Open House

El Niño's Footprints in the Polar Seas

Dr. Yuan's recent study summarizes what we have known about the Antarctic Dipole (ADP) mode in southern high latitudes and associated atmospheric circulation patterns. The Antarctic Dipole is a part of ENSO global anomaly and represents the largest ENSO temperature anomaly outside of the tropical Pacific. For warm events, warm temperature and less sea ice occur in the Pacific center of the dipole while cold temperature and more sea ice occurs in the Atlantic center of the dipole simultaneously. Anomalous temperature and sea ice persist a few seasons in high latitudes after tropical forcing reach its maximum. A persisting high-pressure center exists in the Bellingshausen Sea accompanying the dipole anomaly for warm events. The subtropical jet is enhanced and polar front jet is weakened in the Pacific. In the same time the strong jet stream swings polarward in the Atlantic. In addition, polarward mean heat flux is stronger in the Pacific while weaker in the Atlantic. The La Niña scenario is just a mirror image of the El Niño scenario (Figure 1).