Photochemical modeling of the earth's stratosphere

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1984

OSTI ID:6218773

Froidevaux, L

A one-dimensional photochemical model of the Earth's stratosphere has been developed in order to provide an up-to-date comparison with mid-latitude observations. The first-order effects of the inclusion of the diffuse radiation in a spherical shell atmosphere, for solar zenith angles close to 90/sup 0/ are demonstrated. Changes in model concentrations are largest for short-lived radicals such as O, OH, ClO, and NO in the lower stratosphere, but relatively small compared to current observational uncertainties. It is proposed that a significant overestimate of the molecular oxygen absorption cross section near 210 nm is in large part responsible for the discrepancy between observed and modeled vertical profiles of some halocarbons (CFCl/sub 3/ in particular). The diurnal variation of ClO observed from the ground by P. Solomon and coworkers is consistent with these diurnal model results and provides indirect evidence for the existence of ClONO/sub 2/. The main uncertainty relating to fluorine products concerns the value of the quantum yield for COF/sub 2/ photodissociation. The mean observed mid-latitude ozone abundance from about 35 to 50 km is up to 60% greater than current model results. Given the uncertainties in laboratory photochemical data, it is difficult to reconcile theory and observations; the model chemistry might be missing a significant ingredient. Certain observations of a daytime increase in ozone near 40 km are also puzzling. Fast isotopic exchange reactions between O and O/sub 2/ dominate the heavy ozone photochemistry, so that a large enhancement in heavy ozone cannot be sustained in the stratosphere, contrary to the observations of K. Mauersberger.

• OSTI ID: 6218773
• Country of Publication: United States
• Language: English

Related Subjects

500200* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
AIR POLLUTION
ATMOSPHERIC CHEMISTRY
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISTRY
CHLORINE COMPOUNDS
CHLORINE OXIDES
DAILY VARIATIONS
EARTH ATMOSPHERE
ECOLOGICAL CONCENTRATION
ELEMENTS
FLUORINE
HALOGEN COMPOUNDS
HALOGENS
HYDROGEN COMPOUNDS
HYDROXIDES
MATHEMATICAL MODELS
NITRIC OXIDE
NITROGEN COMPOUNDS
NITROGEN OXIDES
NONMETALS
OXIDES
OXYGEN COMPOUNDS
OZONE
PHOTOCHEMICAL OXIDANTS
PHOTOCHEMICAL REACTIONS
PHOTOCHEMISTRY
POLLUTION
STRATOSPHERE
VARIATIONS