ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-6-1075-2006 Estimating the NO<sub>x</sub> produced by lightning from GOME and NLDN data: a case study in the Gulf of Mexico Beirle S. 1 Spichtinger N. 2 Stohl A. 3 Cummins K. L. 4 Turner T. 4 Boccippio D. 5 Cooper O. R. 6 Wenig M. 7 Grzegorski M. 1 Platt U. 1 Wagner T. 1 Institut für Umweltphysik, Universität Heidelberg, Germany Department of Ecology, Technical University of Munich, Germany Norsk institutt for luftforskning NILU, Kjeller, Norway Vaisala, Tucson, Arizona, USA Global Hydrology and Climate Center, NASA Marshall Space Flight Center, Huntsville, Alabama, USA NOAA Aeronomy Laboratory, Boulder, Colorado, USA NASA Goddard Space Flight Center, Greenbelt, Maryland, USA 03 04 2006 6 4 1075 1089 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/6/1075/2006/acp-6-1075-2006.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/6/1075/2006/acp-6-1075-2006.pdf

Nitrogen oxides (NO<sub>x</sub>NO+NO<sub>2</sub>) play an important role in tropospheric chemistry, in particular in catalytic ozone production. Lightning provides a natural source of nitrogen oxides, dominating the production in the tropical upper troposphere, with strong impact on tropospheric ozone and the atmosphere's oxidizing capacity. Recent estimates of lightning produced NO<sub>x</sub> (LNO<sub>x</sub>) are of the order of 5 Tg [N] per year with still high uncertainties in the range of one order of magnitude. <P style="line-height: 20px;"> The Global Ozone Monitoring Experiment (GOME) on board the ESA-satellite ERS-2 allows the retrieval of tropospheric column densities of NO<sub>2</sub> on a global scale. Here we present the GOME NO<sub>2</sub> measurement directly over a large convective system over the Gulf of Mexico. Simultaneously, cloud-to-ground (CG) flashes are counted by the U.S.&nbsp;National Lightning Detection Network (NLDN<SUP><SMALL>TM</SMALL></SUP>), and extrapolated to include intra-cloud (IC)+CG flashes based on a climatological IC:CG ratio derived from NASA's space-based lightning sensors. A series of 14&nbsp;GOME pixels shows largely enhanced column densities over thick and high clouds, coinciding with strong lightning activity. The enhancements can not be explained by transport of anthropogenic NO<sub>x</sub> and must be due to fresh production of LNO<sub>x</sub>. A quantitative analysis, accounting in particular for the visibility of LNO<sub>x</sub> from satellite, yields a LNO<sub>x</sub> production of 90 (32-240) moles of NO<sub>x</sub>, or 1.3 (0.4-3.4) kg [N], per flash. If simply extrapolated, this corresponds to a global LNO<sub>x</sub> production of 1.7 (0.6-4.7)Tg [N]/yr.