Silver
Adrienne M.
Silver
Adrienne M.
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ArticleSpatial variability of movement, structure, and formation of Warm Core Rings in the Northwest Atlantic Slope Sea(American Geophysical Union, 2022-08-16) Silver, Adrienne M. ; Gangopadhyay, Avijit ; Gawarkiewicz, Glen G. ; Andres, Magdalena ; Flierl, Glenn R. ; Clark, JeniferGulf Stream Warm Core Rings (WCRs) have important influences on the New England Shelf and marine ecosystems. A 10-year (2011–2020) WCR dataset that tracks weekly WCR locations and surface areas is used here to identify the rings' path and characterize their movement between 55 and 75°W. The WCR dataset reveals a very narrow band between 66 and 71°W along which rings travel almost due west along ∼39°N across isobaths – the “Ring Corridor.” Then, west of the corridor, the mean path turns southwestward, paralleling the shelfbreak. The average ring translation speed along the mean path is 5.9 cm s−1. Long-lived rings (lifespan >150 days) tend to occupy the region west of the New England Seamount Chain (NESC) whereas short-lived rings (lifespan <150 days) tend to be more broadly distributed. WCR vertical structures, analyzed using available Argo float profiles indicate that rings that are formed to the west of the NESC have shallower thermoclines than those formed to the east. This tendency may be due to different WCR formation processes that are observed to occur along different sections of the Gulf Stream. WCRs formed to the east of the NESC tend to form from a pinch-off mechanism incorporating cores of Sargasso Sea water and a perimeter of Gulf Stream water. WCRs that form to the west of the NESC, form from a process called an aneurysm. WCRs formed through aneurysms comprise water mostly from the northern half of the Gulf Stream and are smaller than the classic pinch-off rings.
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ArticleA survival analysis of the gulf stream warm core rings(American Geophysical Union, 2020-10-14) Silva, E. Nishchitha S. ; Gangopadhyay, Avijit ; Fay, Gavin ; Welandawe, Manushi K. V. ; Gawarkiewicz, Glen G. ; Silver, Adrienne M. ; Monim, Mahmud-Ul-Hasan ; Clark, JeniferSurvival of Gulf Stream (GS) warm core rings (WCRs) was investigated using a census consisting of a total of 961 rings formed during the period 1980–2017. Kaplan‐Meier survival probability and Cox hazard proportional models were used for the analysis. The survival analysis was performed for rings formed in four 5° zones between 75° W and 55° W. The radius, latitude, and distance from the shelf‐break of a WCR at formation all had a significant effect on the survival of WCRs. A pattern of higher survival was observed in WCRs formed in Zone 2 (70°–65° W) or Zone 3 (65°–60° W) and then demised in Zone 1 (75°–70° W). Survival probability of the WCRs increased to more than 70% for those formed within a latitude band from 39.5° to 41.5° N. Survival probability is reduced when the WCRs are formed near the New England Seamounts.
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ArticleShelf break exchange processes influence the availability of the northern shortfin squid, Illex illecebrosus, in the Northwest Atlantic(Wiley, 2023-04-14) Salois, Sarah L. ; Hyde, Kimberly J. W. ; Silver, Adrienne ; Lowman, Brooke A. ; Gangopadhyay, Avijit ; Gawarkiewicz, Glen ; Mercer, Anna J. M. ; Manderson, John P. ; Gaichas, Sarah K. ; Hocking, Daniel J. ; Galuardi, Benjamin ; Jones, Andrew W. ; Kaelin, Jeff ; DiDomenico, Greg ; Almeida, Katie ; Bright, Bill ; Lapp, MeghanThe United States Northern Shortfin squid fishery is known for its large fluctuations in catch at annual scales. In the last 5 years, this fishery has experienced increased availability of Illex illecebrosus along the Northeast US continental shelf (NES), resulting in high catch per unit effort (CPUE) and early fishery closures due to quota exceedance. The fishery occurs within the Northwest Atlantic, whose complex dynamics are set up by the interplay between the large‐scale Gulf Stream, mesoscale eddies, Shelfbreak Jet, and shelf‐slope exchange processes. Our ability to understand and quantify this regional variability is requisite for understanding the availability patterns of Illex, which are largely influenced by oceanographic conditions. In an effort to advance our current understanding of the seasonal and interannual variability in this species' relative abundance on the NES, we used generalized additive models to examine the relationships between the physical environment and hotspots of productivity to changes in CPUE of I. illecebrosus in the Southern stock component, which comprises the US fishery. Specifically, we derived oceanographic indicators by pairing high‐resolution remote sensing data and global ocean reanalysis physical data to high‐resolution fishery catch data. We identified a suite of environmental covariates that were strongly related to instances of higher catch rates. In particular, bottom temperature, warm core rings, subsurface features, and frontal dynamics together serve as indicators of habitat condition and primary productivity hotspots, providing great utility for understanding the distribution of Illex with the potential for forecasting seasonal and interannual availability.