FY 1981

Hydrographic structure over the continental shelf of the southeastern Bering Sea

Kinder, T.H., and J.D. Schumacher

Chapter 4 in Eastern Bering Sea Shelf: Oceanography and Resources, D.W. Hood and J.A. Calder (eds.), Vol. 1, USDOC/NOAA/OMPA, 31–51 (1981)

We synthesize recent work conducted over this exceptionally broad (~500 km) shelf which generally has only slow mean flow (~2 cm/sec). Hydrographic structure is little influenced by this flow, but rather is formed primarily by boundary processes: tidal and wind stirring; buoyancy input from insolation, surface cooling, melting, freezing, and river runoff; and lateral exchange with the bordering oceanic water mass. Three distinct hydrographic domains can be defined using vertical structure to supplement temperature and salinity criteria. Inshore of the 50 m isobath, the coastal domain is vertically homogeneous and separated from the adjacent middle domain by a narrow (~10 km) front. Between the 50 m and 100 m isobaths, the middle domain tends toward a strongly stratified two-layered structure, and is separated from the adjacent outer domain by a weak front. Between the 100 m isobath and the shelf break (~170 m depth), the outer domain has surface and bottom mixed layers above and below a stratified interior. This interior has pronounced finestructure, as oceanic water intrudes shoreward from the weak haline front over the slope, and shelf water (middle domain) intrudes seaward across the 100 m isobath. These domains and their bordering fronts tend to persist through winter, although the absence of positive buoyancy often makes the middle shelf vertically homogeneous.