Decadal Variability of Eddy Kinetic Energy in the South Pacific Subtropical Countercurrent in an Ocean General Circulation Model

• DOI: 10.1175/jpo-d-17-0173.1
• Publication Date: 2018-02-08T18:17:58Z
• Authors: Jan K. Rieck; Claus W. Böning; Richard J. Greatb...
• Keywords: Wind Stress; Ekman transport; Downwelling

Abstract The eddy kinetic energy (EKE) associated with the Subtropical Countercurrent (STCC) in western subtropical South Pacific is known to exhibit substantial seasonal and decadal variability. Using an eddy-permitting ocean general circulation model, which able reproduce observed, salient features of cycles shear, stratification, baroclinic production, EKE, authors investigate changes EKE. show that STCC region exhibits, uniquely among gyres world’s oceans, significant, atmospherically forced, EKE variations are driven by changing vertical shear between upper 300 m Equatorial Current below, predominantly caused strength a meridional density gradient. In 1970s, increased gradient results twice as large later decades model. Utilizing sensitivity experiments, wind field shown be essential driver. Local stress curl anomalies interdecadal oscillation (IPO) lead upwelling downwelling thermocline, inducing strengthening or weakening Additionally, remote eastern Pacific, not related IPO, generate propagate westward Rossby waves can account for up 30%–40% investigated region.