John Marshall

Cecil and Ida Green Professor of Oceanography, MIT

Localized convection in rotating stratified fluid

Localized convection in rotating stratified fluid.

(Whitehead, JA and Marshall, J and Hufford, GE), JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, vol. 101, no. C11, pp. pages, 1996.


We study the convective overturning of a rotating stratified fluid in the laboratory. Convection is induced from the surface of a salt-stratified fluid by the introduction of salty fluid over a circular area. The external parameters are buoyancy forcing of strength, B-0, applied over a circular area of radius R(s), the rotation rate as measured by f, ambient stratification N, and the depth H. The experiments are motivated by physical scaling arguments which attempt to predict the length and velocity scales of the convective chimney as it adjusts under gravity and rotation and breaks up through baroclinic instability. The scales of interest include the number, size, and typical speeds of the fragments of the broken chimney, the final depth of penetration of the convective mixed layer, and the total volume of convectively produced water. These scales are tested against the laboratory experiments and found to be appropriate. In this idealized problem we have found the depth of penetration depends only on the size and strength of the forcing and the ambient stratification encountered by the convection event; it does not depend explicitly on rotation. The implications of the work to deep water formation in the Labrador Sea and elsewhere are discussed. Finally, the study has relevance to the role and representation of baroclinic eddies in large-scale circulation of the ocean.

doi = 10.1029/96JC02322