The West Wind Drift feeds both the California and Alaska Currents, providing a pathway for exchange between the subarctic and subtropical gyres. Its bifurcation at the eastern boundary is known qualitatively but not particularly quantitatively. The relative proportions of waters returning poleward and those continuing equatorward is a matter of speculation due to a relatively sparse observational base incapable of resolving the space-time structure of the eastern boundary current formation. Seasonal and interannual changes in stratification in a broad region off the Pacific Northwest coast are recognized, but their causes and links to flow variation are largely unknown. Seagliders will operate year-round, occupying repeated hydrographic sections across the northern reaches of the California Current system. These measurements will characterize the seasonal evolution of the eastern boundary current system off the Washington coast.

Recent ONR-funded investigations have focused on regions bounded by progressively more complex topography (e.g. Arabian Sea, Japan/East Sea and Adriatic Sea) where orographic effects produce intense, small-scale atmospheric forcing. Small-scale wind- and buoyancy-forcing, combined with riverine input, complex bathymetry and proximity to the coastal boundary, support a wide variety of energetic fronts, filaments and eddies. These features have short temporal and spatial scales and can play critical roles in governing basin-scale circulation, cross-shelf transport, watermass transformation and subduction. Two cruises in the Northern and Central Adriatic Sea conducted quasi-synoptic, three-dimensional surveys of mesocale and submesoscale physical and optical variability, following their response to strong forcing events. During winter (February), sampling emphasized the response to episodic Bora wind events. Although springtime (May) measurement program was designed to sample during the Po River spring freshette, freshwater discharge rates were more than a standard deviation below the 12-year mean and winds remained weak throughout the survey period, leading to a study of weakly forced dynamics in a strongly stratified, shallow water regime. MORE »