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Journal ArticleDOI

Using a resolution function to regulate parameterizations of oceanic mesoscale eddy effects

01 Dec 2013-Ocean Modelling (Elsevier)-Vol. 72, pp 92-103
TL;DR: In this article, the first baroclinic deformation radius to the horizontal grid spacing indicates where an ocean model could explicitly simulate eddy effects; a function of this ratio can be used to specify where eddy effect are parameterized and where they are explicitly modeled.
About: This article is published in Ocean Modelling.The article was published on 2013-12-01. It has received 302 citations till now. The article focuses on the topics: Eddy diffusion & Eddy.
Citations
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Journal ArticleDOI
TL;DR: In this paper, a suite of centennial-scale 1990 radiatively forced numerical climate simulations from three GFDL coupled models comprising the Climate Model, version 2.0-Ocean (CM2-O), model suite is used to characterize impacts on heat in the ocean climate system from transient ocean mesoscale eddies.
Abstract: The authors characterize impacts on heat in the ocean climate system from transient ocean mesoscale eddies. Their tool is a suite of centennial-scale 1990 radiatively forced numerical climate simulations from three GFDL coupled models comprising the Climate Model, version 2.0–Ocean (CM2-O), model suite. CM2-O models differ in their ocean resolution: CM2.6 uses a 0.1° ocean grid, CM2.5 uses an intermediate grid with 0.25° spacing, and CM2-1deg uses a nominal 1.0° grid.Analysis of the ocean heat budget reveals that mesoscale eddies act to transport heat upward in a manner that partially compensates (or offsets) for the downward heat transport from the time-mean currents. Stronger vertical eddy heat transport in CM2.6 relative to CM2.5 accounts for the significantly smaller temperature drift in CM2.6. The mesoscale eddy parameterization used in CM2-1deg also imparts an upward heat transport, yet it differs systematically from that found in CM2.6. This analysis points to the fundamental role that ocea...

249 citations

Journal ArticleDOI
TL;DR: Guo et al. as mentioned in this paper describe the Geophysical Fluid Dynamics Laboratory's CM4.0 physical climate model, with emphasis on those aspects that may be of particular importance to users of this model and its simulations.
Abstract: We describe the Geophysical Fluid Dynamics Laboratory's CM4.0 physical climate model, with emphasis on those aspects that may be of particular importance to users of this model and its simulations. The model is built with the AM4.0/LM4.0 atmosphere/land model and OM4.0 ocean model. Topics include the rationale for key choices made in the model formulation, the stability as well as drift of the preindustrial control simulation, and comparison of key aspects of the historical simulations with observations from recent decades. Notable achievements include the relatively small biases in seasonal spatial patterns of top-of-atmosphere fluxes, surface temperature, and precipitation; reduced double Intertropical Convergence Zone bias; dramatically improved representation of ocean boundary currents; a high-quality simulation of climatological Arctic sea ice extent and its recent decline; and excellent simulation of the El Niño-Southern Oscillation spectrum and structure. Areas of concern include inadequate deep convection in the Nordic Seas; an inaccurate Antarctic sea ice simulation; precipitation and wind composites still affected by the equatorial cold tongue bias; muted variability in the Atlantic Meridional Overturning Circulation; strong 100 year quasiperiodicity in Southern Ocean ventilation; and a lack of historical warming before 1990 and too rapid warming thereafter due to high climate sensitivity and strong aerosol forcing, in contrast to the observational record. Overall, CM4.0 scores very well in its fidelity against observations compared to the Coupled Model Intercomparison Project Phase 5 generation in terms of both mean state and modes of variability and should prove a valuable new addition for analysis across a broad array of applications. Plain Language Summary The Geophysical Fluid Dynamics Laboratory (GFDL) of the National Oceanic and Atmospheric Administration participates along with a number of model centers around the world in constructing state-of-the-art climate models for use in studies for climate change and prediction. GFDL's latest multipurpose atmosphere-ocean coupled climate model, CM4.0, is described here. It consists of GFDL's latest atmosphere and land models at about 100 km horizontal resolution and ocean and sea ice models at roughly 25 km horizontal resolution. A handful of standard experiments have been conducted with CM4.0 for participation in the Coupled Model Intercomparison Project Phase 6, an archive of climate model results utilized by the Intergovernmental Panel on Climate Change and the climate research community more generally. The model results have been extensively evaluated against observations. This paper makes the case that CM4.0 ranks high among state-of-the-art coupled climate models by many measures of bias in the simulated climatology and in its ability to capture modes of climate variability such as the El Niño-Southern Oscillation and Madden-Julian Oscillation. The paper also discusses some potential weaknesses, including unrealistically large internal variability in the Southern Ocean and insufficient warming before 1990 in the simulation of the twentieth century. RESEARCH ARTICLE 10.1029/2019MS001829 Special Section: Geophysical Fluid Dynamics Laboratory CMIP6 Models Key Points: • A team at GFDL has developed a new model of the physical climate system referred to as CM4.0 • Strengths of model include ENSO simulation and small biases in TOA fluxes, precipitation, Arctic sea ice extent, and sea surface temperature • Problematic aspects include large variability in Southern Ocean and historical simulation with little warming prior to 1990 Correspondence to: H. Guo, huan.guo@noaa.gov Citation: Held, I. M., Guo, H., Adcroft, A., Dunne, J. P., Horowitz, L. W., Krasting, J., et al. (2019). Structure and performance of GFDL's CM4.0 climate model. Journal of Advances in Modeling Earth Systems, 11. https:// h ttps://doi.org/10.1029/ 2019MS001829 Received 25 JUL 2019 Accepted 14 OCT 2019 Accepted article online 30 OCT 2019 ©2019. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

