Investigation of SO₂Effect on TOMS O₃Retrieval from OMI Measurement in China

Abstract

:In this present study, we identified the SO2 effect on O3 retrieval from the Ozone Monitoring Instrument (OMI) measurement over Chinese Industrial region from 2005 through 2007. The Planetary boundary layer (PBL) SO2 data measured by OMI sensor is used in this present study. OMI-Total Ozone Mapping Spectrometer (TOMS) total O3 is compared with OMI-Differential Optical Absorption Spectrometer (DOAS) total O3 in various SO2 condition in PBL. The difference between OMI-TOMS and OMI-DOAS total O3 (T-D) shows dependency on SO2 (R (Correlation coefficient) = 0.36). Since aerosol has been reported to cause uncertainty of both OMI-TOMS and OMI-DOAS total O3 retrieval, the aerosol effect on relationship between PBL SO2 and T-D is investigated with changing Aerosol Optical Depth (AOD). There is negligible aerosol effect on the relationship showing similar slope (1.83 ≤ slope ≤ 2.36) between PBL SO2 and T-D in various AOD conditions. We also found that the rate of change in T-D per 1.0 DU change in PBL, middle troposphere (TRM), and upper troposphere and stratosphere (STL) are 1.6 DU, 3.9 DU and 4.9 DU, respectively. It shows that the altitude where SO2 exist can affect the value of T-D, which could be due to reduced absolute radiance sensitivity in the boundary layer at 317.5 nm which is used to retrieve OMI-TOMS ozone in boundary layer.