Sensitivity of a double-gyre ocean model to details of stochastic forcing

Sura, Philip; Penland, Cécile

doi:10.1016/s1463-5003(02)00008-2

Cited by 22 publications

(20 citation statements)

References 43 publications

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“…Finally, we must choose whether to implement uncorrelated or autocorrelated noise, and in the latter case we must choose the decorrelation scales in time and space. Sura and Penland (2002) have emphasized that the details of stochastic perturbations introduced into numerical climate models must be physically justified to the fullest extent possible. To this end, high-resolution models may be regarded as truth and used to inform the choice of noise characteristics (Shutts and Palmer 2007).…”

Section: B Stochastic Noisementioning

confidence: 99%

“…It gives clear improvements in the skill of probabilistic predictions of precipitation (Buizza et al 1999(Buizza et al , 2005. Recently, there has been a growing interest in applying stochastic techniques to ocean models of the type used for longer-term seasonal forecasts and climate predictions (e.g., Sura and Penland 2002;Berloff 2005a;Berloff et al 2007;Li and von Storch 2013;Porta Mana and Zanna 2014;Jansen and Held 2014;Kitsios et al 2014;Andrejczuk et al 2016). Dawson and Palmer (2015) have shown that it may not be necessary to represent the small scales accurately, or even explicitly, in order to improve the simulation of the large-scale climate.…”

Section: Introductionmentioning

confidence: 99%

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Improved Climate Simulations through a Stochastic Parameterization of Ocean Eddies

et al. 2016

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In climate simulations, the impacts of the subgrid scales on the resolved scales are conventionally represented using deterministic closure schemes, which assume that the impacts are uniquely determined by the resolved scales. Stochastic parameterization relaxes this assumption, by sampling the subgrid variability in a computationally inexpensive manner. This study shows that the simulated climatological state of the ocean is improved in many respects by implementing a simple stochastic parameterization of ocean eddies into a coupled atmosphere-ocean general circulation model. Simulations from a highresolution, eddy-permitting ocean model are used to calculate the eddy statistics needed to inject realistic stochastic noise into a low-resolution, non-eddy-permitting version of the same model. A suite of four stochastic experiments is then run to test the sensitivity of the simulated climate to the noise definition by varying the noise amplitude and decorrelation time within reasonable limits. The addition of zero-mean noise to the ocean temperature tendency is found to have a nonzero effect on the mean climate. Specifically, in terms of the ocean temperature and salinity fields both at the surface and at depth, the noise reduces many of the biases in the low-resolution model and causes it to more closely resemble the highresolution model. The variability of the strength of the global ocean thermohaline circulation is also improved. It is concluded that stochastic ocean perturbations can yield reductions in climate model error that are comparable to those obtained by refining the resolution, but without the increased computational cost. Therefore, stochastic parameterizations of ocean eddies have the potential to significantly improve climate simulations.

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Section: B Stochastic Noisementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Improved Climate Simulations through a Stochastic Parameterization of Ocean Eddies

et al. 2016

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“…The wind stress over the midlatitude oceans displays strict periodic components but otherwise is quite a largeamplitude noisy signal (Schmeits and Dijkstra 2001;Sura 2003). For the North Pacific, the spatial correlation scale is found to be about 1000 km and a typical decorrelation time scale is about one day (Sura 2003). The effect of additive, spatially coherent and temporally white noise on the behavior of the DG flows has been studied in a reduced gravity model (Sura et al 2000(Sura et al , 2001.…”

Section: Introductionmentioning

confidence: 99%

Interaction of Additive Noise and Nonlinear Dynamics in the Double-Gyre Wind-Driven Ocean Circulation

Sapsis

Dijkstra

2013

Journal of Physical Oceanography

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In this paper the authors study the interactions of additive noise and nonlinear dynamics in a quasigeostrophic model of the double-gyre wind-driven ocean circulation. The recently developed framework of dynamically orthogonal field theory is used to determine the statistics of the flows that arise through successive bifurcations of the system as the ratio of forcing to friction is increased. This study focuses on the understanding of the role of the spatial and temporal coherence of the noise in the wind stress forcing. When the wind stress noise is temporally white, the statistics of the stochastic double-gyre flow does not depend on the spatial structure and amplitude of the noise. This implies that a spatially inhomogeneous noise forcing in the wind stress field only has an effect on the dynamics of the flow when the noise is temporally colored. The latter kind of stochastic forcing may cause more complex or more coherent dynamics depending on its spatial correlation properties.

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“…The random-forcing approach for rectification pattern has to form, because correlation between the relative vorticity and the latitude is always zero (Cummins, 1992;Wang and Vallis, 1994). Finally, it has been found that statistical details of random forcing-rarely analyzed and discussed-are qualitatively important for the dynamic response, therefore they must be physically constrained and more thoroughly studied (Treguier and Hua, 1987;Sura and Penland, 2002).…”

Section: Introductionmentioning

confidence: 99%

On rectification of randomly forced flows

Berloff¹

2005

J Mar Res

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Nonlinear rectification of the ocean circulation driven by random forcing, which simulates the effect of unresolved eddies, is studied in an idealized closed basin. The results are based on the analysis of randomly forced solutions and linear eigenmodes. Depending on the forcing strength, two rectification regimes are found: zonal jets and isolated gyres. It is shown that both regimes are due to nonlinear interactions of resonant basin modes. In the zonal-jet regime, these interactions involve complex interplay between resonant baroclinic modes and some secondary modes. Both Rhines' scaling for zonal jets and prediction of gyres based on the maximum entropy argument are not confirmed.

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Sensitivity of a double-gyre ocean model to details of stochastic forcing

Cited by 22 publications

References 43 publications

Improved Climate Simulations through a Stochastic Parameterization of Ocean Eddies

Improved Climate Simulations through a Stochastic Parameterization of Ocean Eddies

Interaction of Additive Noise and Nonlinear Dynamics in the Double-Gyre Wind-Driven Ocean Circulation

On rectification of randomly forced flows

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