A coupled atmosphere-ocean model is used to examine the role of air-sea interaction in climate variabilty. The coupled model consists of the GFDL AGCM coupled to a grid of independent mixed layer ocean models which is nearly global in extent. The ocean model simulates vertical processes which makes it appropriate for studying aspects of the climate system which operate on interannual timescales in the extratropics. At present, the coupled model has been integrated for 20 years and has been compared to a control simulation in which the AGCM has a repeating seasonal cycle of SST as boundary conditions.
Here we will focus on processes which create SST anomalies and how these anomalies influence the atmospheric circulation. The net surface heat flux is the dominant term in creating SST anomalies over most of the year except in fall when entrainment plays an equal or greater role over parts of the North Pacific and North Atlantic. This allows for the winter-to-winter recurrence of SST anomalies as thermal anomalies created by the net heat flux in late winter, remain below the mixed layer in summer and are then returned to the surface by entrainment in the following winter. Preliminary results indicate a southward shift in the SST gradient over the west Pacific in the coupled compared with the control simulation appears to supress the storm track and significantly alter the circulation at 500 mb.