ECN publicatie:
The Association Between the North Atlantic Oscillation and the Interannual Variability of the Tropospheric Transport Pathways in Western Europe
Orza, J.A.G.; Cabello Ganuza, M.; Galiano, V.; Vermeulen, A.T.; Stein, A.F.
Gepubliceerd door: Publicatie datum:
ECN Environment & Energy Engineering 11-6-2013
ECN publicatienummer: Publicatie type:
ECN-B--13-005 Boek(hoofdstuk)
Aantal pagina's: Volledige tekst:
17  Niet beschikbaar.

Gepubliceerd in: Langranian Modeling of the Atmospheric, 127, 141, Geophysical Monograph Series 200.

The variations in tropospheric transport pathways over a 20 year period, 1990– 2009, are studied at six locations in Europe. Three Atlantic (Lisbon, Mace Head, and Cabauw) and three Mediterranean sites (Málaga and Elche in the western part and Lecce in the central Mediterranean) are considered. The work is based on the identification of flow types at each location by robust cluster analysis of the trajectories, the assessment of temporal trends for each advection pattern, and subsequent quantification of the association, at the monthly scale, between the North Atlantic Oscillation (NAO) index (NAOi) and the frequency of occurrence of the identified flows. This exploratory study demonstrates the usefulness of the approach for specific locations in a context where synoptic circulation/weathertype classifications are usually used. A different number of advection pathways were identified at each location. Common features to all the sites were prevalence of westerly flows, strong seasonal variability, and association of the air flow types to known synoptic situations in both phases of the NAO. The degree of association varies strongly with latitude, location within the Mediterranean basin, and closeness to the action centers. Overall, flows reaching Mace Head and Cabauw present stronger association to the NAO, which is substantially reduced at lower latitudes and is not significant at Lisbon. Significant temporal trends are found for northerly flows at Mace Head andMálaga, associated to changes at the beginning of the study period that are also present in the NAOi time series. WSW flows at Mace Head exhibit a steady decreasing trend over the whole period.

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