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Field Measurements of Water Vapor Continuum Absorption In The Visible and Near-infrared


We carried out a spectroscopic field experiment designed to measure water vapor continuum absorption in the visible and near-infrared spectral regions. Atmospheric spectra at ~1 nm resolution were recorded using direct sunlight at high solar zenith angles during sunrise. Simultaneously radiosonde soundings and a network of geodetic Global Positioning System (GPS) receivers were deployed to constrain the water vapor amount along the absorption path. The solar spectra were analyzed using the Differential Optical Absorption Spectroscopy technique, while the GPS and radiosonde observations were used as input data to a line-by-line radiative transfer model to compute theoretical differential absorption spectra. The difference between the measurements and the simulated spectra provides information regarding the additional absorption owing to the H2O continuum. The data are compared to predictions of the widely used Clough-Kneizys-Davies continuum model as well as with theoretically derived spectra of water dimer. The results show that continuum absorption contributes significantly to solar absorption even in highly saturated H2O bands. The comparisons provide the needed observations to improve future continuum parameterizations.

Article / Publication Data
Available Metadata
Accepted On
December 24, 2003
Fiscal Year
Publication Name
Journal of Geophysical Research Atmospheres
Published On
April 27, 2004
Publisher Name
Amer Geophysical Union
Print Volume
Print Number
Submitted On
March 11, 2003


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