A Gray-Radiation Aquaplanet Moist GCM. Part II: Energy Transports in Altered Climates

Frierson, Dargan M. W.; Held, Isaac M.; Zurita‐Gotor, Pablo

doi:10.1175/jas3913.1

Cited by 137 publications

(150 citation statements)

References 29 publications

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“…More recent studies (e.g., Flannery 1984;Frierson et al 2007;Hwang and Frierson 2010;Hwang et al 2011;Rose et al 2014;Roe et al 2015;Liu et al 2016;Merlis and Henry 2018;Siler et al 2018;Bonan et al 2018) account for latent heat by assuming that AHT is proportional to the meridional gradient in zonal-mean near-surface MSE, …”

Section: A Diffusive Perspectivementioning

confidence: 99%

Meridional atmospheric heat transport constrained by energetics and mediated by large-scale diffusion

Armour¹,

Siler²,

Donohoe³

et al. 2018

Preprint

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Meridional atmospheric heat transport (AHT) has been investigated through three broad perspectives: a dynamic perspective, linking AHT to the poleward flux of moist static energy (MSE) by atmospheric motions; an energetic perspective, linking AHT to energy input to the atmosphere by top-of-atmosphere radiation and surface heat fluxes; and a diffusive perspective, representing AHT in terms down-gradient energy transport. It is shown here that the three perspectives provide complementary diagnostics of meridional AHT and its changes under greenhouse-gas forcing. When combined, the energetic and diffusive perspectives offer prognostic insights: anomalous AHT is constrained to satisfy the net energetic demands of radiative forcing, radiative feedbacks, and ocean heat uptake; in turn, the meridional pattern of warming must adjust to produce those AHT changes, and does so approximately according to diffusion of anomalous MSE. The relationship between temperature and MSE exerts strong constraints on the warming pattern, favoring polar amplification. These conclusions are supported by use of a diffusive moist energy balance model (EBM) that accurately predicts zonal-mean warming and AHT changes within comprehensive general circulation models (GCMs). A dry diffusive EBM predicts similar AHT changes in order to satisfy the same energetic constraints, but does so through tropically-amplified warming -at odds with the GCMs' polar-amplified warming pattern. The results suggest that polar-amplified warming is a near-inevitable consequence of a moist, diffusive atmosphere's response to greenhouse-gas forcing. In this view, atmospheric circulations must act to satisfy net AHT as constrained by energetics.

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Section: A Diffusive Perspectivementioning

confidence: 99%

Meridional atmospheric heat transport constrained by energetics and mediated by large-scale diffusion

Armour¹,

Siler²,

Donohoe³

et al. 2018

Preprint

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“…27, κ M is an eddy diffusivity coefficient, often utilized for parameterization of unresolved turbulence in climate science (40,41), whereas _ W ðx;tÞ denotes space-time white noise forcing with variance parameter σ T . In the rapid decorrelation limit of Eq.…”

Section: Improving Response In a Complex Test Modelmentioning

confidence: 99%

Link between statistical equilibrium fidelity and forecasting skill for complex systems with model error

Majda

Gershgorin

2011

Proc. Natl. Acad. Sci. U.S.A.

