TY - JOUR
T1 - The impact of horizontal resolution on energy transfers in global ocean models
AU - Kjellsson, Joakim
AU - Zanna, Laure
N1 - Funding Information:
Acknowledgments: We sincerely thank Rei Chemke and two anonymous reviewers, whose comments improved the paper greatly. We thank Andrew Coward for performing the NEMO simulations and giving us access to the output. We thank Thomas Bolton and Tomos David for useful discussions and suggestions. All numerical calculations where performed on the Jasmin storage and computing centre provided by the Centre for Environmental Data Analysis (CEDA). Funding is by Natural Environment Research Council (NERC) grants No.NE/K013548/1 and grants No.NE/J00586X/1.
Publisher Copyright:
© 2016 by the authors; licensee MDPI, Basel, Switzerland.
PY - 2017/9
Y1 - 2017/9
N2 - The ocean is a turbulent fluid with processes acting on a variety of spatio-temporal scales. The estimates of energy fluxes between length scales allows us to understand how the mean flow is maintained as well as how mesoscale eddies are formed and dissipated. Here, we quantify the kinetic energy budget in a suite of realistic global ocean models, with varying horizontal resolution and horizontal viscosity. We show that eddy-permitting ocean models have weaker kinetic energy cascades than eddy-resolving models due to discrepancies in the effect of wind forcing, horizontal viscosity, potential to kinetic energy conversion, and nonlinear interactions on the kinetic energy (KE) budget. However, the change in eddy kinetic energy between the eddy-permitting and the eddy-resolving model is not enough to noticeably change the scale where the inverse cascade arrests or the Rhines scale. In addition, we show that the mechanism by which baroclinic flows organise into barotropic flows is weaker at lower resolution, resulting in a more baroclinic flow. Hence, the horizontal resolution impacts the vertical structure of the simulated flow. Our results suggest that the effect of mesoscale eddies can be parameterised by enhancing the potential to kinetic energy conversion, i.e., the horizontal pressure gradients, or enhancing the inverse cascade of kinetic energy.
AB - The ocean is a turbulent fluid with processes acting on a variety of spatio-temporal scales. The estimates of energy fluxes between length scales allows us to understand how the mean flow is maintained as well as how mesoscale eddies are formed and dissipated. Here, we quantify the kinetic energy budget in a suite of realistic global ocean models, with varying horizontal resolution and horizontal viscosity. We show that eddy-permitting ocean models have weaker kinetic energy cascades than eddy-resolving models due to discrepancies in the effect of wind forcing, horizontal viscosity, potential to kinetic energy conversion, and nonlinear interactions on the kinetic energy (KE) budget. However, the change in eddy kinetic energy between the eddy-permitting and the eddy-resolving model is not enough to noticeably change the scale where the inverse cascade arrests or the Rhines scale. In addition, we show that the mechanism by which baroclinic flows organise into barotropic flows is weaker at lower resolution, resulting in a more baroclinic flow. Hence, the horizontal resolution impacts the vertical structure of the simulated flow. Our results suggest that the effect of mesoscale eddies can be parameterised by enhancing the potential to kinetic energy conversion, i.e., the horizontal pressure gradients, or enhancing the inverse cascade of kinetic energy.
KW - Eddy parameterisation
KW - Horizontal resolution
KW - Kinetic energy
KW - Nucleus for european modelling of the ocean (NEMO)
KW - Ocean model
KW - Spectral flux
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U2 - 10.3390/fluids2030045
DO - 10.3390/fluids2030045
M3 - Article
AN - SCOPUS:85046434739
VL - 2
JO - Fluids
JF - Fluids
SN - 2311-5521
IS - 3
M1 - 45
ER -