Nonlinear Processes in Geophysics www.nonlin-processes-geophys.net 1023-5809 1607-7946 9 1 2002 10.5194/npg-9-11-2002 http://www.nonlin-processes-geophys.net/9/11/2002/ http://www.nonlin-processes-geophys.net/9/11/2002/npg-9-11-2002.html http://www.nonlin-processes-geophys.net/9/11/2002/npg-9-11-2002.pdf 11 23 0000-00-00 Impulse exchange at the surface of the ocean and the fractal dimension of drifter trajectories D. M. Summers School of Mathematics and Statistics, Napier University, 219 Colinton Road, Edinburgh EH14 1DJ, UK An impulse-based model is developed to represent a coupling between turbulent flow in the atmosphere and turbulent flow in the ocean. In particular, it is argued that the atmosphere flowing horizontally over the ocean surface generates a velocity fluctuation field in the latter's near-surface flow. The mechanism for this can be understood kinematically in terms of an exchange of tangentially-oriented fluid impulse at the air-sea interface. We represent this exchange numerically through the creation of Lagrangian elements of impulse density. An indication of the efficacy of such a model would lie in its ability to predict the observed fractal dimension of lateral trajectories of submerged floats set adrift in the ocean. To this end, we examine the geometry of lateral tracer-paths determined from the present model.