243 citations

Journal ArticleDOI
TL;DR: In this paper, a convolutional neural network (CNN) was trained on degraded data from a high-resolution quasi-geostrophic ocean model to predict turbulent processes and subsurface flow fields.
Abstract: Oceanographic observations are limited by sampling rates, while ocean models are limited by finite resolution and high viscosity and diffusion coefficients. Therefore, both data from observations and ocean models lack information at small and fast scales. Methods are needed to either extract information, extrapolate, or upscale existing oceanographic data sets, to account for or represent unresolved physical processes. Here we use machine learning to leverage observations and model data by predicting unresolved turbulent processes and subsurface flow fields. As a proof of concept, we train convolutional neural networks on degraded data from a high-resolution quasi-geostrophic ocean model. We demonstrate that convolutional neural networks successfully replicate the spatiotemporal variability of the subgrid eddy momentum forcing, are capable of generalizing to a range of dynamical behaviors, and can be forced to respect global momentum conservation. The training data of our convolutional neural networks can be subsampled to 10–20% of the original size without a significant decrease in accuracy. We also show that the subsurface flow field can be predicted using only information at the surface (e.g., using only satellite altimetry data). Our results indicate that data-driven approaches can be exploited to predict both subgrid and large-scale processes, while respecting physical principles, even when data are limited to a particular region or external forcing. Our in-depth study presents evidence for the successful design of ocean eddy parameterizations for implementation in coarse-resolution climate models.

236 citations

01 Feb 2016
TL;DR: In this paper, a suite of centennial-scale 1990 radiatively forced numerical climate simulations from three GFDL coupled models comprising the Climate Model, version 2.0-Ocean (CM2-O), model suite is used to characterize impacts on heat in the ocean climate system from transient ocean mesoscale eddies.
Abstract: The authors characterize impacts on heat in the ocean climate system from transient ocean mesoscale eddies. Their tool is a suite of centennial-scale 1990 radiatively forced numerical climate simulations from three GFDL coupled models comprising the Climate Model, version 2.0–Ocean (CM2-O), model suite. CM2-O models differ in their ocean resolution: CM2.6 uses a 0.1° ocean grid, CM2.5 uses an intermediate grid with 0.25° spacing, and CM2-1deg uses a nominal 1.0° grid.Analysis of the ocean heat budget reveals that mesoscale eddies act to transport heat upward in a manner that partially compensates (or offsets) for the downward heat transport from the time-mean currents. Stronger vertical eddy heat transport in CM2.6 relative to CM2.5 accounts for the significantly smaller temperature drift in CM2.6. The mesoscale eddy parameterization used in CM2-1deg also imparts an upward heat transport, yet it differs systematically from that found in CM2.6. This analysis points to the fundamental role that ocea...

206 citations

Journal ArticleDOI
TL;DR: In this article, the authors present the Carbon Mitigation Initiative (CMI) project at Princeton University - BP and the National Oceanic and Atmospheric Administration, U.S. Department of Commerce.
Abstract: National Oceanic and Atmospheric Administration, U.S. Department of CommerceNational Oceanic Atmospheric Admin (NOAA) - USA [NA14OAR4320106]; Carbon Mitigation Initiative (CMI) project at Princeton University - BP; Natural Sciences and Engineering Research Council of Canada (NSERC)Natural Sciences and Engineering Research Council of Canada [RGPIN-2018-04985]; National Science FoundationNational Science Foundation (NSF) [1536350]

204 citations


Cites background or methods from "Using a resolution function to regu..."

  • ...The Laplacian viscosity is scaled to 529 zero wherever the first baroclinic deformation is resolved, namely in the tropics, using the 530 resolution function of [Hallberg, 2013]....

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  • ...The mesoscale eddy parameterization is not active in the tropical region (following Hallberg, 2013), so it is unknown if the eddy parameterization would reduce the differences found in the tropics....

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  • ...The extremely inhomogeneous nature of mesoscale eddy scales over the World Ocean requires even finer resolution before legitimately laying claim to numerical convergence at the mesoscale (see Figure 1 of Hallberg, 2013)....

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  • ...The Laplacian viscosity is scaled to zero wherever the first baroclinic deformation is resolved, namely in the tropics, using the resolution function of Hallberg (2013)....

