 |
| Titel |
The transport history of two Saharan dust events archived in an Alpine ice core |
| VerfasserIn |
H. Sodemann, A. S. Palmer, C. Schwierz, M. Schwikowski, H. Wernli |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 6, no. 3 ; Nr. 6, no. 3 (2006-02-28), S.667-688 |
| Datensatznummer |
250003515
|
| Publikation (Nr.) |
 copernicus.org/acp-6-667-2006.pdf |
|
|
|
|
|
| Zusammenfassung |
| Mineral dust from the Saharan desert can be transported across the Mediterranean
towards the Alpine region several times a year. When coinciding with snowfall,
the dust can be deposited on Alpine glaciers and then appears as yellow or red
layers in ice cores. Two such significant dust events were identified in an ice
core drilled at the high-accumulation site Piz Zupó in the Swiss Alps
(46°22' N, 9°55' E, 3850 m a.s.l.). From stable oxygen
isotopes and major ion concentrations, the events were approximately dated as
October and March 2000. In order to link the dust record in the ice core to the
meteorological situation that led to the dust events, a novel methodology based
on back-trajectory analysis was developed. It allowed the detailed analysis of the
specific meteorologic flow evolution that was associated with Saharan dust
transport into the Alps, and the identification of dust sources, atmospheric
transport paths, and wet deposition periods for both dust events. Differences
in the chemical signature of the two dust events were interpreted with respect
to contributions from the dust sources and aerosol scavenging during the
transport.
For the October event, the trajectory analysis indicated that dust deposition
took place during 13–15 October 2000. Mobilisation areas of dust were mainly
identified in the Algerian and Libyan deserts. A combination of an upper-level
potential vorticity streamer and a midlevel jet across Algeria first brought
moist Atlantic air and later mixed air from the tropics and Saharan desert
across the Mediterranean towards the Alps. The March event consisted of two
different deposition phases which took place during 17–19 and 23–25 March
2000. The first phase was associated with an exceptional transport pathway past
Iceland and towards the Alps from northerly directions. The second phase was
similar to the October event. A significant peak of methanesulphonic acid
associated with the March dust event was most likely caused by incorporation of
biogenic aerosol while passing through the marine boundary layer of the western
Mediterranean during a local phytoplankton bloom. From this study, we conclude
that for a detailed understanding of the chemical signal recorded in dust events
at Piz Zupó, it is essential to consider the whole transport sequence of
mineral aerosol, consisting of dust mobilisation, transport, and deposition at
the glacier. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|