Ocean surface current retrieval from space: The Sentinel-2 multispectral capabilities

Yurovskaya, Maria; Kudryavtsev, V. N.; Chapron, Bertrand; Collard, Fabrice

doi:10.1016/j.rse.2019.111468

Cited by 22 publications

(27 citation statements)

References 36 publications

(32 reference statements)

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“…We also note that the 1 m/s order of magnitude of the possible error on the current velocity is consistent with the spurious stripes appearing in maps of surface current estimated by Yurovskaya et al. (2019) and O(1 m) co‐registration errors found by Kääb et al. (2016).…”

Section: Effect Of Waves In Opposite Directions With Two‐image Sun Glint Methodssupporting

confidence: 91%

“…Following (Yurovskaya et al., 2019), we estimate U x and U y by a least squares fit to the measured phase differences after removing the linear wave dispersion,

ψ_{a} (k_{x}, k_{y}) = ((), ψ (k_{x}, k_{y}) - d t \sqrt{g \sqrt{k_{x}^{2} + k_{y}^{2}}}) / d t

which is related to the current vector ( U x , U y ) by

ψ_{a} (k_{x}, k_{y}) = k_{x} U_{x} + k_{y} U_{y} + ε (k_{x}, k_{y}),

where ɛ is a small residual. We only keep the M spectral components with index m corresponding to one pair ( k x , k y ) such that | k m | > 10 cpkm, | k m | < 40 cpkm and with std( ψ ) < 60°.…”

Section: Discussion: Consequences For Surface Current Velocity and Shear Retrievalmentioning

confidence: 99%

“…The angular distance α 1,2 is obtained from the law of cosines on the sphere,

\cos α_{1, 2} = \cos α_{1} \cos α_{2} + \sin α_{1} \sin α_{2} \cos (φ_{2} - φ_{1}) .

This typically gives distances and time lags within 1% of the expression given by Equation 1 in Yurovskaya et al. (2019).…”

Section: Effect Of Waves In Opposite Directions With Two‐image Sun Glint Methodsmentioning

confidence: 99%

“…(3) This typically gives distances and time lags within 1% of the expression given by Equation 1in Yurovskaya et al (2019).…”

Section: Short Waves In Opposing Directionsmentioning

confidence: 99%

“…This study does not address issues associated with systematic errors in the spatial registration on a global reference system with subpixel accuracy. These are partly discussed in Kääb et al (2016) and Yurovskaya et al (2019) and will be the topic of future work.…”

mentioning

confidence: 99%

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Total Surface Current Vector and Shear From a Sequence of Satellite Images: Effect of Waves in Opposite Directions

2021

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The Total Surface Current Velocity (TSCV) is the horizontal vector quantity that advects seawater, and it is an Essential Climate Variable that has been difficult to estimate from space. Following ground-based techniques, the TSCV can be derived from the phase speed of surface gravity waves, and the different estimates for different wavelengths are indicative of vertical shear that is of great interest. Here we combine satellite imagery and numerical simulation of the images to investigate the conditions in which shear could be measured. Using 10-m resolution images from the Level-1c Red Green and Blue channels of the Sentinel 2 Multispectral Instrument, acquired with time lags of 0.5 s, it is found that retrieving the near surface shear requires a specific attention to waves in opposing direction. Implementing a least-square fit in Fourier space of the current speed and amplitudes of waves in opposing directions to the observed complex amplitudes of a sequence of 3 images, the phase speed and current can be estimated much more accurately than with only a pair of images, down to the Nyquist wavelength of 20 m. A byproduct of this analysis is the "opposition spectrum" that is a key quantity in the sources of microseisms and microbaroms. A sensitivity analysis suggests that the retrieval of TSCV and shear can be improved by increasing time lags, increasing resolution and increasing the exposure time of acquisition, using a push-frame technique instead of MSI's push-broom technique. These finding open the way for new investigations of near-surface ocean processes including regions of freshwater influence and possibly internal waves.

