Empirical retrieval of the atmospheric air mass factor (ERA) for the measurement of water vapour vertical content using GOME data

A new empirical technique for the fast retrieval of vertical concentrations of water vapour from the GOME uncalibrated spectra is described in detail. The ERA technique (Empirical Retrieval of Atmospheric air mass factor) makes maximum use of GOME's capability to measure atmospheric spectra over a broad wavelength range with high spectral resolution, by retrieving a normalisation factor for the water vapour concentrations directly from the data (oxygen slant column measurements). ERA results are compared to the ECMWF TCWV analysis (Total Column Water Vapour), showing good agreement.