Interannual and seasonal asymmetries in Gulf Stream Ring Formations from 1980 to 2019

Adrienne Silver,Jenifer Clark,Avijit Gangopadhyay,E Nishchitha S Silva,Glen Gawarkiewicz

doi:10.1038/s41598-021-81827-y

Adrienne Silver, Jenifer Clark + Show 3 more

Open Access

https://doi.org/10.1038/s41598-021-81827-y

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Abstract

As the Gulf Stream separates from the coast, it sheds both Warm and Cold Core Rings between 75^circ and 55^circ ,hbox {W}. We present evidence that this ring formation behavior has been asymmetric over both interannual and seasonal time-scales. After a previously reported regime-shift in 2000, 15 more Warm Core Rings have been forming yearly compared to 1980–1999. In contrast, there have been no changes in the annual formation rate of the Cold Core Rings. This increase in Warm Core Ring production leads to an excess heat transfer of 0.10 PW to the Slope Sea, amounting to 7.7–12.4% of the total Gulf Stream heat transport, or 5.4–7.3% of the global oceanic heat budget at 30^circ ,hbox {N}. Seasonally, more Cold Core Rings are produced in the winter and spring and more Warm Core Rings are produced in the summer and fall leading to more summertime heat transfer to the north of the Stream. The seasonal cycle of relative ring formation numbers is strongly correlated (r = 0.82) with that of the difference in upper layer temperatures between the Sargasso and Slope seas. This quantification motivates future efforts to understand the recent increasing influence of the Gulf Stream on the circulation and ecosystem in the western North Atlantic.

Highlights

The Gulf Stream carries more than half of the total annual oceanic heat transported toward subpolar regions in the northern h emisphere[1,2,3]
The Gangopadhyay et al.[4,5] studies raised a very important question regarding ring formation from the Gulf Stream—does the formation rate of Cold Core Rings to the south of the Gulf Stream exhibit similar temporal and geographic patterns to the formation of Warm Core Rings? Using a newly developed census for Cold Core Rings, we examine the temporal behavior of the formation rates for Cold Core Rings versus Warm Core Rings at both interannual and seasonal time-scales
Comparing the heat transport in regime 1 to regime 2 (Fig. 4a), it appears that the eddies transported an average of 0.124 PW more heat during regime 2 than in regime 1

Summary

Introduction

The Gulf Stream carries more than half of the total annual oceanic heat transported toward subpolar regions in the northern h emisphere[1,2,3]. Part of this heat is advected by both Warm and Cold Core Rings formed from the Gulf Stream meanders in the Slope and Sargasso Seas, respectively. Two recent studies by Gangopadhyay et al.[4,5] have shown that there has been a significant regime shift in terms of Warm Core Rings formed in the Gulf Stream between 75◦ and 55◦ W. The Gangopadhyay et al.[4,5] studies raised a very important question regarding ring formation from the Gulf Stream—does the formation rate of Cold Core Rings to the south of the Gulf Stream exhibit similar temporal and geographic patterns to the formation of Warm Core Rings? Using a newly developed census for Cold Core Rings, we examine the temporal behavior of the formation rates for Cold Core Rings versus Warm Core Rings at both interannual and seasonal time-scales

Methods

Results

Conclusion