Scandinavian pattern and its climatic impact

Maintenance mechanisms of the Scandinavian teleconnection pattern and its possible impact on the Eurasian climate are investigated on the basis of long-term monthly data. Its upstream portion over the North Atlantic is forced and maintained by feedback forcing from transient eddies migrating along the nearby storm track, with an additional contribution from incoming Rossby wave activity from further upstream. The primary anomaly centre over the Scandinavian Peninsula and the downstream portion of the pattern manifest themselves basically as Rossby waves propagating towards central Siberia and east Asia, under the modest feedback forcing from transient eddies. The pattern shows apparent seasonality in its dynamical properties, including the wave-train orientation and wavelength, under the seasonally varying transient-eddy feedback forcing and waveguide structure for Rossby waves. In cold seasons, the positive phase of the pattern causes cold-air accumulation over a vast area extending from western Siberia to the regions around Lake Baikal and Lake Balkhash, while giving rise to decreased precipitation over northeastern Europe, western Siberia and some of the Arctic coastal regions. The pattern also changes the North Atlantic sea surface temperature differently between autumn and winter. Copyright (c) 2007 Royal Meteorological Society.