Water line parameters from refitted spectra constrained by empirical upper state levels: Study of the 9500– [formula omitted] region

Abstract

A fitting technique is proposed which gives more reliable spectral line parameters for blended and very weak lines. The technique uses common upper state energies to fix frequencies in cases where these are poorly determined. Room temperature Fourier Transform absorption spectra of pure water vapour due to Schermaul et al. [The water vapour spectrum in the region 8600– 15 , 000 cm - 1 : experimental and theoretical studies for a new spectral line database I: laboratory measurements. J Mol Spectrosc 2001;208:32–42; The water vapour spectrum in the region 8600– 15 , 000 cm - 1 : experimental and theoretical studies for a new spectral line database I: laboratory measurements. J Mol Spectrosc 2002;211:169–78] recorded at several pathlengths are refitted. Parameters are obtained for over 10,700 transitions of H 2 O 16 covering the frequency region 9500– 14 , 500 cm - 1 . Only 73 of the lines remain unassigned. Comparisons with previous studies on water vapour absorption in this region suggest that the new parameters give a more consistent representation of the underlying spectrum.