Study On The Tropospheric Ozone Column Retrieval And Validation In China

Ozone is one of significant trace gases in the atmosphere,with both chemical and radiative active characteristics,it directly affects global climate change and the Earth’s environment.Tropospheric ozone,only accounting for 10% of the total amount,plays a key role in the atmosphere,this paper focus on the ozone retrieval and evolution in China region.Firstly,two total ozone column products from OMI were compared,then three retrieval methods,residual method,line-shape method,cloud method,were applied to China to derived the tropospheric ozone column(TOC),and the result shows that residual method with OMI-MLS is the best for the inversion in China.Finally,the spatial and temporal characteristics and long-term variation trend of TOC in China region from 2005 to 2016 were analyzed.Meanwhile,TOC was compared to near-surface ozone.1)There are two total ozone products of OMI,OMI TOMS and OMI DOAS,and the result shows that the two have good consistency.Cloud adds to the differences between the two products.In the presence of clouds,the difference increases with the solar zenith angle.Pixel position,stratospheric SO2,aerosol have no obvious influence on the difference between the two products.2)Three retrieval methods,residual method,line-shape method,cloud method,were used to derive TOC in China,only OMI-MLS by residual method and line-shape method were suitable to get the TOC map of China.Validation results show that OMI-MLS is most suitable for the inversion of TOC in China.3)OMPS,with both limb mode and nadir mode,was considered to be applied to residual method,however tropopause in China usually can not be detected by the limb profile.Cloud method was conducted by Cloud-Slicing correlation on the basis of CCD(Convective-Cloud Differential),but the result is only reasonable in summer time.This may attribute to the seasonal characteristic of cloud properties.4)Based on the satellite-retrieval results,during the past 12 years,the content of tropospheric ozone column in China has been increasing year by year.Serious pollution occurs in eastern China and Sichuan Basin,and the highest pollution level was in Beijing-Tianjin-Hebei during summer.Tropospheric ozone is highly correlated with near-surface ozone in most areas of China.