Tuesday, 11 January 2005
The leading mode of air-sea interaction in the North Atlantic region
The leading mode of air-sea interaction in the North Atlantic region is investigated by using a linear coupled model, which includes a five-layer primitive equation atmospheric model with synoptic eddy and low-frequency flow (SELF) feedback and an ocean mixed-layer model. It is shown that the NAO and the SSTA tripole are two related components of a leading coupled mode of air-sea interaction. NAO-like atmospheric circulation anomalies can produce tripole-like SST anomalies (SSTA) in the North Atlantic region and a NAO-like dipole with an equivalent barotropic structure over the North Atlantic can be excited by the SSTA tripole. The NAO-like response is primarily maintained by a positive SELF feedback. Without SELF feedback, this covarying pattern can not exist. However, without air-sea coupling, the NAO-like mode can still exist due to atmospheric internal dynamics.