Will high-resolution global ocean models benefit coupled predictions on short-range to climate timescales?

Hewitt, Helene T.; Bell, Michael; Chassignet, Eric P.; Czaja, Arnaud; Ferreira, David; Griffies, Stephen M.; Hyder, Pat; McClean, Julie L.; New, Adrian L.; Roberts, Malcolm

doi:10.1016/j.ocemod.2017.11.002

Cited by 93 publications

(96 citation statements)

References 176 publications

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“…However, there is increasing evidence that this is the case (e.g., Hallam et al, ). High‐resolution models can help to better understand the relationship between the AMOC and climate/weather timescales (e.g., Hewitt et al, ). Increasingly, these models can be run for many decades, sometimes even centuries, thus providing much longer time series for analysis.…”

Section: Discussion and Outlookmentioning

confidence: 99%

The Atlantic Meridional Overturning Circulation in High‐Resolution Models

et al. 2020

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The Atlantic meridional overturning circulation (AMOC) represents the zonally integrated stream function of meridional volume transport in the Atlantic Basin. The AMOC plays an important role in transporting heat meridionally in the climate system. Observations suggest a heat transport by the AMOC of 1.3 PW at 26°N-a latitude which is close to where the Atlantic northward heat transport is thought to reach its maximum. This shapes the climate of the North Atlantic region as we know it today. In recent years there has been significant progress both in our ability to observe the AMOC in nature and to simulate it in numerical models. Most previous modeling investigations of the AMOC and its impact on climate have relied on models with horizontal resolution that does not resolve ocean mesoscale eddies and the dynamics of the Gulf Stream/North Atlantic Current system. As a result of recent increases in computing power, models are now being run that are able to represent mesoscale ocean dynamics and the circulation features that rely on them. The aim of this review is to describe new insights into the AMOC provided by high-resolution models. Furthermore, we will describe how high-resolution model simulations can help resolve outstanding challenges in our understanding of the AMOC. Key Points:• Observations and high-resolution models have changed view on the AMOC pathways • High-resolution models suggest the presence of previously unknown high-frequency AMOC variability • High-resolution models allow to estimate the intrinsic/chaotic component of the AMOCCorrespondence to:

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Section: Discussion and Outlookmentioning

confidence: 99%

The Atlantic Meridional Overturning Circulation in High‐Resolution Models

et al. 2020

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“…It is important to note that other aspects of resolution such as ocean resolution or vertical atmospheric resolution were not tested in this study. Nevertheless, there is evidence that improved ocean resolution can improve the fidelity of simulations relevant to seasonal prediction (Scaife et al, 2011;Hewitt et al, 2017). In particular, higher ocean resolution may increase the strength of ocean-atmosphere coupling (Minobe et al, 2008;Kirtman et al, 2017), although there is as yet limited evidence for increased prediction skill from increased ocean resolution.…”

Section: Discussionmentioning

confidence: 99%

Does increased atmospheric resolution improve seasonal climate predictions?

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et al. 2019

Atmospheric Science Letters

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We assess the impact of atmospheric horizontal resolution on the prediction skill and fidelity of seasonal forecasts. We show the response to an increase of atmospheric resolution from 0.8 to 0.3° horizontal grid spacing in parallel ensembles of forecasts. Changes in the prediction skill of major modes of tropical El Nino Southern Oscillation (ENSO) and extratropical North Atlantic Oscillation (NAO) variability are small and not detected and there is no discernible impact on the weak signal‐to‐noise ratio in seasonal predictions of the winter NAO at this range of resolutions. Although studies have shown improvements in the simulation of tropical cyclones as model resolution is increased, we find little impact on seasonal prediction skill of either their numbers or intensity. Over this range of resolutions it appears that the benefit of increasing atmospheric resolution to seasonal climate predictions is minimal. However, at yet finer scales there appears to be increased eddy feedback which could strengthen weak signals in predictions of the NAO. Until prediction systems can be run operationally at these scales, it may be better to use additional computing resources for other enhancements such as increased ensemble size, for which there is a clear benefit in extratropical seasonal prediction skill.

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“…In general, these models improve on many of the shortcomings in coarser resolution, non-eddy resolving climate models, as described in a recent review (Hewitt et al 2017 and references therein). In particular, air-sea interaction in the Gulf Stream is improved in eddy-resolving coupled climate models, and hence, would be necessary to resolve also in dynamical prediction systems (Siqueira and Kirtman 2016).…”

Section: Discussionmentioning

confidence: 99%

Variability along the Atlantic water pathway in the forced Norwegian Earth System Model

et al. 2018

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The growing attention on mechanisms that can provide predictability on interannual-to-decadal time scales, makes it necessary to identify how well climate models represent such mechanisms. In this study we use a high (0.25° horizontal grid) and a medium (1°) resolution version of a forced global ocean-sea ice model, utilising the Norwegian Earth System Model, to assess the impact of increased ocean resolution. Our target is the simulation of temperature and salinity anomalies along the pathway of warm Atlantic water in the subpolar North Atlantic and the Nordic Seas. Although the high resolution version has larger biases in general at the ocean surface, the poleward propagation of thermohaline anomalies is better resolved in this version, i.e., the time for an anomaly to travel northward is more similar to observation based estimates. The extent of these anomalies can be rather large in both model versions, as also seen in observations, e.g., stretching from Scotland to northern Norway. The easternmost branch into the Nordic and Barents Seas, carrying warm Atlantic water, is also improved by higher resolution, both in terms of mean heat transport and variability in thermohaline properties. A more detailed assessment of the link between the North Atlantic Ocean circulation and the thermohaline anomalies at the entrance of the Nordic Seas reveals that the high resolution is more consistent with mechanisms that are previously published. This suggests better dynamics and variability in the subpolar region and the Nordic Seas in the high resolution compared to the medium resolution. This is most likely due a better representation of the mean circulation in the studied region when using higher resolution. As the poleward propagation of ocean heat anomalies is considered to be a key source of climate predictability, we recommend that similar methodology presented herein should be performed on coupled climate models that are used for climate prediction.

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Will high-resolution global ocean models benefit coupled predictions on short-range to climate timescales?

Abstract: Will high-resolution global ocean models benefit coupled predictions on short-range to climate timescales?,

Cited by 93 publications

References 176 publications

The Atlantic Meridional Overturning Circulation in High‐Resolution Models

The Atlantic Meridional Overturning Circulation in High‐Resolution Models

Does increased atmospheric resolution improve seasonal climate predictions?

Variability along the Atlantic water pathway in the forced Norwegian Earth System Model

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