role in the vertical redistribution of atmospheric chemical gas components.In this paper,WRF-Chem,a mesoscale numerical model coupled with the chemical transmission model,combined with MEIC,an actual emission source information,was used to simulate a deep convective weather process in Guangdong on May 6,2016,in order to study the deep convection system and its influence on the vertical redistribution of atmospheric pollutants.This article uses the conventional surface observation meteorological data of the National Climate Data Center?NCDC?,the observation data of the high-density automatic observation station in Guangdong Province,and the radar data products provided by the Guangzhou SA-band Doppler radar to analyze the occurrence and development of this squall line weather process.An analysis was conducted to analyze the weather process from the perspective of the weather situation and unstable conditions.Use the ground pollutant data released by the National Urban Air Quality Real-Time Publishing Platform of China Environmental Monitoring Station to analyze the distribution characteristics of pollutants.The deep convective weather process is simulated by WRF.On the basis of obtaining a good simulation effect,the WRF-Chem is used to simulate the low solubility atmospheric pollutant gases such as CO,NO₂ and O₃ and the low solubility atmospheric pollutant gases such as SO₂?H₂O₂ and HNO₃ and other high-solubility atmospheric pollutant gases are removed to study the effect of deep convective weather systems on the redistribution of atmospheric chemical gas components in the actual atmospheric environment.The study found that CO gas has a significant accumulation near the ground in front of the convection system,and will be transported to the top of the troposphere and stratosphere with the ascending airflow,which significantly increases the concentration of CO gas in this area.There is also the same trend with NO₂ gas with low solubility.After the ascending cloud top enters the stratosphere,part of the O₃ gas entrained into the troposphere,causing the O₃concentration in the top of the troposphere to increase significantly.Due to the wet scavenging effect,the SO₂ gas will only be transported to a height of about 4km,and it has not significantly changed the distribution characteristics of the SO₂ gas concentration in the upper troposphere.Surface airflow advection convergence results in the high solubility of H₂O₂ near the ground,and the cloud particles sink and evaporate in the outflow area,causing the high-level H₂O₂ and HNO₃ enrichment areas to be located below the cloud anvil,while the troposphere and the bottom of the stratosphere appear.The entrainment phenomenon caused an increase in HNO₃concentration at the top of the troposphere.When the wet removal scheme is started,the removal efficiency of deep convection for CO is slightly greater than 0,and the removal efficiency for O₃ is negative.The removal efficiency of the remaining NO₂,SO₂,H₂O₂ and HNO₃ is 42.52%,68.12%,99.21%,and 22.8,respectively.%.After the wet removal scheme is closed,the removal efficiency of the medium and high solubility gases SO2,H₂O₂ and HNO₃ has decreased significantly.The study conclude that for the gas that is weakly dissolved in water,the physical transport of deep convection is more important,but for the medium and high solubility gas,the wet scavenging process greatly changes the vertical distribution of the gas and significantly reduces the Gas concentration in lower and upper layers.The wet scavenging process is an important process that affects the atmospheric removal of these pollutants,but it does not increase the removal efficiency as the solubility increases.Physical and chemical processes affect the atmospheric removal process of gas pollutants.