Ocean Sciences Research Spotlight

Gulf Stream Destabilization Point Is on the Move

Westward migration of the wavelike Gulf Stream pattern could have big effects on ocean mixing and heat transport off the U.S. East Coast.

Source: Geophysical Research Letters

By

The mighty Gulf Stream current transports warm water out of the Gulf of Mexico and along the U.S. East Coast from Florida to North Carolina before it begins its arc across the deep Atlantic. After the Gulf Stream passes Cape Hatteras, N.C., it gradually forms distinctive patterns called meanders, wavelike crests and troughs that look like curves in a huge, winding river.

Researchers spot the point where the Gulf Stream current starts to meander.
A conceptual view of the Gulf Stream current (red) as it begins to meander after crossing the Deep Western Boundary Current (blue). The point where meandering begins is moving steadily westward, which may influence observations made from the container vessel (C/V) Oleander, from the Pioneer Array (green), and at Line W (yellow). Credit: M. Andres

In a new study, Andres reports that the location where the Gulf Stream meanders begin to amplify has migrated westward over the past 2 decades. Satellite, mooring, and shipboard observations of the current’s flow from 1993 to 2014 show that this “destabilization point” has shifted west at a rate of about 25 kilometers per year.

Gulf Stream meanders can create underwater cyclones and other features that disrupt and stir nearby currents. The author’s analysis suggests that the migration of the destabilization point has boosted the frequency of deep stirring events since 2008. The westward movement may also be related to recent warming of shallower water above the continental shelf in the Mid-Atlantic Bight.

The author hypothesizes that the cause of the migration could be related to interactions between the Gulf Stream and the Deep Western Boundary Current, which flows toward the equator and crosses beneath the Gulf Stream near Cape Hatteras. Future research could determine why the destabilization point is on the move and what its full implications, such as potential effects on marine ecosystems, will be. (Geophysical Research Letters, doi:10.1002/2016GL069966, 2016)

—Sarah Stanley, Freelance Writer

Citation: Stanley, S. (2016), Gulf stream destabilization point is on the move, Eos, 97, doi:10.1029/2016EO062455. Published on 08 November 2016.
© 2016. The authors. CC BY-NC-ND 3.0
  • davidlaing

    One has to wonder whether this is a linear or a cyclical event. Is there evidence for earlier westward migrations of the destabilization point? Why should it be assumed that such westward motion is a one-time event?

    • Environmental Progression

      Cyclical or not, the correct focus is outlook and impact. If the outlook is regression, than the westward shift is of little concern, if the outlook is continued state change, outcomes must be managed.

      • davidlaing

        We should certainly be vigilant. What troubles me is the tacit assumption that this is a monotonic event, and the cyclic possibility isn’t even mentioned.

        • FishOutofWater00 .

          There’s only evidence for the single event they describe. The tacit assumption is something you made up. The authors are describing what they found. They do not discuss cycles because they have not found evidence of cycles.

          • davidlaing

            No, the tacit assumption is in the fact that regression is not considered, which it should be in a proper analysis. I.e., the author should have considered both the possibility that the shift was permanent and unidirectional and the possibility that it was temporary and cyclic, and considered the implications of both possibilities. Not finding evidence of cyclic behavior is not necessarily evidence that a cycle doesn’t exist, and to be thorough, both options should be considered.

            It’s the old blind men and the elephant routine. It’s not enough just to look at a portion of a system. In order to understand what’s really going on, you need to look at the whole thing, or at least to allow the possibility that what you’re looking at might simply be one part of a bigger system. Otherwise, you may well come to a false conclusion as to “What’s causing this, anyway?”