Two-dimensional tomographic retrieval of MIPAS/ENVISAT measurements of ozone and related species

Observations from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) were analysed with the two-dimensional GMTR retrieval system in order to obtain fields of ozone and several molecular species related to ozone chemistry: HNO3, N2O, NO2, N2O5, ClONO2, COF2, CFC-11 and CFC-12. MIPAS measures mid-infrared emission of the atmosphere both during the day and at night time with global coverage. Observing the atmosphere with limb viewing geometries, the instrument is able to resolve finer vertical structures than with nadir instruments, thus enabling the investigation of ozone height-dependent processes. With the currently planned mission extended up to 2014, MIPAS can provide both short-term resolution and long-term trends needed for studying ozone. The adopted GMTR algorithm permits us to resolve the horizontal inhomogeneities of the atmosphere that are modelled using a two-dimensional discretization of the atmosphere. It is therefore especially suitable for analysing portions of the atmosphere where strong gradients such as at the ozone hole may be poorly reproduced by common horizontal homogeneous one-dimensional retrievals. The adopted strategy is well suited for a refined analysis and a correct monitoring of the ozone recovery, as required by the Montreal Protocol and successive amendments.