High-Resolution Ocean Currents from Sea Surface Temperature Observations: The Catalan Sea (Western Mediterranean)

Isern‐Fontanet, Jordi; Garcı́a-Ladona, Emilio; González‐Haro, Cristina; Turiel, Antonio; Fieschi, Miquel Rosell; Company, Joan B.; Padial, Antonio Delgado

doi:10.3390/rs13183635

Cited by 8 publications

(6 citation statements)

References 39 publications

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“…To confirm this answer it would be necessary to analyze global numerical simulations (Su et al., 2020) or observations (Merchant et al., 2019). However, before using infrared SST measurements, it is necessary to address the problems generated by data gaps due to cloud coverage (Isern‐Fontanet et al., 2021); the masking out of strong fronts by the failure of cloud mask algorithms (Kilpatrick et al., 2019); and the changes in Δ h − induced by noise (Isern‐Fontanet & Hascoët, 2014). Among them, the most critical problem is the masking of strong fronts because it has a direct impact on the estimation of h ∞ and thus, Δ h − = h d − h ∞ .…”

Section: Discussionmentioning

confidence: 99%

On the Seasonal Cycle of the Statistical Properties of Sea Surface Temperature

Isern‐Fontanet

Capet

Turiel

et al. 2022

Geophysical Research Letters

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Sea Surface Temperature (SST) is a fundamental variable of the Earth climate system due to its role in regulating climate and weather (Deser et al., 2010) and its dynamical connection to ocean currents . Moreover, the availability of a long time series of global high resolution satellite measurements of SST (Merchant et al., 2019) makes it well suited for addressing a wide range of problems such as monitoring Climate Change (Gulev et al., 2021); retrieving ocean currents (Isern-Fontanet et al., 2017); or calibrating and validating ocean and climate models (Skákala et al., 2019). It is, therefore, of major importance to understand how ocean processes contribute to SST statistics to exploit such a wealth of data and get insight into the functioning of the ocean and climate.A prominent feature of SST is the presence of fronts, which are known to be sinks of energy (D'Asaro et al., 2011; and significantly contribute to the vertical transport of nutrients and, thus, to primary production (Mahadevan, 2016). The variability of the characteristics of fronts, such as the density of fronts or their intensity, are expected to be mirrored by the variability of some SST statistics. A popular approach is based on the spectral slope of SST because it can be connected to theories of turbulence. Nevertheless, they provide an incomplete framework, if only because different theories may predict the same slope (Callies & Ferrari, 2013) and the underlying turbulence regime may not change in spite of the seasonal changes in the properties of fronts.The structure functions of a turbulent variable, that is, the moments of the differences between two points, are also at the core of theories of turbulence (Pope, 2000) and extend the information provided by spectral slopes (Sukhatme et al., 2020;Yu et al., 2017). Moreover, the anomalous scaling of the power laws deduced from the structure functions, that is, its deviation from a straight line, can be related to the geometry of gradients making use of the multifractal framework . The relevance of this approach has already been demonstrated in the oceanic context (Isern-Fontanet et al., 2007), and it has been used to develop metrics for

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Section: Discussionmentioning

confidence: 99%

On the Seasonal Cycle of the Statistical Properties of Sea Surface Temperature

Isern‐Fontanet

Capet

Turiel

et al. 2022

Geophysical Research Letters

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“…To enrich the information given by the radars, we explore the feasibility of using chlorophyll-a (Chl-a) and sea surface temperature estimation in the region as tracers for the surface circulation. In fact, satellite-derived data provide an excellent tool for identifying circulation patterns at fine spatial and temporal resolution and several studies demonstrated the potential of ocean color and SST data to extract valuable information for tracking mesoscale and submesoscale features (e.g., [45][46][47][48][49][50]).…”

Section: Aim Of the Workmentioning

confidence: 99%

Using a Combination of High-Frequency Coastal Radar Dataset and Satellite Imagery to Study the Patterns Involved in the Coastal Countercurrent Events in the Gulf of Cadiz

