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| Titel |
Modelling and interpreting the isotopic composition of water vapour in convective updrafts |
| VerfasserIn |
M. Bolot, B. Legras, E. J. Moyer |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 13, no. 16 ; Nr. 13, no. 16 (2013-08-16), S.7903-7935 |
| Datensatznummer |
250085631
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| Publikation (Nr.) |
 copernicus.org/acp-13-7903-2013.pdf |
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| Zusammenfassung |
| The isotopic compositions of water vapour and its condensates have
long been used as tracers of the global hydrological cycle, but may
also be useful for understanding processes within individual
convective clouds. We review here the representation of processes that
alter water isotopic compositions during processing of air in
convective updrafts and present a unified model for water vapour
isotopic evolution within undiluted deep convective cores, with
a special focus on the out-of-equilibrium conditions of mixed-phase
zones where metastable liquid water and ice coexist. We use our model
to show that a combination of water isotopologue measurements can
constrain critical convective parameters, including degree of
supersaturation, supercooled water content and glaciation
temperature. Important isotopic processes in updrafts include kinetic
effects that are a consequence of diffusive growth or decay of cloud
particles within a supersaturated or subsaturated environment;
isotopic re-equilibration between vapour and supercooled droplets,
which buffers isotopic distillation; and differing mechanisms of
glaciation (droplet freezing vs. the Wegener–Bergeron–Findeisen
process). As all of these processes are related to updraft strength,
particle size distribution and the retention of supercooled water,
isotopic measurements can serve as a probe of in-cloud conditions of
importance to convective processes. We study the sensitivity of the
profile of water vapour isotopic composition to differing model
assumptions and show how measurements of isotopic composition at cloud
base and cloud top alone may be sufficient to retrieve key cloud
parameters. |
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