Evaluation of spectroscopic databases of water vapor between 585 and 600 nm

Abstract

The water vapor absorption band between 585 and 600 nm is suitable for atmospheric water vapor column retrieval from satellite data because saturation effects are absent and water is the only significant structured absorber within this region. Accurate knowledge of the absorption spectroscopy is important for the retrieval as well as for assessing radiative forcing. Spectral databases for this wavelength region lack experimental validation by atmospheric observations. By means of a line-by-line radiative transfer model we simulate the direct solar radiation reaching the ground using different spectral databases. We compare simulated spectra with high resolution measurements made using a ground based Fourier transform spectrometer. Instrument effects are considered and residuals are assigned to line intensity errors as far as possible. A quality estimate of four different databases is provided and the consequences for satellite based instrumentations are discussed.