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Variability in HDO/H2O abundance ratios in the tropical tropopause layer

Nassar, R., Bernath, P.F., Boone, C.D., Gettelman, A., McLeod, S.D. and Rinsland, C.P. (2007) Variability in HDO/H2O abundance ratios in the tropical tropopause layer. Journal of Geophysical Research, 112 (112). D21305 - D21315. ISSN 0148-0227

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The dehydration of air in the tropical tropopause layer (TTL) and mechanisms for the entry of water vapor into the stratosphere are investigated by an analysis of ACE-FTS profiles of temperature, water vapor, and the ratio [HDO]/[H2O] expressed in δD notation. Month-to-month comparisons indicate greater seasonal variability than interannual variability between 25°S–25°N, thus comparisons are made between February, April, August, and October averages for the years 2004 and 2005 combined. The data indicate a pattern of seasonal variability which is clearer in the Northern Hemisphere tropics and a relationship between minimum temperature, minimum water vapor, and maximum HDO depletion, which exists beyond the estimated uncertainty in these values. The range of values observed for HDO depletion and comparisons to modeled Rayleigh distillation curves indicate an important contribution from convection in addition to gradual dehydration. Multiple factors including the shape of the δD profiles suggest that a likely mechanism for the convective influence is the lofting of ice particles in the tropical troposphere.

Item Type: Article
Institution: The University of York
Academic Units: The University of York > Chemistry (York)
Depositing User: York RAE Import
Date Deposited: 22 Apr 2009 09:36
Last Modified: 22 Apr 2009 09:36
Published Version: http://dx.doi.org/10.1029/2007JD008417
Status: Published
Publisher: Agu American Geophysical Union
Identification Number: 10.1029/2007JD008417
URI: http://eprints.whiterose.ac.uk/id/eprint/6669

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