Apel, E. C. and Olson, J. R. and Crawford, J. H. and Hornbrook, R. S. and Hills, A. J. and Cantrell, C. A. and Emmons, L. K. and Knapp, D. J. and Hall, S. and Mauldin, R. L., III and Weinheimer, A. J. and Fried, A. and Blake, D. R. and Crounse, J. D. and St. Clair, J. M. and Wennberg, P. O. and Diskin, G. S. and Fuelberg, H. E. and Wisthaler, A. and Milkoviny, T. and Brune, W. and Riemer, D. D. (2012) Impact of the deep convection of isoprene and other reactive trace species on radicals and ozone in the upper troposphere. Atmospheric Chemistry and Physics, 12 (2). pp. 1135-1150. ISSN 1680-7316 http://resolver.caltech.edu/CaltechAUTHORS:20120323-112554276
- Published Version
Creative Commons Attribution.
Use this Persistent URL to link to this item: http://resolver.caltech.edu/CaltechAUTHORS:20120323-112554276
Observations of a comprehensive suite of inorganic and organic trace gases, including non-methane hydrocarbons (NMHCs), halogenated organics and oxygenated volatile organic compounds (OVOCs), obtained from the NASA DC-8 over Canada during the ARCTAS aircraft campaign in July 2008 illustrate that convection is important for redistributing both long- and short-lived species throughout the troposphere. Convective outflow events were identified by the elevated mixing ratios of organic species in the upper troposphere relative to background conditions. Several dramatic events were observed in which isoprene and its oxidation products were detected at hundreds of pptv at altitudes higher than 8 km. Two events are studied in detail using detailed experimental data and the NASA Langley Research Center (LaRC) box model. One event had no lightning NO_x (NO + NO_2) associated with it and the other had substantial lightning NO_x (LNO_x > 1 ppbv). When convective storms transport isoprene from the boundary layer to the upper troposphere and no LNO_x is present, OH is reduced due to scavenging by isoprene, which serves to slow the chemistry, resulting in longer lifetimes for species that react with OH. Ozone and PAN production is minimal in this case. In the case where isoprene is convected and LNO_x is present, there is a large effect on the expected ensuing chemistry: isoprene exerts a dominant impact on HO_x and nitrogen-containing species; the relative contribution from other species to HO_x, such as peroxides, is insignificant. The isoprene reacts quickly, resulting in primary and secondary products, including formaldehyde and methyl glyoxal. The model predicts enhanced production of alkyl nitrates (ANs) and peroxyacyl nitrate compounds (PANs). PANs persist because of the cold temperatures of the upper troposphere resulting in a large change in the NO_x mixing ratios which, in turn, has a large impact on the HO_x chemistry. Ozone production is substantial during the first few hours following the convection to the UT, resulting in a net gain of approximately 10 ppbv compared to the modeled scenario in which LNO_x is present but no isoprene is present aloft.
|Additional Information:||© 2012 Author(s). This work is distributed under the Creative Commons Attribution 3.0 License. Received: 23 August 2011. Published in Atmos. Chem. Phys. Discuss.: 5 October 2011. Revised: 10 January 2012. Accepted: 12 January 2012. Published: 27 January 2012. The authors thank the crew and support team for the NASA DC-8 aircraft, and Mary Barth, Frank Flocke and John Orlando for helpful comments and discussion. The authors gratefully acknowledge the financial support of NASA (Grant No. X08AD33G). PTR-MS measurements were supported by the Austrian Research Promotion Agency (FFG-ALR) and the Tiroler Zukunftstiftung, and were carried out with the help/support of M. Graus, A. Hansel and T. D. Maerk. The National Center for Atmospheric Research is sponsored by the National Science Foundation. Any opinions, findings and conclusions or recommendations expressed in the publication are those of the authors and do not necessarily reflect the views of the National Science Foundation. Edited by: J. W. Bottenheim|
|Official Citation:||Apel, E. C., Olson, J. R., Crawford, J. H., Hornbrook, R. S., Hills, A. J., Cantrell, C. A., Emmons, L. K., Knapp, D. J., Hall, S., Mauldin III, R. L., Weinheimer, A. J., Fried, A., Blake, D. R., Crounse, J. D., Clair, J. M. St., Wennberg, P. O., Diskin, G. S., Fuelberg, H. E., Wisthaler, A., Mikoviny, T., Brune, W., and Riemer, D. D.: Impact of the deep convection of isoprene and other reactive trace species on radicals and ozone in the upper troposphere, Atmos. Chem. Phys., 12, 1135-1150, doi:10.5194/acp-12-1135-2012, 2012.|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||23 Mar 2012 21:29|
|Last Modified:||26 Dec 2012 14:58|
Repository Staff Only: item control page