The Oleander Project: High-resolution observations of the dynamic ocean between New Jersey and Bermuda

Woods Hole Oceanographic Institution, Woods Hole MA

Investigators

Abstract

For nearly three decades, a commercial container vessel, CV Oleander, has served as a volunteer oceanographic observing ship during weekly round-trip voyages between Port Elizabeth, NJ and Hamilton, Bermuda. The vessel’s route crosses the Mid Atlantic Bight (MAB) shelf and slope as well as the Gulf Stream and Sargasso Sea – a diverse set of regions that bring together subpolar and tropical waters and critically influence ocean circulation, heat transport, biological productivity and the marine carbon cycle in the western North Atlantic. Measurements made from the ship include current velocity from Acoustic Doppler Current Profilers (ADCP) and temperature from expendable bathythermographs (XBTs) and thermosalinograph. The most recent vessel replacement, however, necessitated changes in the installations of the oceanographic instrumentation and subsequent reduction in data return from the ship-mounted ADCPs. This project is focused on resolving the instrument performance issues and returning the Oleander to routine return of oceanographic data. Observations of partial pressure of carbon-dioxide (pCO2) are also made in-line with the theromosalinograph and there is a continuous plankton recorder for sampling plankton. This project will bring the newest Oleander’s scientific sensors online, and to continue and enhance the in situ measurements made possible by this commercial vessel’s regular service along a single route. These measurements are essential for studies of ocean circulation, heat transport, biological productivity and the marine carbon cycle in the western North Atlantic. Interannual to decadal variability in the Gulf Stream system has both regional and basin-wide implications. Gulf Stream meandering impacts exchange processes with surrounding waters. In addition, climate models point to rapid change in the Atlantic Meridional Overturning Circulation (AMOC), whose warm limb is carried within the Gulf Stream, and suggest that AMOC variability also drives changes observed on the shelf and coast. To understand the underlying processes and to validate or refute the model-based hypotheses, there is a need for in situ multidecade records of the Gulf Stream and surrounding waters. The Oleander Line with its coverage of shelf, slope, Gulf Stream and Sargasso waters is well-suited to directly measure fluxes associated with the AMOC and to compare with AMOC estimates from other latitudes to examine meridional coherence. Increased understanding of the drivers of both the long-term changes and the event-scale processes on the shelf and slope off the Northeast US has implications for the phenology and health of the shelf ecosystems along the highly populated coast with commercially important fisheries. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.