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| Titel |
Using HDO-HHO correlations to examine stratospheric chemistry and transport processes |
| VerfasserIn |
Jörg Steinwagner, Thomas Röckmann, Gabriele P. Stiller |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250058113
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| Zusammenfassung |
| The chemical processing of hydrogen in the stratosphere is to large degree a closed system
where hydrogen is cycled between the main species H2O, CH4 and H2. The analogue is true
for deuterium D and the deuterated species HDO, CH3D and HD. Strong correlations exist
between the different species and their deuterated isotopologues. This makes it possible to
examine the stratospheric hydrogen budget by examining the correlation of the global
distributions of stratospheric deuterated (HDO) and non-deuterated water (HHO). Using
satellite measurements made with the MIPAS instrument on Envisat provides a global view.
Our findings support to a large extent a linear relationship between HDO and HHO that can
be inferred from basic assumptions found in the literature (McCarthy et al., 2004).
Deviations from this linear relationship exist at all latitudes. In the tropics we observe
deviations that are linked to the tape recorder (Mote et al., 1996). At latitudes between
+/-[10° 70°] seasonal deviations are localized in certain altitudes at around 25 km,
pointing to the existence of a small maximum of roughly 5% in molecular hydrogen
under summer conditions. Large deviations from the linear relationships are also
observable in the winter months over Polar regions. During descent mesospheric air from
altitudes above 55 km is transported downwards to altitudes around 40 km, where
it partly mixes with upper stratospheric air. Such intrusions are clearly visible in
correlations of deuterated and non-deuterated species because photolysis as the
major sink process for water in the mesosphere differently impacts different water
isotopologues, i.e. yields enrichment in HDO (Miller et al., 2000, Sandor et al., 2003).
However, a close examination of the intrusions over the South Pole reveals a layer
between the upper stratospheric and lower mesospheric air where HDO is being
destroyed and at the same time the probed air mass gets depleted in deuterium. |
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