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• 1. [Article] Statistical properties of near surface currents in the California coastal transition zone

  During the summers of 1987 and 1988, 77 near-surface satellite-tracked drifters were deployed in or near cold filaments near Point Arena, California (39ºN), and tracked for up to 6 months as part of the ...

  Citation × Citation Citation Abstract Copy Title: Statistical properties of near surface currents in the California coastal transition zone Author: Beardsley, R. C., Abbott, Mark R., Stanton, T., Stuart, D., Ramp, S., Brink, K. H., Niiler, Pearn P., Huyer, Adriana, 1945- During the summers of 1987 and 1988, 77 near-surface satellite-tracked drifters were deployed in or near cold filaments near Point Arena, California (39ºN), and tracked for up to 6 months as part of the Coastal Transition Zone (CTZ) program. The drifters had large drogues centered at 15 m, and the resulting drifter trajectory data set has been analyzed in terms of its Eulerian and Lagrangian statistics. The CTZ drifter results show that the California Current can be characterized in summer and fall as a meandering coherent jet which on average flows southward to at least 30ºN, the southern end of the study domain. From 39ºN south to about 33ºN, the typical core velocities are of O(300 km) and the current meanders have alongshore wavelengths of O(100–200 km) and onshore-offshore amplitude of O(100–200 km). The lateral movement of this jet leads to large eddy kinetic energies and large eddy diffusivities, especially north of 36ºN. The initial onshore-offshore component of diffusivity is always greater than the alongshore component in the study domain, but at the southern end, the eddy diffusivity is more isotropic, with scalar single particle diffusivity (Kxx + Kyy) of O(8 x 107 cm2 s-1). The eddy diffusivity increases with increasing eddy energy. Finally, a simple volume budget for the 1988 filament observed near 37ºN off Point Arena suggests that subduction can occur in a filament at an average rate of O(10 m d-1) some 200 km offshore, thus allowing the cold water initially in the filament core to sink below the warmer ambient water by the time the surface velocity core has turned back onshore. This process explains why satellite temperature and color imagery tend to “see” only flow proceeding offshore. Title: Statistical properties of near surface currents in the California coastal transition zone Author: Beardsley, R. C., Abbott, Mark R., Stanton, T., Stuart, D., Ramp, S., Brink, K. H., Niiler, Pearn P., Huyer, Adriana, 1945- During the summers of 1987 and 1988, 77 near-surface satellite-tracked drifters were deployed in or near cold filaments near Point Arena, California (39ºN), and tracked for up to 6 months as part of the Coastal Transition Zone (CTZ) program. The drifters had large drogues centered at 15 m, and the resulting drifter trajectory data set has been analyzed in terms of its Eulerian and Lagrangian statistics. The CTZ drifter results show that the California Current can be characterized in summer and fall as a meandering coherent jet which on average flows southward to at least 30ºN, the southern end of the study domain. From 39ºN south to about 33ºN, the typical core velocities are of O(300 km) and the current meanders have alongshore wavelengths of O(100–200 km) and onshore-offshore amplitude of O(100–200 km). The lateral movement of this jet leads to large eddy kinetic energies and large eddy diffusivities, especially north of 36ºN. The initial onshore-offshore component of diffusivity is always greater than the alongshore component in the study domain, but at the southern end, the eddy diffusivity is more isotropic, with scalar single particle diffusivity (Kxx + Kyy) of O(8 x 107 cm2 s-1). The eddy diffusivity increases with increasing eddy energy. Finally, a simple volume budget for the 1988 filament observed near 37ºN off Point Arena suggests that subduction can occur in a filament at an average rate of O(10 m d-1) some 200 km offshore, thus allowing the cold water initially in the filament core to sink below the warmer ambient water by the time the surface velocity core has turned back onshore. This process explains why satellite temperature and color imagery tend to “see” only flow proceeding offshore. Close