Drifter observations of small-scale flows in the Philippine archipelago

Abstract

This article presents observations of near-surface current trajectories made with water-following drifters in the Philippine Archipelago. The data describe small-scale flows around obstacles and provide some snapshots of regional currents that both add insight into conceptual views of circulation on a variety of scales. The most interesting tracks are those collected in San Bernardino Strait, where the interaction of energetic tidal flows with small islands, seamounts, and headlands give rise to flows with vorticity and strain rate that can exceed 100f on scales < 1 km. The observations show some of the high Rossby number flows that challenge regional circulation models. Much of the data inform subgridscale motions that models must presently parameterize. © 2011 by The Oceanography Society.