Validation of the IUP Bremen TROPOMI tropospheric VC NO2 product and comparison to the operational TROPOMI product

As part of the German integrated greenhouse gas monitoring project (ITMS), an improved TROPOMI NO₂ product has been created, called the IUP Bremen TROPOMI product. TROPOMI NO₂ slant column data and recalculated air mass factor (AMF) are used to derive tropospheric NO₂ vertical columns over Europe. The recalculated AMF uses temporally and spatially higher resolved a priori NO₂ profiles, obtained from the regional CAMS ensemble, and surface reflectances from the moderate-resolution Imaging Spectroradiometer (MODIS) database, using the bi-directional reflectance distribution function (BRDF) data. In this study, the newly calculated tropospheric NO₂ vertical columns are compared to the operational TROPOMI product and to retrievals using other a priori profiles and surface reflectance data. In a next step, a validation of the IUP Bremen TROPOMI data product using MAX-DOAS data from the FRM4DOAS project is conducted. The validation shows improved statistics, finding a slope of 0.90, which is a 50% increase compared to the operational product and a reduced scatter of the data. In a last step, the influence of the near-real-time cloud data compared to the reprocessed cloud data on the retrieval is investigated. 

 

Acknowledgements:

We acknowledge the use of FRM4DOAS MAX-DOAS data produced at BIRA using data from instruments operated by the BIRA, KNMI, University of Bremen, University of Heidelberg, University of Thessaloniki, MPIC and CNR.