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With an increase in computational power, ocean models with kilometer-scale resolution have emerged over the last decade. Using these realistic simulations, we have been able to quantify the energetic exchanges between spatial scales and inform the design of eddy parametrizations. The increase in resolution, however, has drastically increased model outputs, making it difficult to transfer and analyze the data. The realism of individual models in representing the energetics down to numerical dissipation has also come into question. Here, we showcase a cloud-based analysis framework proposed by the Pangeo Project that aims to tackle such distribution and analysis challenges. We analyze seven submesoscale permitting simulations all on the cloud at a crossover region of the upcoming SWOT altimeter mission near the Gulf Stream separation. The models used in this study are based on the NEMO, CROCO, MITgcm, HYCOM, FESOM and FIO-COM code bases. The cloud-based analysis framework: i) minimizes the cost of duplicating and storing ghost copies of data, and ii) allows for seamless sharing of analysis results amongst collaborators. In this poster, we will describe the framework and provide preliminary results (e.g. spectra, vertical buoyancy flux, and how it compares to predictions from the mixed-layer instability parametrization). Basin-to-global scale, submesoscale-permitting models are still at their early stage of development ; their cost and carbon footprints are also rather large. It would, therefore, benefit the community to compile the different model configurations for future best practices. We also believe that an emphasis on data analysis strategies would be crucial for improving the models themselves.

An ensemble of North Atlantic simulations is analyzed, providing estimates of kinetic energy spectra. A wavelet transform technique is used permitting comparisons to be made between spectra at different locations in this highly inhomogeneous environment. We find a strong tendency towards anisotropy in the spectra, with meridional spectra typically stronger than zonal spectra. This holds even in the gyre interior where conditions might be expected to be homogeneous. The spectra show reasonable ranges consistent with a downscale enstrophy cascade, but also a persistent tendency to exhibit steeper slopes at smaller scales. The only location where the presence of an upscale cascade is supported is the Gulf Stream extension. This is amongst first attempts to quantify and compare spectra and their differences in the inhomogeneous setting of the North Atlantic.

The analysis of eddy-mean flow interaction provides key insights into the structures and dynamics of inhomogeneous and anisotropic flows such as atmospheric and oceanic jets. As the divergence of Eliassen-Palm (E-P) flux formally encapsulates the interaction, the community has had a long-standing interest in accurately diagnosing this term. Here, we revisit the E-P flux divergence with an emphasis on the Gulf Stream, using a 48-member, eddy-rich (1/12°) ensemble of the North Atlantic ocean partially coupled to identical atmospheric states amongst all members via an atmospheric boundary layer model. This dataset allows for an unique decomposition where we define the mean flow as the ensemble mean, and interpret it as the oceanic response to the atmospheric state. The eddies are subsequently defined as fluctuations about the ensemble mean. Our results highlight two points: i) the implementation of the Thickness-Weighted Averaged (TWA) framework for a realistic ocean simulation in diagnosing the E-P flux divergence, and ii) validity of the ergodic assumption where one treats the temporal mean equivalent to the ensemble mean, which is questionable for a temporally varying system such as the ocean and climate.

The `eddying' ocean, recognized for several decades, has been the focus of much observational and theoretical research. We here describe a generalization for the analysis of eddy energy, based in the use of ensembles, that addresses two key related issues: the definition of an `eddy' and the general computation of energy spectra. An ensemble identifies eddies as the unpredictable component of the flow, and permits the scale decomposition of their energy in inhomogeneous and non-stationary settings. It also avoids the `tapering' or `windowing' of the data required by traditional approaches. We apply the analysis to a mesoscale resolving (1/12 degree) ensemble of the separated North Atlantic Gulf Stream. Our results show that the eddies are consistent with the theoretical predictions of quasi-geostrophy both at the surface and ocean interior.

With the advent of high-performance computing, we are now capable of simulating the ocean and climate system on decadal to centennial timescales. However, global and basin-scale simulations still lack the spatial resolution necessary to resolve the mesoscales (hereon referred to as mesoscale-permitting simulations), a scale roughly on the order of O(100 km). Here, we provide a first step towards a potential vorticity (PV) based mesoscale closure scheme in order to improve the representation of mesoscale eddies in such simulations by taking advantage of the thickness-weighted averaged (TWA) framework. In the TWA framework the total eddy feedback can be encapsulated in the Eliassen-Palm (E-P) flux divergence. This implies that mesoscale closure schemes aimed at representing the total eddy feedback should therefore be representing the E-P flux divergence. The TWA framework further elucidates that its divergence is equivalent to the eddy Ertel PV flux. In other words, if one is to parametrize the eddy Ertel PV flux, one has parametrized the total eddy feedback onto the mean flow. Using a 1/12° North Atlantic ensemble simulation with 24 members, which allows us to decompose the mesoscale variability from the forced dynamics, we show that the eddy Ertel PV flux can be related to the local-gradient of mean Ertel PV as an active tracer via an anisotropic eddy diffusivity tensor. What follows is that not only does the tensor bring together the isopycnal thickness skew diffusivity and isopycnic tracer diffusivity, the former known as the Gent-McWilliams (GM) parametrization and latter the Redi parametrization, but also incorporates the eddy momentum fluxes. Although the Redi parametrization has existed longer than GM, there has been much more development in the latter, leaving the Redi diffusivity poorly constrained. Being able to treat GM and Redi simultaneously is another strength of our framework.