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Establishing the Dependence of [HO2]/[OH] on Temperature, Halogen Loading, O3, and NO(x) Based on in Situ Measurements from the NASA ER-2In situ observations of OH and HO2 from the Airborne Southern Hemisphere Ozone Experiment/Measurements for Assessing the Effects of Stratospheric Aircraft (ASHOE/MAESA), Stratospheric TRacers of Atmospheric Transport (STRAT), and Polar Ozone Loss in the Arctic Region in Summer (POLARIS) NASA ER-2 field campaigns are used to examine the partitioning of HO(x) in the lower stratosphere (tropopause to approx.21 km) and upper troposphere (approx.10 km to tropopause). These measurements span a latitude range from 70degS to 90degN and a variety of atmospheric conditions as a result of seasonal changes and altitude. The response of the observed [HO2]/[OH] to changes in temperature, [03], [CO], [NO], [CIO], and [BrO] is investigated. The measured ratio is accurately described (approx.+/-10%) by a steady-state model constrained by the measured mixing ratios of O3, CO, NO, CIO, and BrO, where the model is valid for conditions of HO(x) cycling much faster than HO(x) production and loss. The concentration of HO2 depends on [OH], which, to first order, has been observed to be a simple function of the solar zenith angle in the lower stratosphere. The partitioning between OH and HO2 is controlled by the local chemistry between the HO, radicals and O3, CO, NO, CIO, and BrO. The response of [HO(x)] to changes in [NO(x)] and [O3] is demonstrated. Further observations are necessary to illustrate the response of HO(x) to changes in halogen concentrations. A quantitative understanding of [HO2]/[OH] is important, since many of the reactions that control this ratio are directly involved in catalytic removal of O3 in the lower stratosphere and production of O3 in the upper troposphere.
Document ID
20010064079
Acquisition Source
Jet Propulsion Laboratory
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Lanzendorf, E. J.
(Harvard Univ. Cambridge, MA United States)
Hanisco, T. F.
(Harvard Univ. Cambridge, MA United States)
Wennberg, P. O.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA United States)
Cohen, R. C.
(California Univ. Berkeley, CA United States)
Stimpfle, R. M.
(Harvard Univ. Cambridge, MA United States)
Anderson, J. G.
(Harvard Univ. Cambridge, MA United States)
Gao, R. S.
(National Oceanic and Atmospheric Administration Boulder, CO United States)
Margitan, J. J.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA United States)
Bui, T. P.
(NASA Ames Research Center Moffett Field, CA United States)
Date Acquired
August 20, 2013
Publication Date
January 1, 2001
Publication Information
Publication: Journal of Physical Chemistry A
Publisher: American Chemical Society
Volume: 105
Issue: 9
Subject Category
Environment Pollution
Distribution Limits
Public
Copyright
Other

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