The Oleander Project began in 1992 as an effort to routinely acquire high-resolution, upper-ocean velocity and temperature measurements utilizing the MV Oleander, a container vessel that each week makes a round-trip passage along the 1200 km route between Port Elizabeth, New Jersey, and Hamilton, Bermuda. The ship’s route crosses the Middle Atlantic Bight, Slope Sea, Gulf Stream, and Sargasso Sea in the western North Atlantic and the data are providing long-term views of ocean currents and heat transport in this very dynamic and climatically important region.
Temperature measurements began in 1977, when XBTs were launched monthly along the outbound Oleander route providing records of the cross-shelf temperature structure of the Middle Atlantic Bight shelf and the Slope Sea to the Gulf Stream North Wall. In following decades, several improvements were made in sampling:
- In 2009, XBT coverage was extended across the Gulf Stream and into the Sargasso Sea.
- In 2011, this program was partially automated using the Autonomous eXpendable Instrument System (AXIS), which now takes launches the probes along the ship’s route.
- In 2016, NOAA/AOML included the program into its High Density XBT Network increasing the spatial resolution to ~25 km.
Horizontal current measurements began in 1992 when the Oleander’s hull was outfitted with a 150 kHz Acoustic Doppler Current Profiler (ADCP). Its vertical range was limited to the upper 200 m, most early studies focused on the horizontal structure of currents and the power of repeated transects to build up a multi-year time series. Improvements in velocity measurements are also being realized:
- In 2005, a 75 kHz ADCP was installed, extending the depth range to ~600 m in the Sargasso Sea.
- In June 2018, the 75 kHz ADCP failed and was not able to be repaired.
- In 2019, a new ship was built in China and delivered to Bermuda, including two new ADCP units operating at different frequencies. A 38kHz unit to extend the profile depth to ~1000 m and a 150 kHz unit to provide higher resolution in the upper 200 m depth range and on the continental shelf. A hiatus in data acquisition was incurred during installation of the new equipment. The higher frequency unit had to be removed and returned to the factory for repairs.
- In 2020, the Covid-19 pandemic shut down access to the ship at a time when the AXIS unit was off for maintenance, the 150 kHz was being repaired, and the 38kHz unit was contaminated by bubbles.
- As of May 2021, the 150 KHz ADCP and TSG are operating normally, and monthly XBT missions have resumed. We are still troubleshooting the 38 kHz ADCP.
A Thermosalinograph (TSG) was installed by NOAA/AOML from 2001 – 2013 enabling underway measurements of surface temperature and salinity which are telemetered back to shore-based data centers. Oleander PIs have run this system since 2014.
Collectively, these ongoing measurements and technical enhancements are enabling studies of ocean structures that are changing with time: e.g. circulation, heat content, sea level, mixed layers, Gulf Stream and eddies.
The Oleander Project owes an enormous debt of gratitude to the Bermuda Container Line, now managed by Neptune Group Management Ltd., as well as to the CMV Oleander officers, engineers and crew.
Early funding for The Oleander Project was provided by NOAA and the U.S. Office of Naval Research (ONR). Since 1999, the Oleander Project has been supported by the U.S. National Science Foundation Grant numbers OCE-9819724, OCE-0241654, OCE-0825845 and presently OCE-1536851.