Estimates of Geostrophic Surface Currents in the South Atlantic Bight

Abstract

The determination of long-term trends in the behavior of the Gulf Stream is critical to understanding the meridional heat transfer cycle and associated global climate change. In this study, in situ current measurements from cross-stream transects of an Acoustic Doppler Current Profiler (ADCP) were used in conjunction with satellite altimetry data to obtain accurate estimates of Gulf Stream surface geostrophic current within the South Atlantic Bight (SAB) between 1992 and 2004. Analysis of time series data reveals that the magnitude of the geostrophic flow varies seasonally and that the seasonally averaged velocity was greatest following the intense 1997–1998 El Niño. Because of the relatively small fluctuations in the Gulf Stream's path, our analysis provides a method for accurate, long-term measurements of Gulf Stream currents for this region of the SAB.

Keywords:

• Altimetry
• geostrophic surface currents
• Gulf Stream
• South Atlantic Bight

Acknowledgments

We would like to express our gratitude to the crew of the R/V Seward Johnson as well as to Joseph Jurisa, Katy Todora, and Steven Traynum for support in the laboratory. We would like to acknowledge Eelco Doornbos of the Delft University of Technology who provided helpful information on how to work within the format of the Radar Altimeter Database System. This research was supported in part by the NASA Physical Oceanography Program under Grant# NNG06GJ22G and by a South Carolina Space Grant Consortium Graduate Fellowship and NASA Grant# NNX08AO33G.