FY 1993

Energetics of gravitational adjustment for mesoscale chimneys

Hermann, A.J., and W.B. Owens

J. Phys. Oceanogr., 23(2), 346–371, doi: 10.1175/1520-0485(1993)023<0346:EOGAFM>2.0.CO;2 (1993)

The rates of energy flux out of newly formed circular patches of dense water (chimneys) are considered as a function of patch size on an f plane. The dense fluid resulting from a rapid deep convective process serves as a powerful reservoir of both mass and energy. Energy flux due to superinertial waves precedes mass flux. Both mass and energy are ultimately carried away from the local site of convection through baroclinic instability. Analytical and numerical methods are employed to investigate the relative amounts of potential energy radiated to the far field by either process, and the rates at which this is accomplished. An analytical solution is developed for the superinertial transients generated during linear, axisymmetric gravitational adjustment of a unit step. Initial energy decay by axisymmetric gravitational collapse is greater for a narrow chimney than for a wide one, but ultimately this is equaled and surpassed by the steady spreading of the wide chimney via its baroclinic breakup into smaller structures.