Circulation in Cross Sound, Alaska Continental Shelf Research

Cross Sound is located in southeast Alaska's Alexander Archipelago and extends ∼50 km eastward from the Gulf of Alaska to Icy Strait. Between May and August 2010, ten moorings were deployed at the entrances to Cross Sound and at key internal locations within the Sound. Instruments on each mooring measured current velocity and temperature; some also measured salinity. The tidal range in this region is large (>5 m), causing high current speeds (peak speed measured at 263 cm s−1), with a strong fortnightly signal. The flow predominantly follows the bathymetry westward from Icy Strait through Cross Sound and into the Gulf of Alaska. Moorings captured an estuarine exchange with outflow near the surface and inflow at depth. Earlier multi-year moorings demonstrated that synoptic variability in water properties is greater in spring and fall than over the summer season. In summer, during spring tides, the water column can mix to the bottom, delivering nutrients into the surface euphotic zone. When spring tides coincided with a strong wind event, bottom temperatures increased by > 1 °C over 3 days.