Research On Multi-layer Inversion And Its Environmental Effects In Chengdu Area

As is known to all,Chengdu area is not only the economic center of Sichuan basin,but also the prone and high incidence area of haze.Looking at the systematic cognition of the vertical thermal structure and the vertical distribution of particulate matter in sichuan basin.through the integration of multiple data and the application of multiple methods,An innovative algorithm to inverse the Logistic profile of atmospheric extinction coefficient is constructed,this paper carried out a systematic study on multi-layer temperature inversion and its environmental effects in Chengdu.The achievement of the research will provide scientific foundations for air pollution potential forecasting,improvement of boundary layer model and atmospheric environmental management in autumn and winter in Sichuan basin.The main conclusions are as follows:(1)the frequency distribution characteristics of temperature inversion in Chengduarea were analyzed using the daily sounding data of wenjiang upper air stationat 8:00 and 20:00 from 2013 to 2017.It was found that the temperatureinversion layer in Chengdu area is mainly divided into three layers,namely theinversion of near stratum?the inversion in the top of Atmospheric boundarylayer and the inversion of upper layer.Focusing on the frequency,intensity,bottom height,top height,thickness and generation and dissipationcharacteristics of the inversion of near stratum.The results show that theinversion of near stratum in Chengdu area has the highest frequency and thestrongest intensity.There are significant seasonal and diurnal variations in theinversion of near stratum,and its generation and dissipation are mainly affectedby the diurnal variations of solar radiation.Furthermore,similar studies on theother two inversion layers are carried out to systematically reveal the evolutionlaw of multi-level inversion structures in chengdu area.(2)Using the Mie scattering laser radar data,the multi-channel microwave radiationdata of RPG-HATPRO foundation?the near-surface fine particulate matter andconventional metrological observations in Chengdu from December 2016 toJanuary 2017,It was found that the inversion of near stratum is very importantfor the accumulation of particulate matter.In this study,a new method tocalculate the parameters of Logistic profile model of atmospheric extinctioncoefficient was proposed.This method was based on the preliminary researchof Logistic curve to simulate atmospheric extinction coefficient profile,andcombined with atmosphere optical depth(AOD)data from the solar photometer(CE-318)as well as ground visibility data.The application results using the datafrom June 2013 to May 2014 in Chengdu showed that:Under continuouslystable conditions,simulated results obtained by the former were obviouslybetter than those of the latter.Further analysis indicated that the applicability ofLogistic vertical distribution model mainly lied in its excellent ability tosimulate the complex vertical forms of atmospheric extinction coefficient innear surface layer.(3)Using the data of the sounding data of wenjiang upper air station from 2013 to2017 and atmospheric extinction coefficient detected by Mie scattering lidarfrom June 2013 to May 2015 of Chengdu,based on the sigmoid algorithm ofatmospheric extinction coefficient contour shape were analyzed,whats more.using the sounding data further to discuss the relationship between inversionand particulate matter structure characteristic.It is concluded that there is atransition zone between the particle extinction and molecular extinction near theatmospheric boundary layer,and it presents an S-shaped morphological feature.In addition,the existence of inversion at the top of the atmospheric boundarylayer inhibits the vertical diffusion of particulate matter,which is one of theimportant causes for the formation of the transition zone of the boundary layer.