Demonstration and validation of the φ-IASI inversion scheme with NAST-I data

The physical forward/inverse scheme φ-IASI has been applied to the retrieval of atmospheric vertical profiles of temperature, water vapour and ozone by inverting high spectral infrared observations recorded by the NAST-I Fourier Transform Spectrometer. For the retrieval exercise we have used clear-sky spectra recorded over the sea surface on the night of 9–10 September 2004, during the Italian phase of the EAQUATE field campaign. During the campaign NAST-I flew on board the NASA Proteus aircraft at an altitude of 15 km. Retrievals have been compared to radiosonde observations, profiles from the ECMWF analysis and AIRS level 2 products. While providing a basis for the validation of the φ-IASI inversion scheme, the retrieval exercise has also demonstrated (i) the NAST-I ability to accurately detect H2O fine-scale vertical features, and (ii) the good quality of the temperature and water vapour profiles from the ECMWF analysis.