Item: Major avalanches in eastern pyrenees and north atlantic oscillation
Title: Major avalanches in eastern pyrenees and north atlantic oscillation
Proceedings: International Snow Science Workshop, Davos 2009, Proceedings
Authors: García, C., Peña, J.C., Martí, G., Oller, P., Martínez, Geological Institute of Catalonia, Barcelona, Spain, Meteorological Survey of Catalonia, Barcelona, Spain
Abstract: The number of major avalanche episodes registered in Eastern Pyrenees (north-east of the Iberian Peninsula) is correlated to the North Atlantic Oscillation (NAO). The NAO is one of the most important and recurrent patterns of atmospheric circulation variability in the Northern Hemisphere and affects the behaviour of surface temperatures and precipitation in Western Europe. The link between NAO and major avalanches activity is done by applying the cumulative NAO index proposed by Keylock in 2003. The link between avalanche activity and fluctuation of NAO index exists in Iceland, but is not detected in the French Alps. This study supposes an essay about what happens in areas further from the centres of the dipole of NAO. Results show a negative correlation between major avalanches activity in Eastern Pyrenees and NAO index (NAOi); it is even higher respect to the cumulative NAOi. The cumulative index NAO reflects the cumulative effect of snow accumulation in the starting zones as precipitation is affected by the fluctuation of NAO. Consequently, the sign of the correlation is negative since it has been demonstrated that increase of precipitation in Eastern Pyrenees is linked to negative values of NAOi. Nevertheless, results from the different avalanche forecasting regions in Eastern Pyrenees suggest a different response of avalanche activity respect to NAO, confirming Pyrenees as a complex snow-climate boundary. Finally, the time evolution of the major avalanche events for this index has been analyzed to observe possible changes in the avalanche activity in future, also taking into account the future NAO evolution suggested by some global warming scenarios.
Keywords: avalanches, north atlantic oscillation, eastern pyrenees
Digital Abstract Not Available