Nonlinear Processes in Geophysics www.nonlin-processes-geophys.net 1023-5809 1607-7946 8 1/2 2001 10.5194/npg-8-69-2001 http://www.nonlin-processes-geophys.net/8/69/2001/ http://www.nonlin-processes-geophys.net/8/69/2001/npg-8-69-2001.html http://www.nonlin-processes-geophys.net/8/69/2001/npg-8-69-2001.pdf 69 94 0000-00-00 Intergyre transport in a wind-driven, quasigeostrophic double gyre: An application of lobe dynamics C. Coulliette S. Wiggins Control and Dynamical Systems and Environmental Engineering Science, 107-81, Caltech, Pasadena, CA 91125 Control and Dynamical Systems, 107-81, Caltech, Pasadena, CA 91125 This research was supported by ONR Grant No. N00014-97-1-0071 We study the flow obtained from a three-layer, eddy-resolving quasigeostrophic ocean circulation model subject to an applied wind stress curl. For this model we will consider transport between the northern and southern gyres separated by an eastward jet. We will focus on the use of techniques from dynamical systems theory, particularly lobe dynamics, in the forming of geometric structures that govern transport. By "govern", we mean they can be used to compute Lagrangian transport quantities, such as the flux across the jet. We will consider periodic, quasiperiodic, and chaotic velocity fields, and thus assess the effectiveness of dynamical systems techniques in flows with progressively more spatio-temporal complexity. The numerical methods necessary to implement the dynamical systems techniques and the significance of lobe dynamics as a signature of specific "events", such as rings pinching off from a meandering jet, are also discussed.