Retrieval Of Aerosol Profile,Tropospheric NO₂ And HCHO VCD Using MAX-DOAS Technique In Shanghai

In this paper,we report on the retrieval of aerosol extinction profiles,NO₂ and HCHO tropospheric vertical column concentration using multi-axis differential absorption spectroscopy?MAX-DOAS?over 9 cloud-free day time period?July 28 to August 5,2015?in Shanghai.And the inversion results are compared with satellite products.In the inversion process,firstly,we use QDOAS software to obtain differential slant column concentration of O₄,NO₂ and HCHO.And the absorption bands adopted by them are337³70nm,411⁴35nm,336³59nm,respectively.Meanwhile,weconsiderthe contribution of various absorbents and Ring effect to the measured spectrum.Then the radiation transmission mode SCIATRAN was rationally allocated by usingIGRA temperature and pressure sounding profile to correct the mode configuration.Then did the geometry-sensitivity experiments of O₄AMF and a consistancy check of O₄DSCD,geting a correction factor of 1.5.The aerosol extinction coefficient?550nm?was inverted by the check table method,and the aerosol increased in the afternoon in the 9days.The retrieval of NO₂ and HCHO tropospheric vertical column concentration using the two-step method,taking the aerosol information retrieved to the trace gas inversion process.According to the inversion result,the diurnal variation of NO₂ tropospheric vertical column concentration is mainly characterized by bimodal characteristics,reaching the minimum at noon due to the solar radiation and reaching the maximum at traffic peak periods.The HCHO tropospheric vertical column concentration shows a weaker monomodal pattern feature with the changes of solar radiation..Comparing the NO₂ and HCHO tropospheric vertical column concentration retrieved by MAX-DOAS technology with the GOME-2 and OMI satellite products,we can found that inversion results higher than satellite products.Among them,the ratios of retrieved NO₂ tropospheric vertical column concentration to seven satellite products are between 1.5 and 3.1,and the ratios of retrieved HCHO tropospheric vertical column concentration to three satellite products are between 1.2 and 2.1.And the correlation coefficient between retrieved NO₂ tropospheric vertical column concentration and GOME-2/MetOp-B/TEMIS products was 0.8388,and the correlation coefficient between retrieved HCHO tropospheric vertical column concentration and OMI/TEMIS products was 0.7825.Finally,using the ratio of retrieved HCHO to NO₂ tropospheric vertical column concentration can conclude that the chemical sensitivity of local ozone production have obvious daily changes,which is VOCs controld-VOCs-NO_x controld-NO_x controld-VOCs-NO_x controld-VOCs controld.