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A description and summary of the latest edition of the AFGL HITRAN molecular absorption parameters database are presented. This new database combines the information for the seven principal atmospheric absorbers and twenty-one additional molecular species previously contained on the AFGL atmospheric absorption line parameter compilation and on the trace gas compilation. In addition to updating the parameters on earlier editions of the compilation, new parameters have been added to this edition such as the self-broadened halfwidth, the temperature dependence of the air-broadened halfwidth, and the transition probability. The database contains 348043 entries between 0 and 17,900 cm(-1). A FORTRAN program is now furnished to allow rapid access to the molecular transitions and for the creation of customized output. A separate file of molecular cross sections of eleven heavy molecular species, applicable for qualitative simulation of transmission and emission in the atmosphere, has also been provided.

A Hamiltonian for vibration and rotation in polyatomic molecules is described which is general for large and small amplitude motion and most choices of rotating axes. An analysis of the effect of a change in the definition of the rotating axes is presented and the convergence properties of perturbation expansions of the Hamiltonian are discussed. Some rotation—vibration terms converge slowly in an arbitrary set of axes, and the effect of these terms is shown to be equivalent to rotation from the original set of axes to a new set of axes in which the coriolis terms are minimized. Ways to find this new set of axes are discussed, and application of the results of this work to the microwave spectra of several molecules is presented.

The velocity averaging of co11ision cross sections produces non-Lorentz line shapes, even at densities where Doppler broadening is not apparent. The magnitude of the effects will be described using a model in which the collision broadening depends on a simple velocity power law. The effect of the modified profile on experimental measures of linewidth, shift and amplitude will be examined and an improved approximate line shape will be derived.

[1] Using measurements from the MLS/Aura and GOMOS/Envisat instruments together with a 1-D ion and neutral chemistry model we study the changes in odd hydrogen and ozone in the mesosphere during the January 2005 solar proton event. The unique observational data allow us for the first time to directly test the HO x production theory which involves complex ion chemistry. MLS measurements from the northern polar region show increases of OH concentrations by over 100% around the stratopause, and by up to one order of magnitude in the middle mesosphere after the onset of the SPE. GOMOS measurements indicate decreases in O 3 concentration throughout the lower and middle mesosphere, by up to 90%. The model predictions are in reasonable agreement with the observations. We point out that models using the so-called P HOx /Q parameterization to include the effects of ion chemistry could underestimate the HO x production and the resulting ozone depletion. Citation: Verronen, P. T.,

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