HR: 1330h
AN: SA43A-08    [Abstracts]
TI: Processes That Account for the Ozone Maximum at the Mesopause
AU: * Smith, A K
EM: aksmith@ucar.edu
AF: ACD/NCAR, P O Box 3000, Boulder, CO 80307 United States
AU: Marsh, D R
EM: marsh@ucar.edu
AF: ACD/NCAR, P O Box 3000, Boulder, CO 80307 United States
AB: The presence of a maximum in ozone density and mixing ratio in the mesopause region has been known for several decades although the measurement data base is still limited. We have simulated the ozone maximum in a 3-dimensional dynamical chemical model. The largest component of the diurnal cycle in ozone is the difference between low concentrations in sunlight and high concentrations in darkness. However, the diurnal variability also has strong contributions from atmospheric tides and from slow changes in the background chemical concentrations following sunrise and sunset. In this study, we find that the magnitude of the ozone secondary maximum is closely tied to the temperature. The very cold temperatures at the mesopause accelerate the formation of ozone and inhibit the loss. This factor and the location of the atomic oxygen density maximum both contribute in approximately equal measure to determining the altitude of the ozone layer and both have a major impact on the ozone variability. The magnitude of the nighttime ozone maximum is sensitive to the eddy and molecular diffusion rates through the influence of these processes on the concentration of hydrogen, which destroys ozone.
DE: 0340 Middle atmosphere--composition and chemistry
DE: 0341 Middle atmosphere--constituent transport and chemistry (3334)
SC: SPA-Aeronomy [SA]
MN: 2005 Joint Assembly