JpGU-AGU Joint Meeting 2017

Presentation information

[JJ] Oral

A (Atmospheric and Hydrospheric Sciences) » A-OS Ocean Sciences & Ocean Environment

[A-OS22] [JJ] Physical Oceanography

Mon. May 22, 2017 9:00 AM - 10:30 AM 302 (International Conference Hall 3F)

convener:Tomoki Tozuka(Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo), Yutaka Yoshikawa(Graduate School of Science, Kyoto University), Shinya Kouketsu(JAMSTEC Japan Agency for Marine-Earth Science and Technology), Yuki Tanaka(Graduate School of Science, The University of Tokyo), Chairperson:Tomoki Tozuka(Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo), Chairperson:Shinya Kouketsu(JAMSTEC)

9:00 AM - 9:15 AM

[AOS22-01] The Impact of Ocean Surface Currents on Global Eddy Kinetic Energy via the Wind Stress Formulation

*Zhitao Yu1, Edward Joe Metzger1 (1.US NRL)

Keywords:HYCOM, eddy kinetic energy, wind work, baroclinic instability, wind stress

A more complete wind stress formulation takes into account the ocean surface currents, while the conventional wind stress popularly used in ocean circulation models is only a function of 10-m winds. 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 study the impact of ocean surface currents on global Eddy Kinetic Energy (EKE). The model results (2004-2014) show that including ocean surface currents in surface wind stress formulation reduces global EKE by more than 40%. To understand the mechanisms behind the large difference, we calculate the global EKE budget using the standard Reynolds averaging procedure. The direct impact of surface wind stress on EKE is through surface wind work. The indirect impact is through changes in the mean circulation that affect the shear production, buoyancy work, and bottom friction. Model Results indicate that the reduction of global EKE is primarily due to the buoyancy work and shear production. Even though the surface eddy wind work is one order larger than buoyancy work, and two orders larger than shear production, it is mainly balanced by bottom friction and thus not the main contribution for the EKE differences.