The hydrogen isotopic composition of water vapor entering the stratosphere inferred from high-precision measurements of δD-CH_4 and δD-H_2
Abstract
The hydrogen isotopic composition of water vapor entering the stratosphere provides an important constraint on the mechanisms for dehydration of air ascending through the tropical tropopause layer. We have inferred the annual mean hydrogen isotopic composition of water vapor entering the stratosphere (or δD-H_(2)O_0) for the mid to late 1990s based on high-precision measurements of the hydrogen isotopic compositions of stratospheric H_2 and CH_4 from whole air samples collected on the NASA ER-2 aircraft between 1996 and 2000 and remote observations of δD-H_2O from the FIRS-2 far infrared spectrometer. We calculate an annual mean value for δD-H_(2)O_0 of −653 (+24/−25)‰ relative to Vienna standard mean ocean water (VSMOW). Previous inferences from balloon-borne and spacecraft remote-sensing observations are ∼20‰ lighter than the value from this analysis. We attribute the difference to an underestimation of deuterium in the molecular H_2 reservoir in earlier work. This precise and more accurate value for the annual mean δD-H_(2)O_0 will be useful as a 1990's benchmark for detecting future changes in the details of the dehydration of air due to the impact of climate change on convection intensity, cloud microphysics, or tropical tropopause layer temperatures. In addition, we report a value for the total deuterium content in the three main stratospheric hydrogen reservoirs HDO, HD, and CH_(3)D of 1.60 (+0.02/−0.03) ppbv.
Additional Information
© 2004 American Geophysical Union. Received 24 July 2003; revised 18 December 2003; accepted 24 December 2003; published 9 April 2004. We thank Stephen Donnelly, Rich Lueb, and Verity Stroud for support of the ER-2 whole air sampling and methane measurements, and Nami Kitchen for assistance in the CalTech laboratory. We gratefully acknowledge support through grants to UC Berkeley from the NASA Atmospheric Chemistry, Modeling and Analysis Program (NAG-1-2191 and NAG-1-02083), the NASA Upper Atmosphere Research Program (NAG-2-1483), and the NSF Atmospheric Chemistry Program (ATM-9901463) and for a Packard Foundation Fellowship in Science and Engineering for K.A.B.; to UC Irvine from the NASA Earth System Science Fellowship for A.R. (NAGTA5-50226), the NASA EOS Validation award (NAG5-9955), the NASA Carbon Cycle Science award (NGT5-30409), an NSF major research instrumentation award (ATM-9871077), and a Keck Foundation instrument grant to UC Irvine; to Caltech from the Davidow Fund and General Motors Corporation (J.M.E.); for the Frederick Reines postdoctoral fellowship from Los Alamos National Laboratory (T.R.); and to NCAR from the NASA Upper Atmosphere Research Program and the National Science Foundation. The National Center for Atmospheric Research is operated by the University Corporation for Atmospheric Research under the sponsorship of the National Science Foundation.Attached Files
Published - 2003JD004003.pdf
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Additional details
- Eprint ID
- 35099
- Resolver ID
- CaltechAUTHORS:20121025-114129715
- NAG-1- 2191
- NASA Atmospheric Chemistry, Modeling and Analysis Program
- NAG-1-02083
- NASA Atmospheric Chemistry, Modeling and Analysis Program
- NAG-2-1483
- NASA Upper Atmosphere Research Program
- ATM- 9901463
- NSF Atmospheric Chemistry Program
- Packard Foundation Fellowship in Science and Engineering
- NAGTA5-50226
- NASA Earth System Science Fellowship
- NAG5-9955
- NASA EOS Validation award
- NGT5-30409
- NASA Carbon Cycle Science award
- ATM-9871077
- NSF
- Keck Foundation
- Davidow Fund
- General Motors Corporation
- Los Alamos National Laboratory (LANL)
- National Center for Atmospheric Research (NCAR)
- Created
-
2012-10-25Created from EPrint's datestamp field
- Updated
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2021-11-09Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences