Global Estimates of the Energy Transfer From the Wind to the Ocean, With Emphasis on Near‐Inertial Oscillations. Issue 8 (15th August 2019)

• Record Type: Journal Article
• Authors: Flexas, M. Mar; Thompson, Andrew F.; Torres, Hector S.; Klein, Patrice; Farrar, J. Thomas; Zhang, Hong; Menemenlis, Dimitris
• Is Part Of: Journal of geophysical research. Volume 124:Issue 8(2019)
• Page Start: 5723
• Page End: 5746
• Publication Date: 2019-08-15
• Subjects: surface fluxes -- inertial oscillations -- wind power -- kinetic energy budget -- global ocean model -- MITgcm; Oceanography -- Periodicals; 551.4605
• DOI: 10.1029/2018JC014453
• Languages: English
• ISSNs: 2169-9275

Abstract

Abstract: Estimates of the kinetic energy transfer from the wind to the ocean are often limited by the spatial and temporal resolution of surface currents and surface winds. Here we examine the wind work in a pair of global, very high‐resolution (1/48° and 1/24°) MIT general circulation model simulations in Latitude‐Longitude‐polar Cap (LLC) configuration that provide hourly output at spatial resolutions of a few kilometers and include tidal forcing. A cospectrum analysis of wind stress and ocean surface currents shows positive contribution at large scales (>300 km) and near‐inertial frequency and negative contribution from mesoscales, tidal frequencies, and internal gravity waves. Larger surface kinetic energy fluxes are in the Kuroshio in winter at large scales (40 mW/m 2 ) and mesoscales (−30 mW/m 2 ). The Kerguelen region is dominated by large scale (∼20 mW/m 2 ), followed by inertial oscillations in summer (13 mW/m 2 ) and mesoscale in winter (−12 mW/m 2 ). Kinetic energy fluxes from internal gravity waves (−0.1 to −9.9 mW/m 2 ) are generally stronger in summer. Surface kinetic energy fluxes in the LLC simulations are 4.71 TW, which is 25–85% higher than previous global estimates from coarser (1/6–1/10°) general ocean circulation models; this is likely due to improved representation of wind variability (6‐hourly, 0.14°, operational European Center for Medium‐Range Weather Forecasts). However, the low wind power input to the near‐inertial frequency band obtained with LLC (0.16 TW) compared to global slab models suggests that wind variability on time scales less than 6 hr and spatial scales less than 15 km are critical to better representing the wind power input in ocean circulation models. Key Points: Surface kinetic energy fluxes from LLC simulations lead to 4.71 TW, this is 25–85% higher than previous global estimates There is positive contribution to wind power input (WPI) at large scale and near‐inertial (NI) band, and negative WPI at mesoscale, tidal frequencies and IGWs Low WPI at NI band (0.16 TW) suggests that wind variability on scales <6 hr and <15 km are critical to better representing WPI in GCMs