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UP: Umweltphysik
UP 23: Atmosph
äre und Klima
UP 23.4: Fachvortrag
Wednesday, March 15, 2006, 17:15–17:30, D
Estimating the NOx produced by lightning from GOME and NLDN data: A case study in the Gulf of Mexico — •Steffen Beirle1, N. Spichtinger2, A. Stohl3, K. Cummins4, T. Turner4, D. Boccippio5, O. Cooper6, M. Wenig7, M. Grzegorski1, U. Platt1, and T. Wagner 1 — 1IUP Heidelberg, Germany — 2TUM Munich, Germany — 3NILU, Norway — 4Vaisala, USA — 5GHCC, USA — 6NOAA, USA — 7NASA GSFC, USA
Nitrogen oxides (NOx=NO+NO2) play an important role in tropospheric chemistry, in particular in catalytic ozone production. Lightning provides a natural source of nitrogen oxides. The range of recent estimates of lightning produced NOx (LNOx) still are of the order of 5 Tg [N] per year with still high uncertainties in the range of one order of magnitude. The Global Ozone Monitoring Experiment (GOME) on board the ESA-satellite ERS-2 allows the retrieval of tropospheric vertical column densities (TVCDs) of NO2 on a global scale. Here we present the GOME NO2 measurement directly over a large convective system over the Gulf of Mexico. Simultaneously, cloud-to-ground flashes are counted by the U.S. National Lightning Detection Network (NLDN). A series of 14 GOME pixels shows largely enhanced TVCDs over thick and high clouds, coinciding with strong lightning activity. The enhancements can not be explained by transport of anthropogenic NOx and must be due to fresh production of LNOx. A quantitative analysis, accounting in particular for the visibility of LNOx from satellite, yields a LNOx production of 77 (27-230) moles of NOx, or 1.1 (0.4-3.2) kg [N], per flash. This corresponds to a global LNOx production of 1.5 (0.5-4.5) Tg [N]/yr.