OC4331-Mesoscale Oceanography
Final Project Summary

Topic Area

Generation of Beaufort Sea Submesoscale Vortices


Project Team Member(s)

LT John Simms, USN

LT Ron Shaw, USN


Major Findings

Over the four year experiment AIDJEX, helicopter airborne current profilers and CTD's observed 148 separate SCV's. SCV's are a fairly recent discovery and seem to be common in the west Arctic. SCV's cover roughly 20 to 30% of the Arctic Ocean and are the dominant cause of variability in density and velocity below the upper mixed layer. They are mostly anticyclonic with depths between 50m and 500m but are most numerous around 100m

The cores of SCV's in the Beaufort Sea almost always contain water with values of temperature and salinity different from those in the surrounding ocean. SCVs are not created in the Beaufort Sea but are created at the edge of the Arctic Ocean and advected into the central Arctic. They originate in summer time flow of warm water through the Bering Strait. The depth of the eddies correspond to the depth of the Pacific temperature maximum. The likely generation are is the Barrow Canyon due to its topography.


Water flowing northward across the Chukchi is concentrated into a strong current in the Barrow Canyon. The April-Aug mean flow is 0.25 m/s at 100 m depth. Similar flows exist in the winter. Barrow Canyon extends 250 km cutting across continental slope from the Chukchi to the Beaufort Sea. The region of most interest is upper end of Barrow Canyon known as the Barrow Sea Valley.


The flow is forced to the right side (southern) side of the canyon due to Coriolis. Cyclonic shear in the inviscid interior leads to postive potential vorticity. Because the fluid is inviscid, q is conserved and its value is set by upstream conditions. Inshore of the velocity maximum, the shear is anti-cyclonic. The potential vorticity of the shaded area has been reduced due to friction. Therefore, when the boundary current separates from the coast, SCVs are formed

The most important aspects of submesoscale vortices in the Beaufort Sea


References

DíAsaro, E. A.,Generation of Submesoscale Vortices: A New Mechanism, J. Geophys. Res.,93,6685-6693,1988.

DíAsaro, E. A.,Observations of Small Eddies in the Beaufort Sea, J. Geophys. Res.,93,6669-6684,1988.

Smith, W. O., Polar Oceanography, Academic Press San Diego CA, 1990.

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