Editorial Type:
Article
Article Type:
Research Article

Jet Streaks in the Gulf Stream

Stephan D. Howden Graduate School of Oceanography, University of Rhode Island, Kingston, Rhode Island

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D. Randolph Watts Graduate School of Oceanography, University of Rhode Island, Kingston, Rhode Island

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Print Publication:
01 Aug 1999
DOI:
https://doi.org/10.1175/1520-0485(1999)029<1910:JSITGS>2.0.CO;2
Page(s):
1910–1924
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Abstract

Mesoscale alongstream speed changes of the Gulf Stream are diagnosed from an array of current meters at depths 400, 700, and 1000 m, near 68°W, during the development of steep [ratio of “amplitude” to “wavelength” O(1)] meanders. Speed maxima (jet streaks) are generally found between trough and crest axes in steep meanders with local speed minima near the trough and crest axes. Speed changes along streamlines can be quite dramatic. Speed changes along the jet axis, between jet streaks and local minima in excess of 0.60, 0.40, and 0.35 m s−1, are observed at depth 400, 700, and 1000 m, respectively. This is in comparison with peak speeds in a frontal coordinates system mean of 1.22, 0.67, and 0.28 m s−1, at depth 400, 700, and 1000 m, respectively, from a previous study.

The presence of the jet streaks can be explained kinematically as a superposition of the Gulf Stream and barotropic vortices. The development of these jet streaks in relation to the developing steep meanders differs from the canonical picture of jet streak/baroclinic wave development in the atmospheric jet stream in that the jet streaks in the Gulf Stream are predominantly fixed in place with respect to meanders as they steepen.

* Postdoctoral fellow for Universities Space Research Association, NASA/Goddard Space Flight Center, Greenbelt, Maryland.

Corresponding author address: Dr. Stephan D. Howden, NASA/Goddard Space Flight Center, Mailcode 971, Greenbelt, MD 20771.

Abstract

Mesoscale alongstream speed changes of the Gulf Stream are diagnosed from an array of current meters at depths 400, 700, and 1000 m, near 68°W, during the development of steep [ratio of “amplitude” to “wavelength” O(1)] meanders. Speed maxima (jet streaks) are generally found between trough and crest axes in steep meanders with local speed minima near the trough and crest axes. Speed changes along streamlines can be quite dramatic. Speed changes along the jet axis, between jet streaks and local minima in excess of 0.60, 0.40, and 0.35 m s−1, are observed at depth 400, 700, and 1000 m, respectively. This is in comparison with peak speeds in a frontal coordinates system mean of 1.22, 0.67, and 0.28 m s−1, at depth 400, 700, and 1000 m, respectively, from a previous study.

The presence of the jet streaks can be explained kinematically as a superposition of the Gulf Stream and barotropic vortices. The development of these jet streaks in relation to the developing steep meanders differs from the canonical picture of jet streak/baroclinic wave development in the atmospheric jet stream in that the jet streaks in the Gulf Stream are predominantly fixed in place with respect to meanders as they steepen.

* Postdoctoral fellow for Universities Space Research Association, NASA/Goddard Space Flight Center, Greenbelt, Maryland.

Corresponding author address: Dr. Stephan D. Howden, NASA/Goddard Space Flight Center, Mailcode 971, Greenbelt, MD 20771.

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