Fanelli,

Gomiz Pascual,

Bruno-Mejías

et al. 2024

Remote Sensing

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This study exploits the combination of High-Frequency Coastal Radar (HFR) information with satellite-derived observations to characterize the patterns involved in the coastal countercurrents (CCCs) events in the Gulf of Cadiz (GoC), which is situated in the SW of the Iberian Peninsula. The westward alongshore currents are observed throughout the year, but the main drivers necessary to develop this flow and its extension in both parts of the basin are not fully clear. In order to identify the main physical processes (both local and remote) that induce the development of these countercurrents and to evaluate the connection of the circulation patterns between the eastern and the western part of the GoC, we make use of several data sources available for the region. First of all, a land-based system of HFR antennas located at four different sites of the GoC provides the velocity field of the surface circulation of the basin. To achieve a significant characterization of the CCCs in the Gulf, the dataset analyzed is processed by means of a series of operations, including the Empirical Orthogonal Functions (EOFs) analysis used to identify spatial and temporal variability of the flow, a low-pass filter used to isolate the sub-inertial signal of the current and temporal interpolation to fill in the missing values. Secondly, given the known importance of the zonal component of the local winds combined with the variations in the mean pressure at sea level over the Western Mediterranean during these events, time series of meteorological data are processed and correlated with the current velocity series via a statistical analysis. Finally, sea surface temperature fields and chlorophyll-a distribution patterns are used as tracers to obtain information on the extension of the countercurrents where HFR data are missing in four cases studied during the year 2017. The conducted analysis revealed the consistent occurrence of westward coastal currents throughout the year, driven in the most intense cases by a combination of the zonal component of the local wind and atmospheric pressure fluctuations over the Western Mediterranean Sea. During those events, CCCs reached the Portuguese side of the Gulf and facilitated the advection of biological material and warmer waters.

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“…In 2006, it was proposed to use the Surface Quasi-Geostrophic (SQG) theory to obtain estimations of subsurface dynamics from satellite measurements [46,47]. The validity of this approach was tested using infrared SST [48][49][50]; microwave [51,52]; and SSS [53] measurements. The main conclusion was that the SQG approach is better suited to reconstruct the ocean dynamics in the upper 500 m for energetic areas with deep mixed layer depths (MLD) [46,47,52,54,55].…”

Section: Introductionmentioning

confidence: 99%

Surface and Interior Dynamics of Arctic Seas Using Surface Quasi-Geostrophic Approach

et al. 2023

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This study assesses the capability of Surface Quasi-Geostrophy (SQG) to reconstruct the three-dimensional (3D) dynamics in four critical areas of the Arctic Ocean: the Nordic, Barents, East Siberian, and Beaufort Seas. We first reconstruct the upper ocean dynamics from TOPAZ4 reanalysis of sea surface height (SSH), surface buoyancy (SSB), and surface velocities (SSV) and validate the results with the geostrophic and total TOPAZ4 velocities. The reconstruction of upper ocean dynamics using SSH fields is in high agreement with the geostrophic velocities, with correlation coefficients greater than 0.8 for the upper 400 m. SSH reconstructions outperform surface buoyancy reconstructions, even in places near freshwater inputs from river discharges, melting sea ice, and glaciers. Surface buoyancy fails due to the uncorrelation of SSB and subsurface potential vorticity (PV). Reconstruction from surface currents correlates to the total TOPAZ4 velocities with correlation coefficients greater than 0.6 up to 200 m. In the second part, we apply the SQG approach validated with the reanalysis outputs to satellite-derived sea level anomalies and validate the results against in-situ measurements. Due to lower water column stratification, the SQG approach’s performance is better in fall and winter than in spring and summer. Our results demonstrate that using surface information from SSH or surface velocities, combined with information on the stratification of the water column, it is possible to effectively reconstruct the upper ocean dynamics in the Arctic and Subarctic Seas up to 400 m. Future remote sensing missions in the Arctic Ocean, such as SWOT, Seastar, WaCM, CIMR, and CRISTAL, will produce enhanced SSH and surface velocity observations, allowing SQG schemes to characterize upper ocean 3D mesoscale dynamics up to 400 m with higher resolutions and lower uncertainties.

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High-Resolution Ocean Currents from Sea Surface Temperature Observations: The Catalan Sea (Western Mediterranean)

Cited by 8 publications

References 39 publications

On the Seasonal Cycle of the Statistical Properties of Sea Surface Temperature

On the Seasonal Cycle of the Statistical Properties of Sea Surface Temperature

Using a Combination of High-Frequency Coastal Radar Dataset and Satellite Imagery to Study the Patterns Involved in the Coastal Countercurrent Events in the Gulf of Cadiz

Surface and Interior Dynamics of Arctic Seas Using Surface Quasi-Geostrophic Approach

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