Atmospheric Chemistry and Physics www.atmos-chem-phys.net 1680-7316 1680-7324 9 21 2009 10.5194/acp-9-8377-2009 http://www.atmos-chem-phys.net/9/8377/2009/ http://www.atmos-chem-phys.net/9/8377/2009/acp-9-8377-2009.html http://www.atmos-chem-phys.net/9/8377/2009/acp-9-8377-2009.pdf 8377 8412 2009-11-05 NOx production by lightning in Hector: first airborne measurements during SCOUT-O3/ACTIVE H. Huntrieser heidi.huntrieser@dlr.de H. Schlager M. Lichtenstern A. Roiger P. Stock A. Minikin H. Höller K. Schmidt H.-D. Betz G. Allen S. Viciani A. Ulanovsky F. Ravegnani D. Brunner Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Oberpfaffenhofen, Germany nowcast GmbH, München, Germany Physics Department, University of Munich, Germany School of Earth, Atmospheric & Environmental Sciences, University of Manchester, UK Istituto Nazionale di Ottica Applicata (CNR-INOA), Firenze, Italy Central Aerological Observatory, Moscow, Russia Institute of Atmospheric Sciences and Climate (CNR-ISAC), Bologna, Italy Laboratory for Air Pollution and Environmental Technology, Empa, Swiss Federal Laboratories for Materials Testing and Research, Dübendorf, Switzerland During the SCOUT-O3/ACTIVE field phase in November–December 2005, airborne in situ measurements were performed inside and in the vicinity of thunderstorms over northern Australia with several research aircraft (German Falcon, Russian M55 Geophysica, and British Dornier-228. Here a case study from 19 November is presented in detail on the basis of airborne trace gas measurements (NO, NOy, CO, O3) and stroke measurements from the German LIghtning Location NETwork (LINET), set up in the vicinity of Darwin during the field campaign. The anvil outflow from three different types of thunderstorms was probed by the Falcon aircraft: (1) a continental thunderstorm developing in a tropical airmass near Darwin, (2) a mesoscale convective system (MCS), known as Hector, developing within the tropical maritime continent (Tiwi Islands), and (3) a continental thunderstorm developing in a subtropical airmass ~200 km south of Darwin. For the first time detailed measurements of NO were performed in the Hector outflow. The highest NO mixing ratios were observed in Hector with peaks up to 7 nmol mol−1 in the main anvil outflow at ~11.5–12.5 km altitude. The mean NOx (=NO+NO2) mixing ratios during these penetrations (~100 km width) varied between 2.2 and 2.5 nmol mol−1. The NOx contribution from the boundary layer (BL), transported upward with the convection, to total anvil-NOx was found to be minor (<10%). On the basis of Falcon measurements, the mass flux of lightning-produced NOx (LNOx) in the well-developed Hector system was estimated to 0.6–0.7 kg(N) s−1. The highest average stroke rate of the probed thunderstorms was observed in the Hector system with 0.2 strokes s−1 (here only strokes with peak currents ≥10 kA contributing to LNOx were considered). The LNOx mass flux and the stroke rate were combined to estimate the LNOx production rate in the different thunderstorm types. For a better comparison with other studies, LINET strokes were scaled with Lightning Imaging Sensor (LIS) flashes. The LNOx production rate per LIS flash was estimated to 4.1–4.8 kg(N) for the well-developed Hector system, and to 5.4 and 1.7 kg(N) for the continental thunderstorms developing in subtropical and tropical airmasses, respectively. 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