Accueil > Actualités > Séminaires > Séminaire de Jan Klaus Rieck au LOCEAN


Titre : Decadal variations of Eddy Kinetic Energy in the South Pacific – Sensitivity Studies
Nom du conférencier : Jan Klaus Rieck
Son affiliation : GEOMAR
Laboratoire organisateur : LOCEAN
Date et heure : 28-03-2017 11h00
Lieu : Campus de Jussieu, salle de réunion LOCEAN, tour 45/55, 4eme étage
Résumé :

A series of eddying global ocean-sea ice models (NEMO3.6) is used to assess the low-frequency variability of Eddy Kinetic Energy in the world ocean. The models with horizontal resolutions ranging from 1/4°-1/12° are driven by the atmospheric CORE.v2 forcing for a period of 1958-2009. A region located between 25°-33°S and 153°-175°W stands out globally, having a high variance of EKE, relative to the mean EKE, at decadal timescales.

This region is characterized by the shallow, eastward South Tropical Countercurrent (STCC). The STCC, restricted to the upper 200m, forms a vertically sheared current system with the westward South Equatorial Current (SEC) below. While there are only minor changes to the SEC on decadal timescales, velocities of the STCC vary with a magnitude of >50% of the mean. The induced variations in vertical shear (du/dz) drive decadal EKE changes.

To investigate the sources for these decadal changes, various sensitivity simulations are performed with a 1/4° ocean model. These simulations reveal changes in wind stress τ to be the essential driver behind changes in the STCC. A possible link to the Pacific Decadal Oscillation (PDO) is explored.

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