Low-Frequency Variability in the Midlatitude Atmosphere Induced by an Oceanic Thermal Front

Feliks, Yizhak; Ghil, Michael; Simonnet, Eric

doi:10.1175/1520-0469(2004)061<0961:lvitma>2.0.co;2

Cited by 82 publications

(108 citation statements)

References 52 publications

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“…The sign, magnitude, and spatial pattern of this feedback inferred from GCM results is, however, controversial; compare, for example, Peng et al (1995Peng et al ( , 1997 and Kushnir and Held (1996). In general, the linear response of the atmospheric circulation to SST anomalies associated with mid-latitude variability is weak; see, however, Feliks et al (2004Feliks et al ( , 2007. Kravtsov et al (2006bKravtsov et al ( , 2007a, in their idealized quasi-geostrophic (QG) oceanatmosphere model, have recently identified a novel type of coupled behavior in which atmospheric nonlinearity plays a key role.…”

Section: Introductionmentioning

confidence: 99%

A mechanistic model of mid-latitude decadal climate variability

Kravtsov

Dewar

Ghil

et al. 2008

Physica D: Nonlinear Phenomena

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A simple heuristic model of coupled decadal ocean-atmosphere modes in middle latitudes is developed. Previous studies have treated atmospheric intrinsic variability as a linear stochastic process modified by a deterministic coupling to the ocean.The present paper takes an alternative view: based on observational, as well as process modeling results, it represents this variability in terms of irregular transitions between two anomalously persistent, high-latitude and low-latitude jet-stream states. Atmospheric behavior is thus governed by an equation analogous to that describing the trajectory of a particle in a double-well potential, subject to stochastic forcing. Oceanic adjustment to a positional shift in the atmospheric jet involves persistent circulation anomalies maintained by the action of baroclinic eddies; this process is parameterized in the model as a delayed oceanic response. The associated sea-surface temperature anomalies provide heat fluxes that affect atmospheric circulation by modifying the shape of the double-well potential. If the latter coupling is strong enough, the model's spectrum exhibits a peak at a periodicity related to the ocean's eddy-driven adjustment time. A nearly analytical approximation of the coupled model is used to study the sensitivity of this behavior to key model parameters.

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Section: Introductionmentioning

confidence: 99%

A mechanistic model of mid-latitude decadal climate variability

Kravtsov

Dewar

Ghil

et al. 2008

Physica D: Nonlinear Phenomena

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“…The linear response is expected to be weak, but nonlinear modes of atmospheric variability, such as SAM, may produce a stronger effect (Koo et al, 2002;Kravtsov et al, 2006a, b). Feliks et al (2004Feliks et al ( , 2007 have shown, in particular, how an oceanic thermal front may induce intraseasonal variability in the overlying atmosphere, including surfacewind evolution.…”

Section: Air-sea Coupling Over the Southern Oceanmentioning

confidence: 99%

An empirical stochastic model of sea-surface temperatures and surface winds over the Southern Ocean

et al. 2011

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Abstract. This study employs NASA's recent satellite measurements of sea-surface temperatures (SSTs) and sea-level winds (SLWs) with missing data filled-in by Singular Spectrum Analysis (SSA), to construct empirical models that capture both intrinsic and SST-dependent aspects of SLW variability. The model construction methodology uses a number of algorithmic innovations that are essential in providing stable estimates of the model's propagator. The best model tested herein is able to faithfully represent the time scales and spatial patterns of anomalies associated with a number of distinct processes. These processes range from the daily synoptic variability to interannual signals presumably associated with oceanic or coupled dynamics. Comparing the simulations of an SLW model forced by the observed SST anomalies with the simulations of an SLW-only model provides preliminary evidence for the ocean driving the atmosphere in the Southern Ocean region.

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“…Several time scales now interact: these include the intrinsic variability of the double-gyre circulation, on interannual and interdecadal time scales (Simonnet, 2005;Simonnet et al, 2005), as well as atmospheric LFV, on intraseasonal and interannual time scales (Feliks et al, 2004(Feliks et al, , 2007.…”

Section: Coupled Ocean-atmosphere Models Of the North Atlantic Circulmentioning

confidence: 99%

“…The oceanic model is then coupled with the atmosphere as in Feliks et al (2004Feliks et al ( , 2007, namely it is forced by the Gulf Stream's thermal front through the advected SST and associated Ekman pumping. The atmospheric domain is a periodic channel with two different settings, i.e.…”

Section: Coupled Ocean-atmosphere Models Of the North Atlantic Circulmentioning

confidence: 99%

“…First, following the results obtained by Feliks et al (2004; FGS-BT hereafter) a new and ambitious research program has been developed to study, in a systematic way, the influence of oceanic thermal fronts on the mid-latitude atmosphere. In particular, this program focuses on a hierarchy of models of increasing complexity, from barotropic quasi-geostrophic (QG) equations to full, coupled general circulation models (GCMs).…”

Section: Introductionmentioning

confidence: 99%

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Predictive Understanding of the Oceans' Wind-Driven Circulation on Interdecadal Time Scales

Igpp¹,

Feliks²,

Simonnet³

2008

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We provide here the final report corresponding to the physical part of this project. This part was directed by the P.I., Michael Ghil, at UCLA. The P.I. and collaborators, at UCLA and in France, have improved their understanding of mid-latitude atmospheric phenomena influenced by thermal oceanic fronts. They have also deepened the understanding of decadal variability of the oceans' double-gyre circulation. Prof. Roger Temam at Indiana University directed the mathematical part of the project, and the final report for this part was submitted in 2007. The physical part suffered in its third year from under-performance of a post-doc and thus required a no-cost extension. The results during the fourth and final year were more than satisfactory, as reported below. The final result is an emerging theory of the North Atlantic Oscillation and its downstream effects over Europe, the Mediterranean, and the Middle East.

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Low-Frequency Variability in the Midlatitude Atmosphere Induced by an Oceanic Thermal Front

Cited by 82 publications

References 52 publications

A mechanistic model of mid-latitude decadal climate variability

A mechanistic model of mid-latitude decadal climate variability

An empirical stochastic model of sea-surface temperatures and surface winds over the Southern Ocean

Predictive Understanding of the Oceans' Wind-Driven Circulation on Interdecadal Time Scales

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