Warm-Core Ring Driven Shelf/Slope Exchange

As the Gulf Stream heads north along the east coast of the United States it starts to destabilize and meander off the coast of New England. As these meanders pinch off, they form circular eddies, or “rings.” There are two types of rings that form – warm core rings that contain warm Sargasso Sea water and travel north into the cooler North Atlantic waters, and cold core rings that trap cold northern waters and move south into the Sargasso Sea. As the environmental conditions within rings are drastically different than the surrounding waters, these isolated habitats contain marine life that are unique from the surrounding waters. The ecosystems within a ring can survive as long as the ring does.

Because rings are so different from the surrounding environment, they can easily be spotted by satellites. In this nugget, a warm core ring is tracked as it is captured by a satellite and passes by two moorings in the OOI Coastal Pioneer Array. Examining the profiler data on these two moorings highlights what happens through the water column as a warm core ring passes by. Check out Zhang and Partida 2018 for a more in depth look at using these two datasets to analyze this Warm-Core Ring.

Water column temperature profiles can be compared with satellite images to visualize the movement of the warm core ring onto the continental shelf. Satellite Sea Surface Temperature data are from NOAA AVHRR satellite passes, and the diamonds are the locations of the Pioneer moorings. Within the profiler time series plots, profiles are highlighted that occurred at the same time as the satellite passes.

Plot Satellite SST Data Using Python Code. Code demonstrates how to access satellite Sea Surface Temperature data from individual NOAA AVHRR satellite passes from the Mid-Atlantic Regional Association Coastal Ocean Observing System (MARACOOS) and make plots.

Time series plots of water column profiles for the Central Offshore Profiler Mooring show the signature of the warm core ring as it passes by the mooring as concurrent changes in temperature, salinity, Colored Dissolved Organic Matter (CDOM), and oxygen.

Access Central Offshore Data

Disclaimer: data used in this example and provided in the .csv file were downloaded from the OOI on Nov. 4, 2019. The file format and/or contents could have changed if downloaded directly from OOI Net after this date.

Access from OOI Net:
CP02PMCO-WFP01-04-FLORTK000
CP02PMCO-WFP01-03-CTDPFK000
CP02PMCO-WFP01-02-DOFSTK000

Pull Data Using Python Code. Code demonstrates how to download data from two Pioneer profilers using the Machine-to-Machine (M2M) interface, calculate depth-binned hourly averages, and export the data as a .csv file.

Plot Wire-Following Profiler Data Using Matlab Code. Code demonstrates how to graph wire-following profiler data from a .csv file.

Central Offshore Profiler Mooring Data Review:
3-Wavelength Fluorometer
CTD
Dissolved Oxygen

Access Offshore Data

Disclaimer: data from the Offshore Profiler Mooring were downloaded with the Central Offshore Profiler Mooring from the OOI on Nov. 4, 2019. Data can be pulled and exported as a .csv file using the same Python code.

Access from OOI Net:
CP04OSPM-WFP01-04-FLORTK000
CP04OSPM-WFP01-03-CTDPFK000
CP04OSPM-WFP01-02-DOFSTK000

Plot Wire-Following Profiler Data Using Matlab Code. Code demonstrates how to graph wire-following profiler data from a .csv file.

Offshore Profiler Mooring Data Review:
3-Wavelength Fluorometer
CTD
Dissolved Oxygen

Time series plots of water column profiles for the Offshore Profiler Mooring show the signature of the warm core ring as it passes by the mooring as concurrent changes in temperature, salinity, Colored Dissolved Organic Matter (CDOM), and oxygen. Note that the Offshore Profiler Mooring travels to approximately 420 dbar but the graph was cropped at 130dbar to more easily compare with the Central Offshore Profiler.

Pioneer Array Central Offshore Profiler Mooring

Location: At the Continental Shelf-Slope Break off the coast of New England in the Mid-Atlantic Bight
Lat/Lon: 40.0963°N, 70.8789°W
Water Column Depth: 148m
Platform: Wire-Following Profiler
Instruments: All instruments are attached to the Wire-Following Profiler
3-Wavelength Fluorometer (FLORT-K)
CTD (CTDPF-K)
Dissolved Oxygen (DOFST-K)

Pioneer Array  Offshore Profiler Mooring

Location: On the Continental Slope Break the coast of New England in the Mid-Atlantic Bight
Lat/Lon: 39.9365°N, 70.8802°W
Water Column Depth: 453m
Platform: Wire-Following Profiler
Instruments: All instruments are attached to the Wire-Following Profiler
3-Wavelength Fluorometer (FLORT-K)
CTD (CTDPF-K)
Dissolved Oxygen (DOFST-K)

Graphics Credit: OOI Cabled Array program & the Center for Environmental Visualization, University of Washington

OOI Science Theme

Coastal Ocean Dynamics and Ecosystems (sub theme Shelf/Slope Exchange)

Essentials of Oceanography Textbook Sections

3.2 What features exist on continental margins?
5.6 How does seawater salinity vary at the surface and with depth?
7.4 What are the main surface circulation patterns in each ocean basin?

For more details, check out the full “Textbook Crosswalk”

Next Gen Science Standard Connections

HS-PS3-4. Plan and conduct an investigation to provide evidence that the transfer of thermal energy when two components of different temperature are combined within a closed system results in a more uniform energy distribution among the components in the system (second law of thermodynamics). Water temperatures changes as the warm core ring moves up the slope and into shelf waters.

Additional Resources

Naval Oceanographic Office North Atlantic Temperature map (updated 3x/week)
National Ocean Service – How fast is the Gulf Stream?
Jennifer Clark’s Gulf Stream Charts

Related Publications

Gawarkiewicz, G. and A.J. Plueddemann. 2020. Scientific rationale and conceptual design of a process-oriented shelfbreak observatory: the OOI Pioneer Array. Journal of Operational Oceanography 13(1):19-36. https://doi.org/10.1080/1755876X.2019.1679609.

Harden, B.E. 2020. Trends in Physical Properties at the Southern New England Shelf Break. JGR Oceans 125(2):e2019JC015784. https://doi.org/10.1029/2019JC015784.

Gangopadhyay, A., et al. 2019. An Observed Regime Shift in the Formation of Warm Core Rings from the Gulf Stream. Scientific Reports 9:12319. https://doi.org/10.1038/s41598-019-48661-9.

Chen, K., et al. 2018. Atmospheric and offshore forcing of temperature variability at the shelf break: Observations from the OOI Pioneer Array. Oceanography 31(1):72–79. https://doi.org/10.5670/oceanog.2018.112.

Gawarkiewicz, G., et al. 2018. The changing nature of shelf-break exchange revealed by the OOI Pioneer Array. Oceanography 31(1):60–70. https://doi.org/10.5670/oceanog.2018.110.

Zhang, W.G. and J. Partida, 2018. Frontal Subduction of the Mid‐Atlantic Bight Shelf Water at the Onshore Edge of a Warm‐Core Ring. JGR Oceans 123(11):7795-7818. https://doi.org/10.1029/2018JC013794.

Stanley, S. 2016. Gulf stream destabilization point is on the move. Eos 97. https://doi.org/10.1029/2016EO062455. Published on 08 November 2016.

Zhang, W.G. and G.G. Gawarkiewicz. 2015. Dynamics of the direct intrusion of Gulf Stream ring water onto the Mid‐Atlantic Bight shelf. Geophysical Research Letters 42(18):7687-7695. https://doi.org/10.1002/2015GL065530.