Eddy Fynamics From Along-Track Altimetry

Satellite altimetry has reshaped our vision of the global eddy field, with long-lived, propagating coherent eddies now understood to be a major feature of the ocean circulation. Much of our understanding of the global eddy field is based on gridded altimetric products, which, being continuous in space and time, are highly convenient for analysis. Yet despite their successes, recent studies demonstrate that gridded products may substantially misrepresent the true eddy field, capturing only a portion of the true coherent structures while overestimating typical eddy sizes and underestimating their strengths. The misrepresentation of the oceanic eddy field by gridded altimetry—a consequence of the O(100) km decorrelation scales employed in the mapping process—has a host of practical implications, from degrading current predictions to confounding model/data intercomparisons to negatively impacting parameterization efforts. Perhaps more importantly, it hinders our ability to meaningfully test hypotheses on eddy dynamics that have been put forward by theoretical or modeling studies. There is a vast, and relatively untapped, resource for high-resolution eddy observations on a global scale. This is the along-track altimeter data prior to its incorporation into a mapping algorithm. As will be demonstrated in the course of this proposal, the along-track data, when suitably analyzed, can accurately resolve structures as small as 10 km in radius—thus offering the potential to substantially revise our view of oceanic eddy field and the processes that shape it. We propose an effort to unlock a wealth of information on the oceanic mesoscale latent in altimetric measurements by making novel use of the underlying along-track data. These techniques will be applied to two climatological important regions: the Gulf of Mexico, and the Lofoten Basin of the Nordic Seas. The sharing of open source software and value added-data sets is integral to the proposed effort, including relevant enhancements to an online eddy database previously created by the PIs.