Mesoscale eddies of the Arctic Ocean

Abstract

Subsurface baroclinic eddies in the Arctic Ocean have a diameter of 10–20 km and are confined in depth between 50 and 300m. During the Arctic Ice Dynamics Joint Experiment (AIDJEX) in the central Beaufort Sea between March 1975 and May 1976, extensive information on eddy characteristics, statistics, and behavior was collected from four manned drifting ice camps. During this 14‐month period, 146 eddies were encountered, of which 19 were found to be repeated crossings, making a total of 127 separate eddies observed during this period. On the basis of the 1975–1976 AIDJEX data set, it is concluded that eddies are (1) prevalent in the Amerasia Basin of the Arctic Ocean and, in particular, the Beaufort Sea where they may occupy up to a quarter of the available surface area, (2) located in the depth range of 50–300 m (although a few deeper eddies are also present), (3) the second largest producers (32%) of kinetic energy found within the upper 200 m of the Beaufort Sea, and (4) predominantly anticyclonic in rotational tendency. These eddies apparently originate north of Point Barrow, Alaska, as a result of instability in the eastward flowing Alaskan Coastal Current and transfer seasonally varying water properties from the Chukchi Sea and Alaskan Shelf into the Arctic Ocean. They appear to translate in response to barotropic forcing over short time scales and, over longer time periods, move with the mean geostrophic field. The season of formation for an eddy may be identified by the anomalous thermal properties still residing in its core.