On the Probability that a Gulf Stream Meander Crest Detaches to Form a Warm Core Ring

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  • 1 Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island
  • | 2 River Falls, Wisconsin
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Abstract

Eight years of Gulf Stream data were examined to determine the percentage of meander crests that give rise to warm core rings. Because of cloud cover in many of the satellite images it was not possible to associate a specific meander crest with each warm core ring formed, nor was it possible to follow each meander crest from the point at which its amplitude was first detectable to the point at which it left the study area, was absorbed by another meander, or split to form two meanders. Despite these problems, a lower bound of 0.24 could be placed on the probability that a meander crest detaches to form a warm core ring. This was obtained by considering all disturbances in the path of the Gulf Stream that could be tracked over a several day period. If consideration is restricted to disturbances with a length scale the size of warm core rings or larger, the probability of formation increases to 0.40. The authors argue that this is a more interesting number in that the wavelength of the meanders observed rarely (less than 20% of the time) increased by more than 50% of their initial value; hence only ring-scale meander crests can result in warm core rings, of these more than 40% do. Finally, it could be argued that the numbers for troughs forming cold core rings are similar.

Abstract

Eight years of Gulf Stream data were examined to determine the percentage of meander crests that give rise to warm core rings. Because of cloud cover in many of the satellite images it was not possible to associate a specific meander crest with each warm core ring formed, nor was it possible to follow each meander crest from the point at which its amplitude was first detectable to the point at which it left the study area, was absorbed by another meander, or split to form two meanders. Despite these problems, a lower bound of 0.24 could be placed on the probability that a meander crest detaches to form a warm core ring. This was obtained by considering all disturbances in the path of the Gulf Stream that could be tracked over a several day period. If consideration is restricted to disturbances with a length scale the size of warm core rings or larger, the probability of formation increases to 0.40. The authors argue that this is a more interesting number in that the wavelength of the meanders observed rarely (less than 20% of the time) increased by more than 50% of their initial value; hence only ring-scale meander crests can result in warm core rings, of these more than 40% do. Finally, it could be argued that the numbers for troughs forming cold core rings are similar.

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