| Atmospheric aerosol is a colloidal multiphase system consisting of liquid or solid particles suspended in the atmosphere.Its diameter ranges from a few nanometers to tens of micrometers.Aerosol has direct impact on air quality,atmospheric radiation,global climate change,and human health.In recent years,severe haze pollution has frequently occurred in Beijing-Tianjin-Hebei region,Fenwei Plain,Yangtze River Delta and other industrially developed and densely populated urban agglomerations.Atmospheric aerosols are the main component of haze.The detection of the vertical distribution of atmospheric aerosols has great significance for studying the causes of haze.At present,the technology for detecting the vertical distribution of atmospheric aerosols is mainly based on lidar,air sounding balloons,and unmanned aerial vehicles(UAV),which have a wide range of applications.However,Lidar has problems such as high cost and blind spots near the ground.At the same time,air sounding balloons and UAV also have problems that cannot be observed for a long time.Multi-axis differential absorption spectroscopy technology(MAX-DOAS)is a kind of atmospheric remote sensing technology beased on ultraviolet-visible spectrum,which has the characteristics of stability and real-time continuous monitoring.It can obtain arosol optical dopth(AOD)and the vertical distribution information of aerosol extinction at the same time,which become is a powerful technology on vertical aerosol detection.Aiming at the demand for high-precision vertical distribution detection of atmospheric particulate matter under heavy pollution conditions,this paper conducted a MAX-DOAS-based aerosol vertical distribution feature detection technology research.The focus was on the aerosol inversion method based on the optimal estimation method driven by the look-up table method,the conversion method of aerosol extinction coefficient and the mass concentration of particulate matter,the spatial-temporal distribution and transportation of aerosol and trace gas in typical areas,and aerosol characteristics and pollution sources in the period of heavy pollution.Aiming at the problem that the accurate retrieve of aerosols in China under heavy pollution conditions is easily affected by the prior profile,the MAX-DOAS aerosol retrieve method based on the optimal estimation method driven by the look-up table method was carried out for the first time.The look-up table of atmospheric parameters in typical regions of China was established,suitable prior profiles were screened by Monte Carlo method.And aerosol extinction profile was retrieved by substituting the optimal estimation method.Through model simulation and field experiments,the aerosol profiles retrieved under different AOD conditions were compared,and the influence of different prior profiles on the aerosol profile retrieval was analyzed,and the optimal estimation method driven by the look-up table method was verified.Accuracy of aerosol retrieval under heavy pollution conditions.Aiming at the problem of PM2.5 vertical distribution detection and transportation,the conversion method of aerosol extinction coefficient and particle mass concentration under different humidity classifications was studied.The conversion method is optimized by adding the water vapor profile parameters retrieved by MAX-DOAS.The results of comparison with different instruments show that the correlation R between the PM2.5 retrieved by MAX-DOAS and the PM2.5 measured by different instruments is greater than 0.89,which verified the reliability of the conversion method and realized that the detection of the PM2.5 mass concentration vertical distributed by MAX-DOAS.In typical areas(coastal and inland Fenwei plains)of China,applied research on the conversion method of aerosol extinction coefficient and particulate matter concentration under different humidity classifications was carried out,and the vertical distribution characteristics of aerosols were obtained.The results showed that the vertical distribution of aerosols in the eastern coastal areas was Gaussian,with a maximum extinction height of 200 to 400 m.It has obvious seasonal transport characteristics between land and sea.The vertical distribution of aerosol in the Fenwei plain in the inland area was Gaussian or Boltzmann type.The maximum transport flux height of PM2.5 was 800 m,and the transport fluxs under the northeast wind were largest.In this paper,the accuracy of aerosol retrieval by MAX-DOAS in high aerosol state was improved.Combined with relative humidity data,the vertical distribution detection of PM2.5 by MAX-DOAS was realized.Those have great significance for research of the spatial and temporal distribution of aerosols,pollution evolution and regional transportation.Furthermore,effective and reliable data support weve provided for model verification. |
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