You can manage bookmarks using lists, please log in to your user account for this.
Media type:
E-Article
Title:
Mesospheric HOx chemistry from diurnal microwave observations of HO2, O3, and H2O
Contributor:
Sandor, Brad J.;
Clancy, R. Todd
imprint:
American Geophysical Union (AGU), 1998
Published in:Journal of Geophysical Research: Atmospheres
Language:
English
DOI:
10.1029/98jd00432
ISSN:
0148-0227
Origination:
Footnote:
Description:
<jats:p>Microwave (λ ∼1.2 mm) spectral emission line observations of HO<jats:sub>2</jats:sub>, O<jats:sub>3</jats:sub>, and H<jats:sub>2</jats:sub><jats:sup>18</jats:sup>O from the upper stratosphere and mesosphere (45–80 km) were obtained in April 1992, January 1993, and April and December 1996, using the Kitt Peak National Radio Astronomy Observatory (NRAO). Significant improvements to this, the only method for making mesospheric HO<jats:sub>2</jats:sub> measurements, have been made with hardware upgrades allowing observation of a stronger emission line than described in previous work. Data analysis has been improved by (1) recalibration of the (primarily astronomical) instrument for atmospheric studies, (2) incorporation of updated laboratory spectroscopic work, and (3) use of an improved photochemical model. Diurnal HO<jats:sub>2</jats:sub> data analyses employing 30 min to 2 hour observations show measured HO<jats:sub>2</jats:sub> abundances at 50–80 km altitude are 23–47% higher than photochemical model values at mid day, agree with model values prior to 0900 local time (LT), and exceed model mixing ratios by 70–100% immediately after sunset. Coordinated diurnal measurements of mesospheric O<jats:sub>3</jats:sub> find a model O<jats:sub>3</jats:sub> deficit consistent with model underprediction of ozone seen in all comparable data sets. HO<jats:sub>2</jats:sub> observations are critical to understanding mesospheric chemistry, in that simultaneous model underpredictions of this ozone‐destroying species and of ozone place stringent constraints on proposed sources of model error. The ozone model deficit and 0900–1800 HO<jats:sub>2</jats:sub> model deficit are simultaneously resolved with a 40% reduction in the rate coefficient k(HO<jats:sub>2</jats:sub> + O → OH + O<jats:sub>2</jats:sub>). We review other modeling studies of this rate change, indicating it has negligible effect in the lower stratosphere and improves a diverse set of model results from the upper stratosphere to mesopause.</jats:p>