Research And Application Of Ozone Retrieval Algorithm Based On The Multi-platform Differential Optical Absorption Spectroscopy

Ozone constitutes a vital trace gas within the Earth’s atmosphere,primarily concentrated in the stratosphere(approximately 90%).Stratospheric ozone serves as a barrier for the biosphere of the Earth,while in the tropospheric ozone,particularly in near-surface ozone,it assumes the role of a pollutant.The genesis of ozone,classified as a typical secondary pollutant,mainly arises from photochemical reactions between NOx and volatile organic compounds(VOCs).Recently,the concentration levels of major air pollutants(sulfur dioxide,nitrogen dioxide,and PM2.5)have exhibited an overall downward trajectory in China.However,the issue of ozone pollution has witnessed a mounting prominence,emerging as the primary pollutant in numerous urban centers across China.Therefore,ozone monitoring needs to be put on the agenda.The measurements of near-surface and regional ozone distribution assume paramount significance in the context of ozone monitoring.The monitoring of the tropospheric ozone profiles can not only elucidate the variations of surface ozone,but also provide insights into the distribution and vertical transmission characteristics of ozone pollution on the vertical scale,which is the basis for analyzing the formation mechanism of ozone pollution.Given the recurrent occurrences of transregional ozone pollution transmission events,monitoring regional ozone pollution assumes pivotal importance.Satellite-based measurements are critical in facilitating the monitoring of large-scale regional ozone.Differential optical absorption spectroscopy(DOAS)technique can monitor columns and non-blind zone profiles of trace gases,which provides strong support for analyzing the formation mechanism of tropospheric ozone and monitoring regional ozone.Therefore,by leveraging the DOAS technique,the retrievals of tropospheric ozone profiles from ground-based multi-axis differential optical absorption spectroscopy(MAX-DOAS)instrument and total ozone columns from environmental trace gases monitoring instrument(EMI)were studied in this dissertation.The main conclusions are as follows:1.The difficulty for obtaining the tropospheric ozone profiles with MAX-DO AS measurements lies in the interference caused by stratospheric ozone absorption.To solve this problem,the stratospheric ozone differential slant column density(DSCD)was simulated in SCIATRAN model with the stratospheric ozone profiles from microwave limb sounder(MLS)as the input.The "time-interpolated zenith spectrum"is innovatively used as the reference spectrum during the spectral fitting to obtain the relatively "clean" tropospheric ozone DSCD.The calculated tropospheric ozone DSCD is used as the input of forward model to retrieve the non-blind zone tropospheric ozone profiles.2.The tropospheric ozone profile retrieval algorithum was applied to the joint observation experiment in the Great Bay Area(GBA)region,and the retrieved results were compared with that from the ozone lidar and near-surface in-situ measurements,and the results have good correlation.Compared with lidar results,the relative differences between 300 and 800 meters near the surface are less than 15%.Compared with near-surface in-situ measurements,the correlation coefficients(R)are 0.75 and 0.81,respectively.Based on tropospheric ozone and its precursor profiles retrieved by MAX-DO AS measurements,the threshold interval of ozone formation types sensitivity in the boundary layer of GBA region was constructed,and the formation mechanism of ozone pollution in the boundary layer in the GBA region was analyzed.The results show that the formation of boundary layer ozone in Guangzhou and Heshan is dominated by VOCs and NOx,respectively.3.The total ozone columns were retrieved using the level 1 spectral data from the first Chinese hyper-spectral satellite-based air pollution load(EMI).The principal component analysis(PCA)method was used to subtract the residual spectral structure when retrieving the slant column density(SCD).The iterative air mass factor(AMF)calculation scheme reducing the retrieval error from a priori profiles and de-stripe method using the Fourier transform were used to retrieve the accurate total ozone columns of EMI.The retrieved total ozone columns were validated in comparison with OMI,TROPOMI,and ground-based measurements,with the averaged differences less than 5%.In addition,the tropospheric ozone columns during summer in China were obtained by coupling the stratospheric ozone profiles from the MLS measurements.In summary,based on the multiple-platform DOAS technique,the retrieval of nonblind zone tropospheric ozone profiles and regional ozone concentrations were achieved in this dissertation,which provides a reliable means for ozone monitoring.