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A new photolysis laser-induced fluorescence instrument for the detection of H2O and HDO in the lower stratosphere

St. Clair, J. M. and Hanisco, T. F. and Weinstock, E. M. and Moyer, E. J. and Sayres, D. S. and Keutsch, F. N. and Kroll, J. H. and Demusz, J. N. and Allen, N. T. and Smith, J. B. and Spackman, J. R. and Anderson, J. G. (2008) A new photolysis laser-induced fluorescence instrument for the detection of H2O and HDO in the lower stratosphere. Review of Scientific Instruments, 79 (6). Art. No. 064101. ISSN 0034-6748.

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We present a new instrument, Hoxotope, for the in situ measurement of H2O and its heavy deuterium isotopologue (HDO) in the upper troposphere and lower stratosphere aboard the NASA WB-57. Sensitive measurements of deltaD are accomplished through the vacuum UV photolysis of water followed by laser-induced fluorescence detection of the resultant OH and OD photofragments. The photolysis laser-induced fluorescence technique can obtain S/N>20 for 1 ppbv HDO and S/N>30 for 5 ppmv H2O for 10 s data, providing the sensitivity required for deltaD measurements in the tropopause region. The technique responds rapidly to changing water concentrations due to its inherently small sampling volume, augmented by steps taken to minimize water uptake on instrument plumbing. Data from the summer 2005 Aura Validation Experiment Water Isotope Intercomparison Flights (AVE-WIIF) out of Houston, TX show agreement for H2O between Hoxotope and the Harvard water vapor instrument and for HDO between Hoxotope and the Harvard ICOS water isotope instrument, to within stated instrument uncertainties. The successful intercomparison validates Hoxotope as a credible source of deltaD data in the upper troposphere and lower stratosphere.

Item Type:Article
Related URLs:
URLURL TypeDescription
St. Clair, J. M.0000-0002-9367-5749
Hanisco, T. F.0000-0001-9434-8507
Additional Information:©2008 American Institute of Physics. Received 7 September 2007; accepted 18 May 2008; published 16 June 2008. We thank the pilots and crew of the NASA WB-57, the logistical support of NASA Ames and NASA Johnson, and the engineering staff of the Harvard group for making the measurements possible. This work was supported by the NASA Upper Atmospheric Research Program.
Funding AgencyGrant Number
NASA Upper Atmospheric Research ProgramUNSPECIFIED
Subject Keywords:atmospheric measuring apparatus, fluorescence, heavy water, photolysis, stratosphere, troposphere, water
Issue or Number:6
Record Number:CaltechAUTHORS:CLArsi08
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11231
Deposited By: Archive Administrator
Deposited On:26 Jul 2008 02:42
Last Modified:09 Mar 2020 13:19

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