Patterns of flow in the canyons of the northern Gulf of Alaska

Mordy, Calvin W.; Stabeno, Phyllis J.; Kachel, Nancy B.; Kachel, David; Ladd, Carol; Zimmermann, Mark; Hermann, Albert J.; Coyle, Kenneth O.; Doyle, Miriam J.

doi:10.1016/j.dsr2.2019.03.009

Cited by 19 publications

(14 citation statements)

References 46 publications

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“…To meet this need, we have been publishing 100 m resolution bathymetry compilations in recent years: AI [3], Cook Inlet (50 m resolution: [16]), Norton Sound [17], and central Gulf of Alaska (GOA, AK, USA) [18]. These bathymetry compilations have been utilized for a variety of fishery research purposes including fish vertical migration [19]; coral and sponge distribution modeling in the AI [20] and GOA [21]; quantifying inshore study sites in the central GOA [22], eastern GOA [23], and bathymetry groundtruthing [24]; bathymetric steering of seafloor current flow [25]; inshore habitat loss [26]; Essential Fish Habitat modeling in the EBS [27], GOA [28,29], and AI [30]; juvenile groundfish habitat suitability models [31]; and capelin (Mallotus villosus) distribution modeling [32].…”

Section: Bathymetry Compilations Oceanographic and Biological Researchmentioning

confidence: 99%

Bathymetry and Canyons of the Eastern Bering Sea Slope

Zimmermann

Prescott

2018

Geosciences

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We created a new, 100 m horizontal resolution bathymetry raster and used it to define 29 canyons of the eastern Bering Sea (EBS) slope area off of Alaska, USA. To create this bathymetry surface we proofed, edited, and digitized 18 million soundings from over 200 individual sources. Despite the vast size (~1250 km long by~3000 m high) and ecological significance of the EBS slope, there have been few hydrographic-quality charting cruises conducted in this area, so we relied mostly on uncalibrated underway files from cruises of convenience. The lack of hydrographic quality surveys, anecdotal reports of features such as pinnacles, and reliance on satellite altimetry data has created confusion in previous bathymetric compilations about the details along the slope, such as the shape and location of canyons along the edge of the slope, and hills and valleys on the adjacent shelf area. A better model of the EBS slope will be useful for geologists, oceanographers, and biologists studying the seafloor geomorphology and the unusually high productivity along this poorly understood seafloor feature.

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Section: Bathymetry Compilations Oceanographic and Biological Researchmentioning

confidence: 99%

Bathymetry and Canyons of the Eastern Bering Sea Slope

Zimmermann

Prescott

2018

Geosciences

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“…The Alaska Current morphs farther downstream near Kodiak Island into the Alaskan Stream, a narrow ∼50‐km intense western boundary current (Reed, ; Reed & Stabeno, , ; Stabeno & Hristova, ). The continental shelf of the Gulf of Alaska (GOA) sustains a rich ecosystem despite downwelling favorable winds, promoted in part by various cross‐shelf exchange mechanisms such as advection by eddies, flow in canyons, and downwelling relaxation due to episodic wind events (Ladd, Stabeno, et al, , ; Mordy et al, ; Stabeno et al, ) that result in the exchange of iron and micronutrients between the shelf and the basin and affect larval transport.…”

Section: Introductionmentioning

confidence: 99%

Variability and Trends of the Alaska Gyre From Argo and Satellite Altimetry

2019

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The interannual variability and trends of the Alaska Gyre and Gulf of Alaska (GOA) circulation are examined using meridional geostrophic transport from Argo temperature and salinity (2004–2017) and altimetric sea surface height (1993–2017). More than half of the top 1,500 m meridional transport variability in the Alaska Gyre is accounted for by a statistical mode strongly correlated with the Pacific Decadal Oscillation (PDO) index, consistent with the PDO exerting a major influence on North Pacific sea surface temperature variability. During a positive phase of the PDO, the zero‐transport streamline separating the subtropical from the Alaska Gyre is shifted to the south from its mean position, while more transport is diverted northward, associated with a stronger and larger Alaska Gyre. Additionally, over the 25‐year altimetric record there is a linear, increasing trend in strength of the Alaska Gyre (but not in areal extent), accompanied by an increasing trend for the incoming North Pacific Current. The effect of the PDO transport mode on GOA circulation is weak. Temperature and salinity volume averaged for the GOA covary with the PDO index, with warmer and fresher waters during a positive phase. Despite correlated anomalies for temperature, salinity, and northward transport into the GOA, however, geostrophic advection from the south contributes only minimally to the interannual variations of water properties in the GOA. An exception was the marine heat wave of 2013/2014 and its aftermath when temperature advection from the south played a more appreciable role for warming and subsequent cooling of the GOA.

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“…The near‐bottom flow field exhibits much weaker mean flow than at the surface and with shorter length scales, but the effect of seafloor topographic steering is still clear. Such pathways represent conduits for nutrient‐rich waters and plankton to leave the basin and advect onto the midshelf and inner‐shelf domains (Hermann et al, 2009; Mordy et al, 2019). The model depicts surface flow into Prince William Sound through Hinchinbrook Entrance and out of the Sound through Montague Strait, along with bidirectional subsurface flows in both straits (Halverson et al, 2013; Niebauer et al, 1994).…”

Section: Resultsmentioning

confidence: 99%

Demonstrating a High‐Resolution Gulf of Alaska Ocean Circulation Model Forced Across the Coastal Interface by High‐Resolution Terrestrial Hydrological Models

et al. 2020

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We demonstrate a linking of moderately high resolution (1 km) terrestrial hydrological models to a 3‐D ocean circulation model having similar resolution in the northern Gulf of Alaska, where a distributed line source of freshwater runoff exerts strong influence over the shelf's hydrographic structure and flow dynamics. The model interfacing is accomplished via mass flux boundary conditions through the ocean model coastal wall at all land‐ocean adjoining grid cells. Despite the high runoff volume and lack of a coastal mixing estuary, the implementation maintains numerical stability by prescribing depth invariant and surface‐intensified inflows at fast and slow discharge grid cells, respectively. Based on comparisons against in situ hydrographic data, the coastal sidewall mass flux boundary condition results in more realistic hindcast surface salinity and salinity gradient fields than models that distribute coastal runoff in the form of spatially distributed precipitation. Correlations with observed thermal and haline monthly anomalies reveal statistically significant hindcast temporal variability during the freshet season when the signal‐to‐noise ratio is large. Comparisons of ocean models forced by high‐ and low‐resolution hydrological models reveal differences in salinity, surface elevation, and velocity fields, highlighting the value and importance of accurate coastal runoff fields. The model results improve our understanding of the regional influence of runoff on sea level elevations and the distribution and fate of fresh water. Our approach has potential applications to biogeochemical modeling in regions where distributed line source freshwater coastal discharges deliver heat, momentum, and chemical constituents that may influence the marine carbon pump.

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Patterns of flow in the canyons of the northern Gulf of Alaska

Cited by 19 publications

References 46 publications

Bathymetry and Canyons of the Eastern Bering Sea Slope

Bathymetry and Canyons of the Eastern Bering Sea Slope

Variability and Trends of the Alaska Gyre From Argo and Satellite Altimetry

Demonstrating a High‐Resolution Gulf of Alaska Ocean Circulation Model Forced Across the Coastal Interface by High‐Resolution Terrestrial Hydrological Models

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