Stratospheric hydroxyl radical concentrations: new limitations suggested by observations of gaseous and particulate sulfur

Journal Article · Fri Feb 20 00:00:00 EST 1981 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JC086iC02p01129· OSTI ID:6773212

Turco, R P; Whitten, R C; Toon, O B; Inn, E C.Y.; Hamill, P

A one-dimensional aerosol model is used to investigate the sensitivity of the stratospheric distributions of gaseous sulfur compounds and sulfate aerosol particles to changes in OH and CS/sub 2/ concentrations, in eddy diffusion coefficients, and in key chemical rate constants. By comparing model predictions with recent observational data for So/sub 2/, OCS, and particulates, the following conclusions are reached. With regard to atmospheric sulfur, it appears that CS/sub 2/ is only a secondary source of sulfur for the stratosphere relative to OCS and that background tropospheric CS/sub 2/ concentrations are likely to be <70 pptv. It is also found that under stratospheric conditions, the rate coefficients for the reactions of OH with OCS and CS/sub 2/ may be substantially smaller than the room temperature laboratory values of Kurylo (1978). The most important conclusion of the present study, however, is that OH concentrations below 30 km may be over-estimated by a factor of 3 or more in current photochemical models. Plausibility arguments for lower atmospheric OH concentrations are supported by recent laboratory studies of the pressure, the temperature, and the humidity dependences of OH an HO/sub 2/ chemical kinetic systems. New reaction rate data bearing on this problem are reviewed. A reduced level of stratospheric OH has strong implications for ozone perturbations attributable to aircraft NO/sub x/ emissions, to nitrogen fertilizer usage, and to halocarbon releases. Such ozone perturbations are simulated using a one-dimensional atmospheric photochemistry model in which the OH concentrations are reduced in accordance with the sulfur sensitivity tests highlighted above. Owing to the reduction in OH, SST NO/sub x/ injections at 20 km act to decrease ozone, not increase it as had been thought previously. Nitrous oxide produced by fertilizer decomposition is also found to be more destructive of ozone. On the other hand, fluorocarbon-induced ozone depletions are somewhat smaller.

• Research Organization: RandD Associates, Marina del Rey, California 90291
• OSTI ID: 6773212
• Journal Information: J. Geophys. Res.; (United States), Vol. 86:C2
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
HYDROXYL RADICALS
STRATOSPHERE
ATMOSPHERIC CHEMISTRY
CARBON OXYSULFIDE
CARBON SULFIDES
ONE-DIMENSIONAL CALCULATIONS
OZONE LAYER
SULFUR DIOXIDE
CARBON COMPOUNDS
CHALCOGENIDES
CHEMISTRY
EARTH ATMOSPHERE
LAYERS
OXIDES
OXYGEN COMPOUNDS
RADICALS
SULFIDES
SULFUR COMPOUNDS
SULFUR OXIDES
500200* - Environment
Atmospheric- Chemicals Monitoring &amp; Transport- (-1989)