Observations of a Pribilof eddy

Abstract

Eddies along the eastern shelf-break of the Bering Sea play an important role in the physics, chemistry, and biology of the region. Eddy activity in this region is particularly strong near the major shelf-break canyons during the spring months, likely influencing the spring bloom. Spring eddy activity is negatively correlated with the North Pacific Index, a measure of the strength of the Aleutian Low. A strong Aleutian Low (negative NPI) is related to a strong sub-polar gyre, suggesting that spin-up of the gyre results in more eddy activity in this region. In situ data from an eddy sampled near Pribilof Canyon in 1997 suggest that these eddies can carry water from the outer shelf into the basin. Drifters rotating around the eddy at different radii exhibited differing rotation periods suggesting that the eddy was not rotating in solid body rotation. Thus horizontal exchange of water within the eddy may result in the excess nutrients and fresher water within the core of the eddy exchanging with the basin over time, influencing chlorophyll-a distributions throughout the summer months.