Influence of bottom topography on the circulation at the continental shelf off northern Norway

Abstract

The three banks Sveinsgrunnen, Malangsgrunnen and Nordvestbanken, which lie off the coast of northern Norway, are separated by troughs. Synoptic hydrographic surveys and data from satellite-tracked buoys drogued in the mixed layer, show that the botton topography strongly influences the distribution of water masses and current pattern. Coastal water above the banks circulates in a clockwise direction, while Atlantic water intruding in the troughs circulates in a anticlockwise direction. This circulation pattern influences the transport and spreading of cod eggs from the spawning grounds which are sited between the banks and the coastline. The eggs are, for the most part, distributed throughout the Coastal water on the banks, while only small numbers are found in the Atlantic water in the troughs. The circulation in the investigated area probably favours mixing of the Coastal and Atlantic water masses. Moderately stratified concitions occur in the period from June to September. During this period, the influence of the bottom topography seems to be less pronounced. However, Atlantic water does flow into the trough Malangsdjupet during stratified conditions.