The Impact of Ocean Surface Currents on Global Eddy Kinetic Energy via the Wind Stress Formulation

A pair of 12.5-year (July 2002-December 2014) HYbrid Coordinate Ocean Model (HYCOM) simulations that only differ in the wind stress formulation are used to investigate the effect of ocean surface currents on global monthly Eddy Kinetic Energy (EKE) variation. The model results (2004-2014) show that the global monthly mean EKE is reduced by 37%, from 1.76 EJ ( J) to 1.10 EJ after ocean surface currents are included in the wind stress formulation. The monthly EKE budget indicates that the shear production and buoyancy work are positive (energy source) and the eddy wind work on the geostrophic currents is negative (energy sink) in the steady state (2004-2014) for both simulations. All of these three terms are reduced in the steady state when the ocean currents are included in the wind stress formulation. The global integral of the EKE difference budget suggests that the EKE reduction is primarily due to the reduction of the buoyancy work, followed by the reduction of the wind work on the geostrophic currents and the shear production. To our knowledge this is the first study to separate the eddy wind work into the geostrophic and ageostrophic components to investigate the impact of ocean surface currents on global and depth integrated EKE via the wind stress formulation using HYCOM simulations.