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  • ...This horizontal grid permits mesoscale eddies over much of the tropical and subtropical oceans (see Figure 1 from Hallberg, 2013)....

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References
More filters
Book
14 Nov 2013
TL;DR: In this article, the authors describe how the Ocean-Atmosphere system is driven by transfer of properties between the atmosphere and the ocean. But they do not consider the effects of side boundaries.
Abstract: How the Ocean--Atmosphere System Is Driven. Transfer of Properties between Atmosphere and Ocean. Properties of a Fluid at Rest. Equations Satisfied by a Moving Fluid. Adjustment under Gravity in a Nonrotating System. Adjustment under Gravity of a Density-Stratified Fluid. Effect of Rotation. Gravity Waves in a Rotating Fluid. Forced Motion. Effects of Side Boundaries. The Tropics. Mid-Latitudes. Instabilities, Fronts, and the General Circulation. Units and Their SI Equivalents. Useful Values. Properties of Seawater. Properties of Moist Air. A List of Atlases and Data Sources. References. Index.

5,750 citations


"Using a resolution function to regu..." refers background in this paper

  • ...The dominant spatial scales of baroclinic ocean mesoscale eddies can be broadly characterized by the first baroclinic deformation radius, which is the distance that a nonrotating first-mode internal gravity wave would propagate in one inertial timescale (e.g. Gill, 1982)....

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  • ...…by cg ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi gDqh1h2 q0 h1 þ h2ð Þ s ; ð4Þ although in the general multilayered or continuously stratified case cg is given by the second largest eigenvalue of the normal mode decomposition equation (see chapter 6 of Gill, 1982)....

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Book
01 Jan 1979
TL;DR: In this article, the authors propose a quasigeostrophic motion of a Stratified Fluid on a Sphere (SFL) on a sphere, which is based on an Inviscid Shallow-Water Theory.
Abstract: Preliminaries * Fundamentals * Inviscid Shallow-Water Theory * Friction and Viscous Flow * Homogeneous Models of the Wind-Driven Oceanic Circulation * Quasigeostrophic Motion of a Stratified Fluid on a Sphere * Instability Theory * Ageostrophic Motion

5,558 citations


"Using a resolution function to regu..." refers background in this paper

  • ...In idealized models of baroclinic instability, the upper and lower bounds of unstable wavelengths are proportional to the deformation radius, while the most unstable wavenumber is the inverse of the deformation radius (see, e.g., the textbook by Pedlosky (1987))....

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  • ...…including necessary conditions for the growth of instabilities, the growth rate, energetics and vertical structure of the exponentially growing linear modes can be calculated analytically, as has been documented in many textbooks on geophysical fluid dynamics (e.g. Pedlosky, 1987; Vallis, 2006)....

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Journal ArticleDOI
TL;DR: In this paper, a subgrid-scale form for mesoscale eddy mixing on isopycnal surfaces is proposed for use in non-eddy-resolving ocean circulation models.
Abstract: A subgrid-scale form for mesoscale eddy mixing on isopycnal surfaces is proposed for use in non-eddy-resolving ocean circulation models. The mixing is applied in isopycnal coordinates to isopycnal layer thickness, or inverse density gradient, as well as to passive scalars, temperature and salinity. The transformation of these mixing forms to physical coordinates is also presented.

3,107 citations


"Using a resolution function to regu..." refers methods in this paper

  • ...…based on the extraction of available potential energy via the diffusion of isopycnal heights in layered models was the original inspiration for the Gent and McWilliams (1990) parameterization in z-coordinate models, and this parameterization is the equivalent in this two-layered system....

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MonographDOI
01 Nov 2006

1,443 citations

Journal ArticleDOI
TL;DR: In this paper, the first baroclinic gravity-wave phase speed c1 and the Rossby radius of deformation l1 are computed from climatological average temperature and salinity profiles.
Abstract: Global 1 83 18 climatologies of the first baroclinic gravity-wave phase speed c1 and the Rossby radius of deformation l1 are computed from climatological average temperature and salinity profiles. These new atlases are compared with previously published 5 83 58 coarse resolution maps of l1 for the Northern Hemisphere and the South Atlantic and with a 1 83 18 fine-resolution map of c1 for the tropical Pacific. It is concluded that the methods used in these earlier estimates yield values that are biased systematically low by 5%‐15% owing to seemingly minor computational errors. Geographical variations in the new high-resolution maps of c1 and l1 are discussed in terms of a WKB approximation that elucidates the effects of earth rotation, stratification, and water depth on these quantities. It is shown that the effects of temporal variations of the stratification can be neglected in the estimation of c1 and l1 at any particular location in the World Ocean. This is rationalized from consideration of the WKB approximation.

1,290 citations


"Using a resolution function to regu..." refers background in this paper

  • ...E-mail address: Robert.Hallberg@noaa.gov 1 This is just a simple function that goes smoothly between the appropriate equatorial and mid-latitude definitions of the deformation radius without the need for any arbitrary transition latitude (see, e.g. Chelton et al., 1998)....

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