TUNABLE DIODE LASER MEASUREMENTS OF INTENSITIES AND AIR-BROADENED HALFWIDTHS OF THE $\nu_{2}$ BAND OF HDO: RESULTS AND THEIR APPLICATION TO THE ANALYSIS OF STRATOSPHERIC SOLAR ABSORPTION SPECTRA
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Date
1984
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Publisher
Ohio State University
Abstract
The first spectroscopic measurements of the D/H ratio in stratospheric water vapor have been derived from an analysis of stratospheric solar absorption spectra recorded near sunset with the balloon-borne $0.02-cm^{-1}$ resolution University of Denver and the aircraft-borne $0.06-cm^{-1}$ resolution NCAR interferometer systems and from laboratory spectra of HDO obtained at NOAA/NESDIS with a tunable diode laser system and a D-enriched sample of water vapor. The results have been obtained from measurements of the absorption of isolated lines of the $\nu_{2}$ bands of $H_{2}O$ and HDO in the atmospheric spectra. The laboratory data were analyzed to determine absolute intensities and air-broadened halfwidths for the HDO lines. Parameters are presented for the 13 HDO lines which are in the 1469 to $1514 cm^{-1}$ region. The balloon-borne measurements indicate a D/H ratio, normalized to the reference value of 158 atomic parts per million of Standard Mean Ocean Water (SMOW), which increases from 0.55 near 18 km to 0.67 at 29 km. The aircraft measurements provide additional evidence for a large depletion in the D content of stratospheric water vapor. The same data sets have also been used to measure stratospheric $CH_{4}$. Within the experimental uncertainties, the changes in the $H_{2}O, HDO$, and $CH_{4}$ mixing ratios with altitude inferred from the balloon spectra are consistent with the hypothesis that these species are coupled in the stratosphere through the oxidation of $CH_{4}$.
Description
Author Institution: NASA Langley Research Center; Department of Physics, University of Denver; Department of Physics, College of William and Mary; NOAA/NESDIS, FOB \#4, E/RA21, College of William and Mary; National Center for Atmospheric Research, College of William and Mary