A Downscaling Study Of The Effects Of Climate Change On Stationary Weather And Air Quality In My Country

In recent years,air pollution emission sources have been controlled,but pollution events still occur in various places in China.Studies have shown that heavy air pollution events are usually closely related to air stagnation.At present,many scholars have proposed air stagnation index that can evaluate air pollution.In this study,the climate data of the CESM model under the three RCP scenarios(RCP4.5,RCP6.0,RCP8.5)provided by CMIP5 are used as the initial boundary conditions to drive the WRF.Therefore,the dynamic downscaling method is used to simulate the future climate change in winter and summer in China,and to explore the impact of climate change on air stagnation.Fixed emissions,using the climate data obtained by the WRF model under different scenarios as the meteorological input,using the CMAQ model to simulate the PM_2.5 and O₃ concentration data,and directly obtaining the impact of climate change on air quality,and test the correlation between air stagnation and air quality This will lead to a better understanding of the links between climate change,air stagnation,and air pollution,which has important practical significance for decision makers to better formulate relevant plan.The research shows:(1)The results of WRF downscaling simulation of boundary layer height,precipitation,wind speed and temperature are generally in line with the reference values,and the simulation results of wind and temperature are the best.The CMAQ simulation results of PM_2.5 are numerically overestimated overall,the 8-hour maximum ozone is overestimated for low values,and high values are underestimated.(2)In the middle of this century,the average frequency of air stagnation showed a decreasing trend in winter in China.This decreasing trend is mainly caused by the reduction of moderate air stagnation events.The long-lasting severe air stagnation events and extreme air stagnation events show a large-scale increase trend.The air stagnation tends to change to extremes in the future.(3)Air stagnation has a good indication effect on PM_2.5.Affected by the decrease in the average air stagnation,the PM_2.5 concentration and extreme value in winter will decline in the middle of this century.The PM_2.5 exceeding day will have the largest decline in the RCP6.0scenario,and the largest decline in space in central and eastern China.However,due to the large-scale increase in the frequency of severe and extreme air stagnation events in the future winter,attention should still be paid to the control of emission sources.(4)Under the RCP4.5 and RCP8.5 scenarios,the summer O₃ showed an upward trend in the middle of this century,with larger increases in North China,East China,and Central China.The applicability of O₃ in air stagnation is poor,but it still has good applicability in East China,Central China and Southwest China.