ON THE FORMATION AND SPREADING OF THE BASS STRAIT CASCADE

The Bass Strait cascade is a wintertime downwelling caused by cooling of the shallow waters of Bass Strait. During winter, a front separates the cold shelf water from the waters of the Tasman Sea. Continuous horizontal bands of downwelled water leading oceanward beneath the front imply that it can be transgressed near the bottom anywhere along its length. However, by far the greatest volume crosses at a breach at the northern end. Measured currents in eastern Bass Strait fit a predictable pattern: eastward toward the front. then as the front is approached, swinging north towards the breach. Flow northwards along the slope after downwelling is quantified using a simple analytic model. Cascade water found in the ''far-field'' was found only in small patches. One such patch was found to possess motion independent from the mean flow in which it was embedded.