Dynamic variability of the Gulf Stream front in the Carolina Capes
A theoretical investigation of the stability of a two-layer Gulf Stream model by a numerical technique is presented. This study is based on the hypothesis that the dynamic variability of the time-dependent baroclinic jet, which is assumed to be in geostrophic equilibrium to the lowest order, may be due to subinertial frequency disturbances propagating along the coast and acting as a time-dependent perturbation to the geostrophic jet. Our present model investigates the combined baroclinic-barotropic instability problem. The numerical results show that the baroclinic process transfers kinetic energy from the mean flow to the perturbation, while the barotropic process transfers kinetic energy from the perturbation to the mean flow. The former is more dominant than the latter, so the baroclinic process destabilizes the system, and a net transfer of kinetic energy is formed from the mean flow to the perturbation. The numerical results also show a release of potential energy from the mean flow to the perturbation, providing the energy necessary for the existence of a baroclinically unstable disturbance. The observational formation of the sinuous meander or folded-back filament on the Gulf Stream front is theoretically explained by the presence of southward/northward traveling disturbances with phase speeds less than the mean northward speed of the Gulf Stream, so that the manifestation of sense of propagation of the frontal feature is to the north.
- Research Organization:
- North Carolina State Univ., Raleigh (USA). Dept. of Marine, Earth and Atmospheric Sciences
- DOE Contract Number:
- FG09-85ER60376
- OSTI ID:
- 5112935
- Report Number(s):
- DOE/ER/60376-T3; ON: DE86015492
- Country of Publication:
- United States
- Language:
- English
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