The Western North Atlantic - A Lagrangian Viewpoint

This article is an overview of what we have learned in recent years about the circulation of the western North Atlantic by direct observation with Sofar floats. These instruments, like their progenitor the Swallow float, are in essence tagged water parcels which allow us to obtain an explicit description of fluid motion over a wide range of space and time scales. On time scales of months to years the wandering of floats from one region to another yields information on the large-scale motions of water masses. In this sense floats may be viewed as a branch of modern hydrography. On time scales of days and weeks the floats are very effective tracers of mesoscale oceanic motion.