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In Situ Measurements of the NO2/NO Ratio for Testing Atmospheric Photochemical ModelsSimultaneous in situ measurements of NO2, NO, O3, ClO, pressure and temperature have been made for the first time, presenting a unique opportunity to test our current understanding of the photochemistry of the lower stratosphere. Data were collected from several flights of the ER-2 aircraft at mid-latitudes in May 1993 during NASA's Stratospheric Photochemistry, Aerosols and Dynamics Expedition (SPADE). The daytime ratio of NO2/NO remains fairly constant at 19 km with a typical value of 0.68 and standard deviation of +/- 0.17. The ratio observations are compared with simple steady-state calculations based on laboratory-measured reaction rates and modeled NO2 photolysis rates. At each measurement point the daytime NO2/NO with its measurement uncertainty overlap the results of steady-state calculations and associated uncertainty. However, over all the ER-2 flights examined, the model systematically overestimates the ratio by 40% on average. Possible sources of error are examined in both model and measurements. It is shown that more accurate laboratory determinations of the NO + O3 reaction rate and of the NO2 cross-sections in the 200-220 K temperature range characteristic of the lower stratosphere would allow for a more robust test of our knowledge of NO(x) photochemistry by reducing significant sources of uncertainties in the interpretation of stratospheric measurements. The present measurements are compared with earlier observations of the ratio at higher altitudes.
Document ID
20000062470
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
Authors
Jaegle, L.
(California Inst. of Tech. Pasadena, CA United States)
Webster, C. R.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA United States)
May, R. D.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA United States)
Fahey, D. W.
(National Oceanic and Atmospheric Administration United States)
Woodbridge, E. L.
(National Oceanic and Atmospheric Administration United States)
Keim, E. R.
(National Oceanic and Atmospheric Administration United States)
Gao, R. S.
(National Oceanic and Atmospheric Administration United States)
Proffitt, M. H.
(National Oceanic and Atmospheric Administration United States)
Stimpfle, R. M.
(Harvard Univ. Cambridge, MA United States)
Salawitch, R. J.
(Harvard Univ. Cambridge, MA United States)
Date Acquired
August 19, 2013
Publication Date
November 15, 1994
Publication Information
Publication: Geophysical Research Letters
Publisher: American Geophysical Union
Volume: 21
Issue: 23
ISSN: 0094-8534
Subject Category
Environment Pollution
Report/Patent Number
Paper 94GL02717
Distribution Limits
Public
Copyright
Other

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