Statistical Connections Between Extratropical Storminess Variability And Teleconnection Patterns

This study relates the extratropical storminess in the Northern Hemisphere during winter to the large scale flow using various regression models. Five teleconnection patterns were found to be statistically significant factors at the 5 percent level for storminess in the Euro-Atlantic region: the North Atlantic Oscillation (NAO), the East Atlantic pattern, the Scandinavian pattern, the East-Atlantic/Western-Russia pattern and the Polar/Eurasian pattern. In the North Pacific the dominant factor is found to be the Pacific North American (PNA) pattern. Furthermore, the relationship between teleconnection patterns and storminess can to a large extent be accounted for by a basic relation between storminess and the local mean SLP but with a few notable exceptions. In particular the East Atlantic pattern is identified as an important non-local factor for storminess over the Labrador Sea and the PNA pattern as an important non-local factor for storminess north of the Aleutian low. It will also be shown that the seriality of the synoptic lows in the northern midlatitudes is intimately linked with the teleconnection patterns. This is of particular relevance to regional climate and extreme events over Europe. Finally, we find that observed key relations between storm track seriality and several teleconnection patterns based are poorly represented in a GCM.