The Alaska Coastal Current (ACC) is a narrow (<50 km wide) high-speed flow extending over the shelf from the northern Gulf of Alaska to the Aleutian Islands. The ACC is forced by a combination of the upper ocean baroclinity associated with freshwater runoff, and the prevailing cyclonic winds (downwellling favorable in the coastal zone). There exist a variety of outstanding issues regarding the forcing and response of the ACC. Perhaps the primary issue concerning the ACC involves the relative contributions of the runoff and the local winds to its mean structure and transport. Another important topic relates to the causes of cross-shelf exchanges, and their variability, in various regions of the Gulf. It is also unclear the degree to which the ACC interacts with the sub-arctic gyre, a deeper circulation related mostly to basin-scale oceanic processes. Finally, the potential predictability of the ACC on seasonal and longer time scales is uncertain, given prescribed atmospheric forcing.

These issues are addressed, to the extent possible, using past oceanographic observations, and atmospheric forcing estimated from the NCEP/NCAR Reanalysis. Much more detailed and extensive oceanographic observations are just beginning to be collected in the Gulf of Alaska as part of a project funded by the Global Ocean Ecosystems Dynamics (GLOBEC) Program. Early results from this work are presented, with the objective of further pursuing the mechanisms controlling the ACC.