This repository is the entry point for a collaborative project aiming at assessing the representation of ocean mesoscale variability in ocean models using SWOT altimeter data.
We propose a model intercomparison project to:
- Describe the seasonal variability of the mesoscale kinetic energy (KE) over the global ocean from SWOT altimeter.
- Evaluate the performance of a variety of numerical ocean models in capturing this variability.
- Better understand the main mechanisms driving the space and time variability of mesoscale ocean dynamics.
Mesoscale ocean dynamics are driven by mesoscale eddies, which are characterized by spatial and temporal scales around O(100 km) and O(10-100 days), respectively. Previous studies have shown that 80% of KE is concentrated at this scale (e.g., Chelton et al., 2011; Ferrari & Wunsch, 2009; Morrow & Le Traon, 2012; Wunsch, 2002, 2009; Klein et al., 2019). These structures play an important role in ocean circulation, air-sea interactions, global tracer transport and climate (e.g., Chelton et al., 2011; Morrow & Le Traon, 2012, Seo et al., 2023, McGillicuddy et al., 2008).
To describe the spatial and temporal variability of KE in the ocean, KE spectra have been widely used. Depending on the processes driving the dynamics, the slope of the KE spectrum varies (e.g. Scott & Wang 2005, Klein et al.; 2008). One of the main mechanisms of eddies production is associated with mean flow instabilities (Stammer & Wunsch, 1999, Morrow & Le Traon, 2012 ), and may be influenced by air-sea interactions, non-linear interactions (e.g., Scott & Wang, 2005, Seo et al., 2023, Von Storch et al., 2012). In situ observations, satellite altimetry and ocean numerical models show significant spatial and seasonal variability (e.g., Noh et al., 2007, Qiu et al., 2016; Callies et al., 2015; Torres et al., 2018).
Despite significant progress over the last decade, discrepancies in KE variability remain between prediction from geostrophic turbulence and observation from SSH altimetry (Klein et al., 2019). Furthermore, it is unclear whether the simulations adequately reproduce mesoscale variability, as well as the main mechanisms controlling spatial and temporal variability.
The Surface Water and Ocean Topography (SWOT) altimeter mission offers an unprecedented opportunity to document mesoscale variability and assess the ability of models to capture it. SWOT has a resolution of about 15 km depending on the region, allowing SSH to be described at smaller scales compared to previous altimetry datasets. In addition, there are 18 months of data available to date, allowing us to describe seasonal variability.
The aim of this project is to analyze the KE spectrum using SWOT SSH and several ocean simulations to describe the spatial and seasonal variability.
Interest research groups are invited to provide ocean model data following our data request.
Our group at IGE (Grenoble, France) will lead the analysis and share the results. All the communications will be orchestrated openly through GitHub. The end result of this effort will be a collective paper involving all contributors.
If you are interested, please raise a GitHub issue following our template.
We will request SSH data from the model equivalent to the SWOT dataset. We will provide the code for the calculation. Details will be communicated later.
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