ANALYTIC MODELS FOR THE OZONE RADIATIVE ABSORPTION RATE AT 9.6-MU-M IN THE MESOSPHERE

Analytic models of the ozone radiative absorption rate in the 9.6-mu-m band were developed on the basis of negligible line overlap in the mesosphere and low thermosphere. In the first model the line intensity distribution was represented by an S-1-beta tailed exponential distribution. The band escape function was calculated by an integration over a single line profile with the diffusivity effect included exactly. Because ozone absorption is weak in the mesosphere, the major contribution to the absorption rate comes mainly from the strongest lines and the distribution function reduces to exponential form. In our second model, approximations for the diffusivity effect (diffusivity factor), line profile (Voigt), and line intensity distribution (Malkmus) were introduced to obtain an analytic expression for the band escape function. Both models yield accurate results for three examples that span the range of temperatures and ozone profiles encountered in the mesosphere and lower thermosphere with the maximum fractional errors never exceeding 4%. These two models are particularly suited for non-LTE calculations and analysis of remote sensing data of the ozone 9.6-mu-m band in the mesosphere and lower thermosphere.