A current time series spanning from 1985 to 1996 in the Corsica Channel shows that seasonal and interannual variabilities are stable components of the circulation of the northern part of the Western Mediterranean Sea. For the first time these characteristics are related to the state of the North Atlantic Oscillation during winter. We have found that this large-scale control is mainly maintained through the air-sea interaction processes which take place in the Northern Basin. These results provide new elements for a consistent explanation of the major features of the basin circulation, such as the seasonal increase of the boundary current and Deep Water Formation. ¿ 1999 American Geophysical Union