Publication Date:
2022-05-26
Description:
Author Posting. © American Geophysical Union, 2020. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 125(8), (2020): e2019JC016033, doi:10.1029/2019JC016033.
Description:
A census of Gulf Stream (GS) warm‐core rings (WCRs) is presented based on 38 years (1980–2017) of data. The census documents formation and demise times and locations, and formation size for all 961 WCRs formed in the study period that live for a week or more. A clear regime shift was observed around the Year 2000 and was reported by a subset of authors (Gangopadhyay et al., 2019, https://doi.org/10.1038/s41598-019-48661-9). The WCR formation over the whole region (75–55°W) increased from an average of 18 per year during Regime 1 (1980–1999) to 33 per year during Regime 2 (2000–2017). For geographic analysis formation locations were grouped in four 5° zones between 75°W and 55°W. Seasonally, WCR formations show a significant summer maxima and winter minima, a pattern that is consistent through all zones and both temporal regimes. The lifespan and size distribution show progressively more rings with higher longevity and greater size when formed to the east of 70°W. The average lifespan of the WCRs in all four zones decreased by 20–40% depending on zones and/or seasons from Regime 1 to Regime 2, while the size distribution remained unchanged across regimes. The ring footprint index, a first‐order signature of impact of the WCRs on the slope, increased significantly (26–90%) for all zones from Regime 1 to Regime 2, with the highest percent increase in Zone 2 (70–65°W). This observational study establishes critical statistical and dynamical benchmarks for validating numerical models and highlights the need for further dynamical understanding of the GS‐ring formation processes.
Description:
The authors acknowledge financial support from NOAA (NA11NOS0120038), NSF (OCE‐0815679 and OCE‐1851242), and SMAST and UMass Dartmouth. G. G. was supported by NSF under Grant OCE‐1657853 as well as a Senior Scientist Chair from WHOI. We have benefitted from many discussions on Gulf Stream and WCR with Magdalena Andres, Andre Schmidt, Paula Fratantoni, Jon Hare, Wendell Brown, Kathy Donohue, Tom Rossby, Peter Cornillon, and Randy Watts.
Description:
2020-12-29
Keywords:
Gulf Stream
;
Warm Core Rings
;
Regime‐Shift
;
Lifespan of rings
;
size of rings
;
Ring Census
Repository Name:
Woods Hole Open Access Server
Type:
Article
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