On the origin of tropospheric ozone and NOx over the tropical South Pacific

Authors

Martin G. Schultz, Harvard University
Daniel J. Jacob, Harvard University
Yuhang Wang, Harvard University
Jennifer A. Logan, Harvard University
Elliot L. Atlas, National Center for Atmospheric Research
Donald R. Blake, University of California, Irvine
Nicola J. Blake, University of California, Irvine
John D. Bradshaw
Edward V. Browell, NASA Langley Research Center
Marta A. Fenn, NASA Langley Research Center
Frank Flocke, National Center for Atmospheric Research
Gerald L. Gregory, NASA Langley Research Center
Brian G. Heikes, University of Rhode Island
Glen W. Sachse, University of Rhode Island
Scott T. Sandholm, Georgia Institute of Technology
Richard E. Shetter, National Center for Atmospheric Research
Hanwant B. Singh, NASA Ames Research Center
R. W. Talbot, University of New Hampshire Durham

Document Type

Article

Date of Original Version

3-20-1999

Abstract

The budgets of ozone and nitrogen oxides (NOx = NO + NO2) in the tropical South Pacific troposphere are analyzed by photochemical point modeling of aircraft observations at 0-12 km altitude from the Pacific Exploratory Mission-Tropics A campaign flown in September-October 1996. The model reproduces the observed NO2/NO concentration ratio to within 30% and has similar success in simulating observed concentrations of peroxides (H2O2, CH3OOH), lending confidence in its use to investigate ozone chemistry. It is found that chemical production of ozone balances only half of chemical loss in the tropospheric column over the tropical South Pacific. The net loss is 1.8 x 1011 molecules cm-2 s-1. The missing source of ozone is matched by westerly transport of continental pollution into the region. Independent analysis of the regional ozone budget with a global three-dimensional model corroborates the results from the point model and reveals the importance of biomass burning emissions in South America and Africa for the ozone budget over the tropical South Pacific. In this model, biomass burning increases average ozone concentrations by 7-8 ppbv throughout the troposphere. The NOx responsible for ozone production within the South Pacific troposphere below 4 km can be largely explained by decomposition of peroxyacetylnitrate (PAN) transported into the region with biomass burning pollution at higher altitudes. Copyright 1999 by the American Geophysical Union.

Publication Title, e.g., Journal

Journal of Geophysical Research Atmospheres

Volume

104

Issue

D5

Citation/Publisher Attribution

Schultz, Martin G., Daniel J. Jacob, Yuhang Wang, Jennifer A. Logan, Elliot L. Atlas, Donald R. Blake, Nicola J. Blake, John D. Bradshaw, Edward V. Browell, Marta A. Fenn, Frank Flocke, Gerald L. Gregory, Brian G. Heikes, Glen W. Sachse, Scott T. Sandholm, Richard E. Shetter, Hanwant B. Singh, and R. W. Talbot. "On the origin of tropospheric ozone and NOx over the tropical South Pacific." Journal of Geophysical Research Atmospheres 104, D5 (1999). doi: 10.1029/98JD02309.