Atmospheric GCM response to an idealized anomaly of the Mediterranean sea surface temperature

Abstract

The atmospheric response to an idealized 2 K cooling of the Mediterranean Sea is studied in a general circulation model (GCM). In the downstream region, from the eastern Mediterranean basin to the whole Asian continent (following the sub-tropical jet-stream), a baroclinic response is produced with high pressure near the surface and low pressure in the upper layers. It is the direct response to the Mediterranean cooling and it needs only a few days to be established. Teleconnections with strong zonal characteristics are found following the sub-tropical jet-stream to the North Pacific and North America, propagating further across the North Atlantic towards Northern Europe. Two remarkable remote features are the deepening of the Aleutian Low in the North Pacific and the weakening of the Icelandic Low in the North Atlantic. These two teleconnections form and grow in several days in the North Pacific and several tens of days in the North Atlantic. Both have a quasi-barotropic vertical structure. It is believed that they are the consequence of complex interactions between the mean flow and the transient eddies in the atmosphere. © Springer-Verlag 2006.