From Internal Gravity Waves to the Mesoscale: Potential and Kinetic Energy Frequency Spectra in Global Ocean Models versus Data.
Conrad A Luecke1, Brian K Arbic1, Joseph K Ansong1, Steven Bassette1, Maarten C Buijsman2, Dimitris Menemenlis3, Jim G. Richman4, Jay F Shriver5, Patrick G Timko6, Alan J Wallcraft7 and Luis Zamudio8, (1)University of Michigan Ann Arbor, Ann Arbor, MI, United States, (2)University of Southern Mississippi, Stennis Space Center, MS, United States, (3)Jet Propulsion Laboratory, Pasadena, CA, United States, (4)Center for Ocean-Atmospheric Prediction Studies, Florida State University, Tallahassee, FL, United States, (5)US Naval Research Laboratory, Stennis Space Center, MS, United States, (6)University of Michigan, Dept of Earth and Environmental Sciences, Ann Arbor, MI, United States, (7)Naval Research Laboratory, Stennis Space Center, MS, United States, (8)Florida State University, Tallahassee, FL, United States
Abstract:
Global ocean models with spatial grids on the order of a few kilometers are on the cusp of resolving small-scale, higher-frequency motions, such as tidally generated and supertidal internal gravity waves. The question arises as to how the spatial resolution of these models changes the dynamics and energetics of motions ranging from the mesoscale to the supertidal.
We compare modeled kinetic and available potential energy frequency spectra with a global archive of historical moored instruments across periods spanning hours to years, thus encompassing a wide range of dynamic oceanic processes. We use global simulations of both the MIT General Circulation Model (MITgcm), and the HYbrid Coordinate Ocean Model (HYCOM). Both models are run at varying horizontal resolutions (1/12, 1/24, and 1/48 degree for MITgcm, and 1/12, 1/25 degree for HYCOM). In addition, all of the model runs examined are forced by both atmospheric fields and the astronomic tidal potential, thus ensuring that energy is injected across the oceanic frequency spectrum.
Examination of the impact of changing spatial resolutions on global ocean energetics helps to validate the use of high resolution general circulation models in the study of mesoscale and internal wave energy reservoirs.
