Daily ozone vertical profile model built on geophysical grounds, for column retrieval from atmospheric high-resolution infrared spectra

The retrieval of column abundances of atmospheric gases from atmospheric in frared spectra necessarily depends on the choice of the a priori vertical p rofiles of the atmospheric species involved. Most commonly a standard profi le is adopted, and some additional parameter is introduced in the retrieval algorithm for improving the final result. This parameter may be unrelated to geophysical arguments. For the retrieval of ozone columns, it is propose d here to use a model of a priori O-3 vertical profiles which better reflec t the real state of the atmosphere at the time and location of the measurem ent. The model profiles depend on the daily local thermal tropopause height and include a climatological seasonality. The model has been developed for the retrieval of ozone columns from high-resolution Fourier transform infr ared (FTIR) solar absorption measurements at the International Scientific S tation of the Jungfraujoch in the Swiss Alps. It is demonstrated that the u se of the model significantly improves the quality of the spectral fits whi le minimizing the need for adjusting additional nongeophysical parameters t o compensate for atmospheric changes and that it enhances the accuracy of t he retrieved O-3 column data. Such is done by comparison of the retrieved F TIR O-3 data with validated independent O-3 data sets from co-located Syste me d'Analyse par Observations Zenithales and nearby Brewer instruments. Con trary to some other approaches for improving the FTIR O-3 retrieval, the mo del concept developed here can be applied to O-3 observations at any midlat itude site, and it can be implemented in an operational retrieval procedure .