Wind and the Surface Circulation of a Fjord

Abstract
An experiment has been carried out recently to investigate the relative effects of wind, tide, and river runoff on the circulation of the surface layer of a small fjord. Drogues were tracked with a radar set for several days at four locations. Data were recorded photographically and digitized for computer processing to produce the velocity and acceleration of each drogue along its track. Wind forcing was dominant. The river input was important too, causing large horizontal shears in the flow. Tidal effects appeared to be negligible. Frictional coupling between the surface layer and the water below appeared to be very small. A mechanism for the surface layer behavior is proposed with the layer nearly decoupled from the underlying water by a strong pycnocline. The basic assumptions of this mechanism applied to the data set yield an average drag coefficient of 1 to 2 × 10−3.