Northern hemisphere storm tracks in strong AO anomaly winters

Abstract

Northern Hemisphere winter 300 hPa storm tracks/baroclinic waves and their energetics during strong Arctic Oscillation (AO) anomaly events are investigated. It is shown that during strong positive AO anomaly winters, the Atlantic storm track intensifies significantly and shifts northward and far downstream while Pacific storm track extends westward. Baroclinic waves over the Atlantic propagate along central North Atlantic during strong negative AO anomaly winters while during strong positive AO anomaly winters, waves over the Atlantic split into two branches. Distributions of the kinetic energy and energy conversions of different spatial scale over the storm track regions assume different characteristics for different AO phases. © 2008 Royal Meteorological Society.