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  • 1
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    Energy budget-based backscatter in a shallow water model of a double gyre basin (2018)
    Elsevier
    In:  Ocean Modelling, 132 . pp. 1-11.
    Details
    Publication Date: 2021-02-08
    Description: The parameterization of sub-grid scale processes is one of the key challenges towards improved numerical simulations of the atmospheric and oceanic circulation. Numerical weather prediction models as well as climate models would benefit from more sophisticated turbulence closures that allow for less spurious dissipation at the grid-scale and consequently higher and more realistic levels of eddy kinetic energy (EKE). Recent studies propose to use a hyperviscous closure in combination with an additional deterministic forcing term as a negative viscosity to represent backscatter of energy from unresolved scales. The sub-grid EKE is introduced as an additional prognostic variable that is fed by dissipation at the grid scale, and enables recycling of EKE via the backscatter term at larger scales. This parameterization was previously shown to work well in zonally re-entrant channel configurations. Here, a generalization in the form of a Rossby number-dependent scaling for the strength of the backscatter is introduced to represent the emergence of a forward energy-cascade in unbalanced flows near the boundaries. We apply the parameterization to a shallow water model of a double gyre basin and provide evidence for its general applicability. In terms of mean state and variability, a low resolution model is considerably improved towards a high resolution control run at low additional computational cost.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    DOI: 10.1016/j.ocemod.2018.09.006
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    Tropical Atmosphere-Ocean Interactions in a Conceptual Framework (2009)
    AMS (American Meteorological Society)
    In:  Journal of Climate, 22 . pp. 550-567.
    Details
    Publication Date: 2020-08-04
    Description: Statistical analysis of observations (including atmospheric reanalysis and forced ocean model simulations) is used to address two questions: First, does an analogous mechanism to that of El Niño–Southern Oscillation (ENSO) exist in the equatorial Atlantic or Indian Ocean? Second, does the intrinsic variability in these basins matter for ENSO predictability? These questions are addressed by assessing the existence and strength of the Bjerknes and delayed negative feedbacks in each tropical basin, and by fitting conceptual recharge oscillator models, both with and without interactions among the basins. In the equatorial Atlantic the Bjerknes and delayed negative feedbacks exist, although weaker than in the Pacific. Equatorial Atlantic variability is well described by the recharge oscillator model, with an oscillatory mixed ocean dynamics–sea surface temperature (SST) mode present in boreal spring and summer. The dynamics of the tropical Indian Ocean, however, appear to be quite different: no recharge–discharge mechanism is found. Although a positive Bjerknes-like feedback from July to September is found, the role of heat content seems secondary. Results also show that Indian Ocean interaction with ENSO tends to damp the ENSO oscillation and is responsible for a frequency shift to shorter periods. However, the retrospective forecast skill of the conceptual model is hardly improved by explicitly including Indian Ocean SST. The interaction between ENSO and the equatorial Atlantic variability is weaker. However, a feedback from the Atlantic on ENSO appears to exist, which slightly improves the retrospective forecast skill of the conceptual model.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1175/2008JCLI2243.1
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    NeverWorld2: an idealized model hierarchy to investigate ocean mesoscale eddies across resolutions (2023)
    European Geosciences Union
    Details
    Publication Date: 2023-03-08
    Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Marques, G. M., Loose, N., Yankovsky, E., Steinberg, J. M., Chang, C.-Y., Bhamidipati, N., Adcroft, A., Fox-Kemper, B., Griffies, S. M., Hallberg, R. W., Jansen, M. F., Khatri, H., & Zanna, L. NeverWorld2: an idealized model hierarchy to investigate ocean mesoscale eddies across resolutions. Geoscientific Model Development, 15(17), (2022): 6567–6579, https://doi.org/10.5194/gmd-15-6567-2022.
    Description: We describe an idealized primitive-equation model for studying mesoscale turbulence and leverage a hierarchy of grid resolutions to make eddy-resolving calculations on the finest grids more affordable. The model has intermediate complexity, incorporating basin-scale geometry with idealized Atlantic and Southern oceans and with non-uniform ocean depth to allow for mesoscale eddy interactions with topography. The model is perfectly adiabatic and spans the Equator and thus fills a gap between quasi-geostrophic models, which cannot span two hemispheres, and idealized general circulation models, which generally include diabatic processes and buoyancy forcing. We show that the model solution is approaching convergence in mean kinetic energy for the ocean mesoscale processes of interest and has a rich range of dynamics with circulation features that emerge only due to resolving mesoscale turbulence.
    Description: This research has been supported by the US Department of Commerce (grant no. NA18OAR4320123), the Division of Ocean Sciences (grant nos. 1912420, 1912332, 1912357, 1912163, and 1912302), the Division of Atmospheric and Geospace Sciences (grant no. 1852977), and the Climate Program Office (grant nos. NA19OAR4310364, NA19OAR4310365, and NA19OAR4310366).
    Repository Name: Woods Hole Open Access Server
    Type: Article
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    PAPER (OA)
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