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Field Test of Spectral Line Intensity Parameters For Tropospheric Water Vapor


We report the results of a field experiment designed to study atmospheric water vapor absorption in the visible and near-infrared spectral regions between 550 and 1000 nm. We carried out spectroscopic ground measurements of direct solar radiation in clear-sky atmosphere in Boulder, CO. The data with a spectral resolution of approximately 1 nm were analyzed using the Differential Optical Absorption Spectroscopy (DOAS) technique in five different absorption bands of water vapor. We show that this technique can reveal the broad band effects of errors and inconsistencies in absorption spectra information for the water molecule. Retrievals of column tropospheric water vapor from the field spectra were compared to simultaneous independent estimates from Global Positioning System (GPS) data and radiosonde soundings. The dataset is used to critically assess the widely used High-resolution Transmission Molecular Absorption Database (HI-TRAN) [Rothman et al., 1998]. The results indicate that line intensities in the 3n+d polyad centered at 820 nm are underestimated by 21 % with respect to the strong 3v polyad centered at 940 nm, while the 4n band at 720 nm shows agreement within the measurement accuracy of 3 %. Two weaker bands centered at 650 and 590 nm were found to be overestimated by about 8-10 %. The effect of the proposed corrections on the absorption of incoming solar flux for a clear sky atmosphere is estimated to be 0.6 W/m2 for an overhead Sun.

Article / Publication Data
Available Metadata
Accepted On
March 16, 2003
Fiscal Year
Publication Name
Journal of Geophysical Research
Published On
January 01, 2003
Print Volume
Print Number
Submitted On
September 16, 2002


Not available


Authors who have authored or contributed to this publication.

  • keith G. holub - Not Positioned Other
    Under Contract to NOAA/Global Systems Laboratory
    325 Broadway, Boulder, Colorado