Towards a robust estimate of the global lightning nitrogen oxides source rate and its error bound

Year: 2006

Authors: Schumann U., Kurz C., Schlager H., Huntrieser H., Emmons L., Labrador L., Meijer E., Ulanovsky A., Viciani S.

Autors Affiliation: Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Physik der Atmosphäre, Oberpfaffenhofen, 82234 Wessling, Germany;
National Center for Atmospheric Research (NCAR), Boulder, Colorado, USA;
Max-Planck Institut (MPI) für Chemie, Mainz, Germany;
Royal Netherlands Meteorological Institute (KNMI), De Bilt, The Netherlands;
Central Aerological Observatory (CAO), Dogoprudny, Russia;
CNR – Instituto Nazionale di Ottica Applicata, Largo E. Fermi 6,
50125 Firenze, Italy

Abstract: A weighted least square fit method is introduced which provides best estimates for the annually mean global source strength S of lightning induced nitrogen oxides (LNOx) together with random and systematic error bounds. The method is demonstrated using data measured in-situ with airborne instruments near deep convection over a tropical continent at altitudes up to 20 km in Southern Brazil in February/March 2004 and February 2005 during the EU-project \”Tropical Convection, Cirrus, and Nitrogen Oxides Experiment\” (TROCCINOX). Model results for air composition along the flight paths for at least two values of S were provided by several global chemical transport models. LNOx estimates are obtained not only from NO mixing ratio data measured close to thunderstorms with fresh LNOx sources, but also from O3 and CO data because of their LNOx sensitivity due to tropospheric photochemistry during the chemical life-time of theses species. The best estimate of the annual and global mean LNOx source value computed for the given data is S = 4.8 ± 2.5 Tg a-1 (in mass units of nitrogen per year). Ongoing model improvements and inclusion of data from further in-situ and remote sensing measurements (including SCIAMACHY NO2 columns) and data from other periods and latitudes may still change this result.

Conference title: ESA – ESRIN (European Space Research INstitute): Atmospheric Science Conference
Place: Frascati (Roma), Italy

KeyWords: Airborne telescopes; Error analysis; Least squares approximations; Lightning; Photochemical reactions; Robustness (control systems); Troposphere, Global lightning; Least square fit method; Lightning induced nitrogen oxides (LNO); Systematic error bounds, Nitrogen oxides