The “Warm-Arctic/Cold-continents” pattern during 1901–2010

The “Warm-Arctic/Cold-continents” (WACC) winter weather pattern is investigated using the European Centre for Medium-Range Weather Forecasts 20th Century reanalysis data (ERA20C) spanning 1901–2010. Both the 1920–1940 and 1990–2010 periods are characterized by Arctic amplification (AA) and mid-latitude continental cooling, although the Arctic warming signal for 1990–2010 is twice as strong as that for 1920–1940. Significant weakening in the mid-latitude polewards temperature gradient and zonal wind, wavier upper-level flow character, and strong regional blocking frequency/intensity changes are also detected during both AA periods. These results based on statistical analyses highlight the possible role of AA in affecting mid-latitude weather patterns, but further work is needed to quantify the influence of AA on particular mid-latitude dynamical features.