ENSO Effects on Gulf of Alaska Eddies

Melsom, Arne; Meyers, Steven D.; Hurlburt, Harley E.; Metzger, E. Joseph; O’Brien, James J.

doi:10.1175/1087-3562(1999)003<0001:eeogoa>2.0.co;2

Cited by 27 publications

(45 citation statements)

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“…We see that the e-folding time is about 10-20 days in which there are large positive transfer rates. This e-folding time is consistent with what other investigators have found for eddies like those produced here (e.g., Melsom et al 1999). When e-folding times are calculated using only the EKE and the barotropic transfer rate, or only the EPE and the baroclinic transfer rate, values of 10-20 days are again obtained.…”

Section: B Baroclinic and Barotropic Energy Transferssupporting

confidence: 91%

“…Volume integrals of energy transfer rates along the east coast of the Gulf (from 50°to 60°N and 216°to 230°W) were computed, and the ratio of the volume integrals of positive barotropic to positive baroclinic transfer rates was 1.2, while the ratio of total barotropic to baroclinic transfer rates was 0.9 in the same area. This result is consistent with that of Melsom et al (1999), who used an eigenvalue/ eigenvector technique to infer that it was a combined barotropic/baroclinic instability process that produced anticyclonic eddies in the region. Taking 5 ϫ 10 Ϫ3 J m Ϫ2 s Ϫ1 as a typical large positive value for the baroclinic and barotropic fluxes along the east coast of the Gulf, then for circular eddies of 200 km diameter, one obtains an energy transfer rate on the order of 1.6 ϫ 10 8 J s Ϫ1 for typical eddies in this region.…”

Section: B Baroclinic and Barotropic Energy Transferssupporting

confidence: 88%

“…1), which suggests that the strait is baroclinically unstable. Melsom et al (1999) present model results that suggest that both barotropic and baroclinic instabilities contribute to eddy development along the east coast of the Gulf of Alaska. Swaters and Mysak (1985) presented an analysis of the Sitka eddy, located off the shelf, seaward of Sitka, Alaska ( Fig.…”

Section: Introductionmentioning

confidence: 91%

“…Numerical modeling investigations of the circulation in the Gulf of Alaska include studies of the dependence of eddy formation and strength on ENSO events, interannual variability, topography, and winds (e.g., Melsom et al 1999;Okkonen et al 2001;Cummins et al 2001;Murray et al 2001;Masson 2002;Hermann et al 2002;Di Lorenzo et al 2005). Recently, Stacey et al (2006) used the Parallel Ocean Program (POP) (Maltrud et al 1998;Smith et al 2000) to simulate the circulation in the North Pacific Ocean, with emphasis on the Gulf of Alaska.…”

Section: Introductionmentioning

confidence: 99%

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Sources of Eddy Energy Simulated by a Model of the Northeast Pacific Ocean

Shore

Stacey

Wright

2008

Journal of Physical Oceanography

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This paper examines the energy sources for eddy variability in the Gulf of Alaska using a numerical model and a novel form of data assimilation referred to as spectral nudging. Spectral nudging is distinguished from conventional nudging by its ability to operate only on specified frequency and wavenumber bands; in the present case, only the subannual variability is nudged, and only on spatial scales of 100 km or more. By using this approach, the broad-brush aspects of the model's mean state are constrained to remain near the mean climatological conditions, while the simulated eddy field is determined by the model dynamics. Simulations of the North Pacific Ocean with a 0.25°horizontal resolution and spectral nudging have been previously shown to produce eddy fields that are significantly more energetic and more realistic than those produced by prognostic (i.e., not nudged) simulations. The analysis of the spectrally nudged model results undertaken here reveals the tendency of the circulation to be both baroclinically and barotropically unstable in different regions and to differing degrees. Along the north coast of the Gulf of Alaska, the simulation suggests that barotropic instability is more important overall as an energy source for eddies than is baroclinic instability. Along the east coast of the Gulf of Alaska, the simulation suggests that both baroclinic and barotropic instabilities are important. Although the overall energy transfer is from the mean state to the eddy field, there are regions of the model, particularly along the north coast of the Gulf of Alaska, where the transfer of energy is from the eddy field to the mean flow.

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Section: B Baroclinic and Barotropic Energy Transferssupporting

confidence: 91%

Section: B Baroclinic and Barotropic Energy Transferssupporting

confidence: 88%

Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

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Sources of Eddy Energy Simulated by a Model of the Northeast Pacific Ocean

Shore

Stacey

Wright

2008

Journal of Physical Oceanography

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“…Melsom et al [1999] also found eddies frequently formed at these two locations in their numerical simulations.The continental shelf is narrow in these places, leading to speculation that squeezing of coastal currents here may intensify the vertical shear and baroclinic instability that sets up the eddies.…”

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confidence: 79%

Mesoscale eddy aswirl with data in Gulf of Alaska

Crawford

Whitney²

1999

EoS Transactions

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For the first time ever in the Gulf of Alaska, an anticyclonic mesoscale eddy's formation, migration, and transport have been observed and thoroughly documented. The eddy, Haida‐1998, was found to be one of an annual supply of eddies that transport fresh water and nutrients into the mid‐gulf from the Alaskan panhandle and the Canadian west coast. Haida‐1998's core had an unusually high elevation, making it one of the largest eddies ever observed in this region. Its strength is attributed to oceanic features associated with the 1997–1998 El Niño winter. The eddy was still active in early July 1999 and is expected to remain intact into the year 2000. By that time it will be one of the last surviving features of the 1997–1998 El Niño in the northeast Pacific Ocean.

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Anomalous eddy heat and freshwater transport in the Gulf of Alaska

Lyman

Johnson

2015

JGR Oceans

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Characteristics of eddies in the Gulf of Alaska are assessed from January 2003 through April 2012. Ensemble statistics for eddy subsurface water properties on isopycnals are computed using temperature and salinity profiles from Argo profiling floats located within eddies, which are identified in sea-surface height using objective techniques. Ninety cyclonic and 154 anticyclonic eddies are identified during this period. The anticyclonic eddies are strongly nonlinear and exhibit significant warm subsurface temperature anomalies and associated salty anomalies on isopycnals while no clear distinguishing subsurface anomalies on isopycnals are detected in association with the cyclonic eddies. Heat and freshwater fluxes for the eddies are estimated from integrations in depth coordinates. The anticyclonic eddies transport heat both westward off the continental shelf into the Subarctic Gyre and westward within the Alaskan Stream. However, they transport salt into the Subarctic Gyre and freshwater within the Alaskan Stream. In both pathways eddy heat and freshwater transport show possible year-to-year fluctuations, varying from 0 to 50.4 3 10 18 J a 21 and 216.8 to 17.4 km 3 a 21 , respectively. The anticyclonic eddies are capped by relatively fresh water yearround.

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ENSO Effects on Gulf of Alaska Eddies

Cited by 27 publications

References 0 publications

Sources of Eddy Energy Simulated by a Model of the Northeast Pacific Ocean

Sources of Eddy Energy Simulated by a Model of the Northeast Pacific Ocean

Mesoscale eddy aswirl with data in Gulf of Alaska

Anomalous eddy heat and freshwater transport in the Gulf of Alaska

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