Vertical profiles of lightning-produced NO sub(2) enhancements in the upper troposphere observed by OSIRIS

• Published in: Atmospheric chemistry and physics discussions 2007-04, Vol.7 (2), p.5013-5051
• Main Authors: Sioris, CE, McLinden, CA, Martin, R V, Sauvage, B, Haley, C S, Lloyd, N D, Llewellyn, E J, Bernath, P F, Boone, C D, Brohede, S, McElroy, C T
• Format: Article
• Language: English
• ISSN: 1680-7367; 1680-7375

The purpose of this study is to perform a global search of the upper troposphere (z greater than or equal to 10 km) for enhancements of nitrogen dioxide and determine their sources. We have searched two years (May 2003-May 2005) of OSIRIS (Optical Spectrograph and Infrared Imager System) operational NO sub(2) data (version 2.3/2.4) to find large enhancements in the observations by comparing concentrations with those predicted by a photochemical model and by identifying local maxima in NO sub(2) volume mixing ratio. We find that lightning is the main production mechanism responsible for the large enhancements in OSIRIS NO sub(2) observations as expected. Similar patterns in the abundances and spatial distribution of the NO sub(2) enhancements are obtained by perturbing the lightning within the GEOS-Chem 3-dimensional chemical transport model. In most cases, the presence of lightning is confirmed with coincident imagery from LIS (Lightning Imaging Sensor) and the spatial extent of the NO sub(2) enhancement is mapped using nadir observations of tropospheric NO sub(2) at high spatial resolution from SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Chartography) and OMI (Ozone Monitoring Instrument). The combination of the lightning and chemical sensors allows us to investigate globally the role of lightning to the abundance of NO sub(2) in the upper troposphere (UT). This is the first application of satellite-based limb scattering to study upper tropospheric NO sub(2). The spatial and temporal distribution of NO sub(2) enhancements from lightning (May 2003-May 2005) is investigated. The NO sub(2) from lightning generally occurs at 12 to 13 km more frequently than at 10 to 11 km. This is consistent with the notion that most of the NO sub(2) is forming and persisting near the cloud top altitude in the tropical upper troposphere. The latitudinal distribution is mostly as expected. In general, the thunderstorms exhibiting weaker vertical development (e.g. 11 less than or equal to z less than or equal to 13 km) extend latitudinally as far poleward as 45 degree but the thunderstorms with stronger vertical development (z greater than or equal to 14 km) tend to be located within 33 degree of the equator. There is also the expected hemispheric asymmetry in the frequency of the NO sub(2) enhancements, as most were observed in the Northern Hemisphere for the period analyzed.