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Section: Effect Of Waves In Opposite Directions With Two‐image Sun Glint Methodssupporting

confidence: 91%

“…Following (Yurovskaya et al., 2019), we estimate U x and U y by a least squares fit to the measured phase differences after removing the linear wave dispersion,

ψ_{a} (k_{x}, k_{y}) = ((), ψ (k_{x}, k_{y}) - d t \sqrt{g \sqrt{k_{x}^{2} + k_{y}^{2}}}) / d t

which is related to the current vector ( U x , U y ) by

ψ_{a} (k_{x}, k_{y}) = k_{x} U_{x} + k_{y} U_{y} + ε (k_{x}, k_{y}),

Section: Discussion: Consequences For Surface Current Velocity and Shear Retrievalmentioning

confidence: 99%

“…The angular distance α 1,2 is obtained from the law of cosines on the sphere,

\cos α_{1, 2} = \cos α_{1} \cos α_{2} + \sin α_{1} \sin α_{2} \cos (φ_{2} - φ_{1}) .

This typically gives distances and time lags within 1% of the expression given by Equation 1 in Yurovskaya et al. (2019).…”

Section: Effect Of Waves In Opposite Directions With Two‐image Sun Glint Methodsmentioning

confidence: 99%

“…(3) This typically gives distances and time lags within 1% of the expression given by Equation 1in Yurovskaya et al (2019).…”

Section: Short Waves In Opposing Directionsmentioning

confidence: 99%

mentioning

confidence: 99%

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Total Surface Current Vector and Shear From a Sequence of Satellite Images: Effect of Waves in Opposite Directions

2021

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Satellite Remote Sensing of Surface Winds, Waves, and Currents: Where are we Now?

et al. 2023

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This review paper reports on the state-of-the-art concerning observations of surface winds, waves, and currents from space and their use for scientific research and subsequent applications. The development of observations of sea state parameters from space dates back to the 1970s, with a significant increase in the number and diversity of space missions since the 1990s. Sensors used to monitor the sea-state parameters from space are mainly based on microwave techniques. They are either specifically designed to monitor surface parameters or are used for their abilities to provide opportunistic measurements complementary to their primary purpose. The principles on which is based on the estimation of the sea surface parameters are first described, including the performance and limitations of each method. Numerous examples and references on the use of these observations for scientific and operational applications are then given. The richness and diversity of these applications are linked to the importance of knowledge of the sea state in many fields. Firstly, surface wind, waves, and currents are significant factors influencing exchanges at the air/sea interface, impacting oceanic and atmospheric boundary layers, contributing to sea level rise at the coasts, and interacting with the sea-ice formation or destruction in the polar zones. Secondly, ocean surface currents combined with wind- and wave- induced drift contribute to the transport of heat, salt, and pollutants. Waves and surface currents also impact sediment transport and erosion in coastal areas. For operational applications, observations of surface parameters are necessary on the one hand to constrain the numerical solutions of predictive models (numerical wave, oceanic, or atmospheric models), and on the other hand to validate their results. In turn, these predictive models are used to guarantee safe, efficient, and successful offshore operations, including the commercial shipping and energy sector, as well as tourism and coastal activities. Long-time series of global sea-state observations are also becoming increasingly important to analyze the impact of climate change on our environment. All these aspects are recalled in the article, relating to both historical and contemporary activities in these fields.

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Exploring Fine-Scale Satellite-Derived Coastal Bathymetry for Ocean Modeling: A Case Study from West Africa

Marchesiello,

Thoumyre,

Dieye

et al. 2024

Estuaries and Coasts

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Ocean surface current retrieval from space: The Sentinel-2 multispectral capabilities

Cited by 22 publications

References 36 publications

Total Surface Current Vector and Shear From a Sequence of Satellite Images: Effect of Waves in Opposite Directions

Total Surface Current Vector and Shear From a Sequence of Satellite Images: Effect of Waves in Opposite Directions

Satellite Remote Sensing of Surface Winds, Waves, and Currents: Where are we Now?

Exploring Fine-Scale Satellite-Derived Coastal Bathymetry for Ocean Modeling: A Case Study from West Africa

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