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| Titel |
The isotopic composition of precipitation from a winter storm – a case study with the limited-area model COSMOiso |
| VerfasserIn |
S. Pfahl, H. Wernli, K. Yoshimura |
| 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 ; 12, no. 3 ; Nr. 12, no. 3 (2012-02-14), S.1629-1648 |
| Datensatznummer |
250010651
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| Publikation (Nr.) |
 copernicus.org/acp-12-1629-2012.pdf |
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| Zusammenfassung |
| Stable water isotopes are valuable tracers of the atmospheric water cycle,
and potentially provide useful information also on weather-related processes.
In order to further explore this potential, the water isotopes H218O
and HDO are incorporated into the limited-area model
COSMO. In a first case study, the new COSMOiso model is
used for simulating a winter storm event in January 1986 over the eastern
United States associated with intense frontal precipitation. The modelled
isotope ratios in precipitation and water vapour are compared to spatially
distributed δ18O observations. COSMOiso very
accurately reproduces the statistical distribution of δ18O
in precipitation, and also the synoptic-scale spatial pattern and temporal
evolution agree well with the measurements. Perpendicular to the front that
triggers most of the rainfall during the event, the model simulates a
gradient in the isotopic composition of the precipitation, with high
δ18O values in the warm air and lower values in the cold
sector behind the front. This spatial pattern is created through an interplay
of large scale air mass advection, removal of heavy isotopes by precipitation
at the front and microphysical interactions between rain drops and water
vapour beneath the cloud base. This investigation illustrates the usefulness
of high resolution, event-based model simulations for understanding the
complex processes that cause synoptic-scale variability of the isotopic
composition of atmospheric waters. In future research, this will be
particularly beneficial in combination with laser spectrometric isotope
observations with high temporal resolution. |
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