Amplified mid-latitude planetary waves favour particular regional weather extremes

Abstract

There has been an ostensibly large number of extreme weather events in the Northern Hemisphere mid-latitudes during the past decade. An open question that is critically important for scientists and policy makers is whether any such increase in weather extremes is natural or anthropogenic in origin. One mechanism proposed to explain the increased frequency of extreme weather events is the amplification of mid-latitude atmospheric planetary waves. Disproportionately large warming in the northern polar regions compared with mid-latitudes - and associated weakening of the north-south temperature gradient - may favour larger amplitude planetary waves, although observational evidence for this rema..