Andrew J. Pershing,
Peter H. Wiebe,
James P. Manning, and Nancy J. Copley
The acoustic data from both surveys contained near-surface vertical bands of high volume backscatter. The frequency and intensity of these bands was strongly correlated with the magnitude of the current velocity. Significant upwelling and downwelling was observed in the ADCP records, and the acoustic bands often co-occurred in the downwelling zones. Simulations of particle distributions within idealized circulation cells, consistent with the acoustic and ADCP data, suggest that the acoustic bands are caused by aggregations of positively buoyant or upward-swimming scatterers. The circulation cells proposed could have an important effect on the ecology of the well-mixed region by aggregating upward-swimming zooplankton in near-surface patches.