Characteristics of Atmospheric Mixing Layer Height and Its Relationship with PM2.5 Concentration in Sichuan Basin
The maximum mixed height(MMH)of three representative stations(Chengdu,Yibin,and Dazhou)in Sichuan Basin is estimated using the sounding data from 2016 to 2018.ERA-interim re-analysis data of boundary layer height(ERA-PBLH)is used to evaluate the reliability of MMH.The probability distribution,seasonal variation characteristics of MMH analyzed.Based on the PM2.5 average concentration data and surface meteorological observation data,the relationship between MMH,as well as other meteorological factors and PM2.5 daily average concentration is analyzed.The results show that the MMH in Sichuan Basin is generally low.In seasonal distribution,the MMH is the highest in spring and lowest in autumn in Chengdu and Yibin,while highest in summer and lowest in winter in Dazhou.The main reasons for this regional difference are the seasonal variations of sensible heat fluxes and water vapor conditions.On the whole,the average PM2.5 concentration decreases gradually with the increase of MMH.Heavy polluted weather mostly occurs under the condition of lower MMH and larger relative hu-midity.The lower lifting condensation level limits the increase of mixing layer height.The aerosol hygro-scopic growth is obvious,and the pollutants are easy to accumulate.The high PM2.5 concentration in ba-sin usually occurs in the wind speed of about 1.0 m/s,and the air inflow in the basin has an obvious in-creasing effect on the local pollutant concentration.
maximum mixing height(MMH)characteristics analysisPM2.5meteorological factor
NETL
NSTL
万方数据
