ACP Atmospheric Chemistry and Physics ACP Atmos. Chem. Phys. 1680-7324 Copernicus Publications Göttingen, Germany 10.5194/acp-2-67-2002 Tropospheric NO<sub>2</sub> columns: a comparison between model and retrieved data from GOME measurements Lauer A. 1 Dameris M. 1 Richter A. 2 Burrows J. P. 2 DLR Institut für Physik der Atmosphäre, Oberpfaffenhofen, D-82234 Wessling, Germany Institut für Umweltphysik, Universität Bremen, D-28359 Bremen, Germany 19 04 2002 2 1 67 78 Copyright: © 2002 A. Lauer et al. 2002 This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 Generic License. To view a copy of this licence, visit https://creativecommons.org/licenses/by-nc-sa/2.5/ This article is available from https://acp.copernicus.org/articles/2/67/2002/acp-2-67-2002.html The full text article is available as a PDF file from https://acp.copernicus.org/articles/2/67/2002/acp-2-67-2002.pdf

Tropospheric NO<sub>2</sub> plays a variety of significant roles in atmospheric chemistry. In the troposphere it is one of the most significant precursors of photochemical ozone (O<sub>3</sub>) production and nitric acid (HNO<sub>3</sub>). In this study tropospheric NO<sub>2</sub> columns were calculated by the fully coupled chemistry-climate model ECHAM4.L39(DLR)/CHEM. These have been compared with tropospheric NO<sub>2</sub> columns, retrieved using the tropospheric excess method from measurements by the Global Ozone Monitoring Experiment (GOME) of up-welling earthshine radiance and the extraterrestrial irradiance. GOME is part of the core payload of the second European Research Satellite (ERS-2). For this study the first five years of GOME measurements have been used. The period of five years of observational data is sufficiently long to facilitate for the first time a comparison based on climatological averages with global coverage, focussing on the geographical distribution of the tropospheric NO<sub>2.</sub><br> <br> A new approach of analysing regional differences (i.e. on continental scales) by calculating individual averages for different environments provides more detailed information about specific NO<sub>x</sub> sources and of their seasonal variations. The results obtained enable the validity of the model NO<sub>2</sub> source distribution and the assumptions used to separate tropospheric and stratospheric parts of the NO<sub>2</sub> column amount from the satellite measurements to be investigated.