MEASUREMENTS IN A TURBULENT PATCH IN A ROTATING, LINEARLY-STRATIFIED FLUID

A series of experiments is described in which a turbulent patch is gen erated locally by an oscillating grid positioned at one end and mid-de pth of a rotating channel filled initially with a linearly-stratified fluid, Measurements have been made of vertical density profiles throug h the patch both during sustained oscillations and following cessation of grid forcing. Temporal variations in patch size and structure, Tho rpe scales, mixedness parameter and available potential energy are ded uced from these measurements, and the effects thereon of varying the b ackground rotation rate, initial buoyancy frequency and grid action ar e investigated. For the growth phase of the patch, previous results ob tained by other workers are confirmed and extended. Because the rapid turbulent motions implied a large Rossby number, rotation was not impo rtant during this phase. During the decay phase, rotational effects ar e shown to become important, and the presence of rotation is found to retard the decay of both the mixedness and the Thorpe scales of the de nsity overturns within the patch. The work is novel in that measuremen ts of the patch parameters listed above have not previously been carri ed out in the presence of rotation. The results are relevant to studie s of such patches that have been observed in the ocean and atmosphere.