April 2003 729 Simonnet Et Al.

• Main Authors: American Meteorological Society, Eric Simonnet, Roger Temam, Shouhong Wang
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: North Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.8.5150; http://www.atmos.ucla.edu/tcd/MG/./PREPRINTS/SGITW2.pdf

The time-dependent wind-driven ocean circulation is investigated for both a rectangular and a North Atlantic-- shaped basin. Multiple steady states in a 2-layer shallow-water model and their dependence on various parameters and other model properties were studied in Part I for the rectangular basin. As the wind stress on the rectangular basin is increased, each steady-state branch is destabilized by a Hopf bifurcation. The periodic solutions that arise off the subpolar branch have a robust subannual periodicity of 4--5 months. For the subtropical branch, the period varies between sub- and interannual, depending on the inverse Froude number F 2 defined with respect to the lower active layer's thickness H 2 .AsF 2 is lowered, the perturbed-symmetric branch is destabilized baroclinically, before the perturbed pitchfork bifurcation examined in detail in Part I occurs. Transition to aperiodic behavior arises at first by a homoclinic explosion off the isolated branch that exists only for sufficiently high wind stress.