Effects of Background Rotation on Turbulent Line Plumes

Polar ice cap cracks open sporadically to form thin, long, narrow channels of open water, which are referred to as “leads.” When the open water is exposed to ambient air in the winter, surface freezing occurs, thus rejecting dense salty water into the ocean interior. Using a laboratory experiment that models leads as line buoyant plumes, it is demonstrated that the lead-induced motions are affected by the background rotation after descending to a depth of 3.2 (q0/Ω3)1/3, where q0 is the surface buoyancy flux per unit length and Ω is the rate of background rotation. The width of the plume at this point is 1.1 (q0/Ω3)1/3. After some time, the plume becomes unstable at its transverse edges and deflects sideways, thereby producing a strongly three-dimensional cyclonic spiraling flow pattern.