Atmos. Chem. Phys. Discuss., 5, 5373-5403, 2005
www.atmos-chem-phys-discuss.net/5/5373/2005/
doi:10.5194/acpd-5-5373-2005
© Author(s) 2005. This work is licensed under the
Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License.
Review Status
This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
High-precision isotope measurements of H216, H217, H218, and the Δ17O-anomaly of water vapor in the southern lowermost stratosphere
P. Franz1 and T. Röckmann1,2
1Max-Planck-Institute for Nuclear Physics, Heidelberg, Germany
2now at: Institute for Marine and Atmospheric Research Utrecht, Utrecht University, Utrecht, The Netherlands

Abstract. We report the first high-precision measurements of δ18O and Δ17O at high southern latitudes that can resolve changes in the isotopic composition of water vapor in the lowermost stratosphere and upper troposphere. A strong increase of δ18O with decreasing mixing ratio above the tropopause is found. Since also the water vapor mixing ratio decreases above the tropopause, the isotope data can be explained by mixing of relatively moist air from the tropopause with dry stratospheric air. However, the nature of dehyration process that produced this dry stratospheric, e.g., fast transport from the extratropical tropopause or mixing with air from the dehydrated polar vortex, cannot be clearly identified. The magnitude of the Δ17O-anomaly (departure from mass-dependent fractionation (MDF)) was below 2 for each datapoint, and the mean is consistent with a zero anomaly in lower level stratospheric water vapor. Various transport histories for the stratospheric data are discussed based on the mixing ratio and isotope data.

Citation: Franz, P. and Röckmann, T.: High-precision isotope measurements of H216, H217, H218, and the Δ17O-anomaly of water vapor in the southern lowermost stratosphere, Atmos. Chem. Phys. Discuss., 5, 5373-5403, doi:10.5194/acpd-5-5373-2005, 2005.
 
Search ACPD
Discussion Paper
    XML
    Citation
    Final Revised Paper
    Share