 |
| Titel |
Temporal evolution of stable water isotopologues in cloud droplets in a hill cap cloud in central Europe (HCCT-2010) |
| VerfasserIn |
J. K. Spiegel, F. Aemisegger, M. Schöll, F. G. Wienhold, J. L. Collett, T. Lee, D. Pinxteren, S. Mertes, A. Tilgner, H. Herrmann, R. A. Werner, N. Buchmann, W. Eugster |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 12, no. 23 ; Nr. 12, no. 23 (2012-12-06), S.11679-11694 |
| Datensatznummer |
250011654
|
| Publikation (Nr.) |
 copernicus.org/acp-12-11679-2012.pdf |
|
|
|
|
|
| Zusammenfassung |
| In this work, we present the first study resolving the temporal evolution of
δ2H and δ18O values in cloud droplets
during 13 different cloud events. The cloud events were probed on a 937 m
high mountain chain in Germany in the framework of the Hill Cap Cloud
Thuringia 2010 campaign (HCCT-2010) in September and October 2010. The δ
values of cloud droplets ranged from −77‰ to −15‰
(δ2H) and from −12.1‰ to
−3.9‰ (δ18O) over the whole campaign.
The cloud water line of the measured δ values was
δ2H=7.8×δ18O+13×10−3, which
is of similar slope, but with higher deuterium excess than other
Central European Meteoric Water Lines. Decreasing δ values in the
course of the campaign agree with seasonal trends observed in rain in central
Europe. The deuterium excess was higher in clouds developing after recent
precipitation revealing episodes of regional moisture recycling. The
variations in δ values during one cloud event could either result from
changes in meteorological conditions during condensation or from variations
in the δ values of the water vapor feeding the cloud. To test which of
both aspects dominated during the investigated cloud events, we modeled the
variation in δ values in cloud water using a closed box model. We
could show that the variation in δ values of two cloud events was
mainly due to changes in local temperature conditions. For the other eleven
cloud events, the variation was most likely caused by changes in the isotopic
composition of the advected and entrained vapor. Frontal passages during two
of the latter cloud events led to the strongest temporal changes in both
δ2H (≈ 6‰ per hour) and
δ18O (≈ 0.6‰ per hour). Moreover, a
detailed trajectory analysis for the two longest cloud events revealed that
variations in the entrained vapor were most likely related to rain out or
changes in relative humidity and temperature at the moisture source region or
both. This study illustrates the sensitivity of stable isotope composition of
cloud water to changes in large scale air mass properties and regional
recycling of moisture. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|