 |
| Titel |
Spatial relationship between the atmospheric circulation and the precipitation measured in the western Swiss Alps by means of the analogue method |
| VerfasserIn |
P. Horton, M. Jaboyedoff, R. Metzger, C. Obled, R. Marty |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1561-8633
|
| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 12, no. 3 ; Nr. 12, no. 3 (2012-03-23), S.777-784 |
| Datensatznummer |
250010619
|
| Publikation (Nr.) |
 copernicus.org/nhess-12-777-2012.pdf |
|
|
|
|
|
| Zusammenfassung |
An adaptation technique based on the synoptic atmospheric circulation to
forecast local precipitation, namely the analogue method, has been
implemented for the western Swiss Alps. During the calibration procedure,
relevance maps were established for the geopotential height data. These maps
highlight the locations were the synoptic circulation was found of interest
for the precipitation forecasting at two rain gauge stations (Binn
and Les Marécottes) that are located both in the alpine Rhône
catchment, at a distance of about 100 km from each other. These two stations
are sensitive to different atmospheric circulations.
We have observed that the most relevant data for the analogue method can be
found where specific atmospheric circulation patterns appear concomitantly
with heavy precipitation events. Those skilled regions are coherent with the
atmospheric flows illustrated, for example, by means of the back trajectories
of air masses. Indeed, the circulation recurrently diverges from the
climatology during days with strong precipitation on the southern part of the
alpine Rhône catchment. We have found that for over 152 days with precipitation
amount above 50 mm at the Binn station, only 3 did not show a trajectory of a
southerly flow, meaning that such a circulation was present for 98% of the
events.
Time evolution of the relevance maps confirms that the atmospheric circulation
variables have significantly better forecasting skills close to the
precipitation period, and that it seems pointless for the analogue method to
consider circulation information days before a precipitation event as a
primary predictor. Even though the occurrence of some critical circulation
patterns leading to heavy precipitation events can be detected by precursors
at remote locations and 1 week ahead (Grazzini, 2007; Martius et al., 2008), time
extrapolation by the analogue method seems to be rather poor. This would
suggest, in accordance with previous studies (Obled
et al., 2002; Bontron and Obled, 2005),
that time extrapolation should be done by the Global Circulation Model, which
can process atmospheric variables that can be used by the adaptation method. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|