Interdecadal changes in mesoscale eddy variance in the Gulf of Alaska circulation: Implications for the Steller sea lion decline. Atmosphere-Ocean

• Main Authors: Arthur J. Miller, Emanuele Di Lorenzo, Douglas J. Neilson, Hey-jin Kim, Antonietta Capotondi, Michael A. Alex, Steven J. Bograd, Kate Hedstrom, David L. Musgrave
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2005
• Subjects: Gulf of Alaska; Tourbillons; aleutian low; Dépression des Aléoutiennes; Alaska
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.527.3968; http://eros.eas.gatech.edu/manu/papers/PDFs/Miller_GOA_Eddies_AO_2005.pdf

ABSTRACT A distinct change in the ocean circulation of the Gulf of Alaska after the 1976–77 climate shift is stud-ied in an eddy-permitting primitive equation model forced by observed wind stresses from 1951–99. When the Aleutian Low strengthens after 1976–77, strong changes occur in the mean velocity of the Alaskan Stream and in its associated mesoscale eddy field. In contrast, the Alaska Current and the eddy flows in the eastern Gulf remain relatively unchanged after the shift. Since mesoscale eddies provide a possible mechanism for transporting nutri-ent-rich open-ocean waters to the productive shelf region, the flow of energy through the food web may have been altered by this physical oceanographic change. This climate-driven mechanism, which has a characteristic east-west spatial asymmetry, may potentially help to explain changes in forage fish quality in diet diversity of Steller sea lions whose populations have declined precipitously since the mid-1970s in the western Gulf while remaining stable in the eastern Gulf. RESUMÉ [Traduit par la rédaction] On étudie un changement sensible dans la circulation océanique dans le golfe d’Alaska survenu après le changement climatique de 1976–1977 à l’aide d’un modèle à équations primitives permettant les tourbillons, entraîné par les tensions du vent observées entre 1951 et 1999. Quand la dépression des Aléoutiennes se renforce après 1976–1977, d’importants changements se produisent dans la vitesse moyenne du courant d’Alaska et dans son champ de tourbillon de mésoéchelle. Par contre, le courant d’Alaska et les tourbillons