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Understanding and improving the predictive skill of imperfect models for complex systems in their response to external forcing is a crucial issue in diverse applications such as for example climate change science. Equilibrium statistical fidelity of the imperfect model on suitable coarse-grained variables is a necessary but not sufficient condition for this predictive skill, and elementary examples are given here demonstrating this. Here, with equilibrium statistical fidelity of the imperfect model, a direct link is developed between the predictive fidelity of specific test problems in the training phase where the perfect natural system is observed and the predictive skill for the forced response of the imperfect model by combining appropriate concepts from information theory with other concepts based on the fluctuation dissipation theorem. Here a suite of mathematically tractable models with nontrivial eddy diffusivity, variance, and intermittent non-Gaussian statistics mimicking crucial features of atmospheric tracers together with stochastically forced standard eddy diffusivity approximation with model error are utilized to illustrate this link.P redicting the long-range behavior of complex systems in nature in diverse disciplines ranging from climate change science (1, 2) to materials (3) and neuroscience (4) is an issue of central importance in contemporary engineering and science. Accurate predictions are hampered by the fact that the true dynamics of the system in nature are actually unknown due to inadequate scientific understanding or inadequate spatiotemporal resolution in the imperfect computer models used for these predictions; in other words, there are significant model errors compared to the true signal from nature. Recently, information theory has been utilized in different ways to systematically improve model fidelity and sensitivity (5, 6), to quantify the role of coarse-grained initial states in long-range forecasting (7,8), and to make an empirical link between model fidelity and forecasting skill (9, 10). Imperfect models for complex systems are constrained by their capability to reproduce certain statistics in a training phase where the natural system has been observed; for example, this training phase in climate science is roughly the 60-y dataset of extensive observations of the Earth's climate system. For long-range forecasting, it is natural to guarantee statistical equilibrium fidelity for an imperfect model, and a framework using information theory is a natural way to achieve this in an unbiased fashion (5-8, 10). First, equilibrium statistical fidelity for an imperfect model depends on the choice of coarse-grained variables utilized (5, 6); second, equilibrium model fidelity is a necessary but not sufficient condition to guarantee long-range forecasting skill (8). For example, ref. 11, Sect. 2.6, extensively discusses three very different strongly mixing chaotic dynamical models with 40 variables and with the same Gaussian equilibrium measure, the TBH, K-Z, and IL96 models, so that al...

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“…Stone's result is often interpreted as being a consequence of the atmosphere being close to a state in which the outgoing longwave radiation is uniform in latitude due to the efficient meridional energy transport by the atmosphere (see, for example, the discussion in Frierson et al 2007). However, in Stone's detailed calculations (his section 3), rather than assuming an absence of OLR gradients, he notes a serendipitous cancellation of the effects of the gradients in OLR with gradients in absorbed solar radiation associated with interhemispheric variations in albedo.…”

Section: Total Heat Transportmentioning

confidence: 99%

Explorations of Atmosphere–Ocean–Ice Climates on an Aquaplanet and Their Meridional Energy Transports

Enderton

Marshall

2009

Journal of the Atmospheric Sciences

100

123

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The degree to which total meridional heat transport is sensitive to the details of its atmospheric and oceanic components is explored. A coupled atmosphere, ocean, and sea ice model of an aquaplanet is employed to simulate very different climates-some with polar ice caps, some without-even though they are driven by the same incoming solar flux. Differences arise due to varying geometrical constraints on ocean circulation influencing its ability to transport heat meridionally. Without complex land configurations, the results prove easier to diagnose and compare to theory and simple models and, hence, provide a useful test bed for ideas about heat transport and its partition within the climate system. In particular, the results are discussed in the context of a 1978 study by Stone, who argued that for a planet with Earth's astronomical parameters and rotation rate, the total meridional heat transport would be independent of the detailed dynamical processes responsible for that transport and depend primarily on the distribution of incoming solar radiation and the mean planetary albedo. The authors find that in warm climates in which there is no ice, Stone's result is a useful guide. In cold climates with significant polar ice caps, however, meridional gradients in albedo significantly affect the absorption of solar radiation and need to be included in any detailed calculation or discussion of total heat transport. Since the meridional extent of polar ice caps is sensitive to details of atmospheric and oceanic circulation, these cannot be ignored. Finally, what has been learned is applied to a study of the total heat transport estimated from the Earth Radiation Budget Experiment (ERBE) data.

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A Gray-Radiation Aquaplanet Moist GCM. Part II: Energy Transports in Altered Climates

Cited by 137 publications

References 29 publications

Meridional atmospheric heat transport constrained by energetics and mediated by large-scale diffusion

Meridional atmospheric heat transport constrained by energetics and mediated by large-scale diffusion

Link between statistical equilibrium fidelity and forecasting skill for complex systems with model error

Explorations of Atmosphere–Ocean–Ice Climates on an Aquaplanet and Their Meridional Energy Transports

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