Antarctic Peninsula mesoscale cyclone variability and climatic impacts influenced by the SAM

The frequency of mesoscale cyclones in the Western Antarctic Peninsula (WAP) region during 1991–94 is correlated with the Southern Hemisphere Annular Mode (SAM) index, most strongly during winter and spring. Also, during periods of positive SAM index polarity there is a shift in the storm tracks to favor more east‐bound trajectories, consistent with strengthening of circumpolar westerlies. The presence of mesoscale cyclones is associated with positive near‐surface‐air temperature anomalies in the WAP region year‐round, largest during winter.