In situ measurements of the NO{sub 2}/NO ratio for testing atmospheric photochemical models

Journal Article · Tue Nov 15 04:00:00 EST 1994 · Geophysical Research Letters

DOI:https://doi.org/10.1029/94GL02717· OSTI ID:57034

Jaegle, L; Webster, C R; May, R D ^[1]; Fahey, D W; Woodbridge, E L; Keim, E R; Gao, R S; Proffitt, M H ^[2]; Stimpfle, R M; Salawitch, R J ^[3]

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1. California Institute of Technology, Pasadena, CA (United States)
2. NOAA Aeronomy Lab., Boulder, CO (United States)
3. Harvard Univ., Cambridge, MA (United States); and others

Simultaneous in situ measurements of NO{sub 2}, NO, O{sub 3}, ClO, pressure and temperature have been made for the first time, presenting a unique opportunity to test the 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 NO{sub 2}/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 NO{sub 2} photolysis rates. At each measurement point the daytime NO{sub 2}/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 + O{sub 3} reaction rate and of the NO{sub 2} cross-sections in the 200-220 K temperature range characteristic of the lower stratosphere would allow for a more robust test of the knowledge of NO{sub 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. 22 refs., 4 figs., 1 tab.

• OSTI ID: 57034
• Journal Information: Geophysical Research Letters, Journal Name: Geophysical Research Letters Journal Issue: 23 Vol. 21; ISSN GPRLAJ; ISSN 0094-8276
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ATMOSPHERIC CHEMISTRY
CHLORINE OXIDES
ECOLOGICAL CONCENTRATION
NITRIC OXIDE
NITROGEN DIOXIDE
OZONE
PHOTOCHEMISTRY
STRATOSPHERE