Unsupervised Reconstruction of Sea Surface Currents from AIS Maritime Traffic Data Using Learnable Variational Models

The estimation of ocean dynamics is a key challenge for applications ranging from climate modeling to ship routing. State-of-the-art methods relying on satellite-derived altimetry data can hardly resolve spatial scales below ∼100 km. In this work we investigate the relevance of AIS data streams as a new mean for the estimation of the surface current velocities. Using a physics-informed observation model, we propose to solve the associated the ill-posed inverse problem using a trainable variational formulation. The latter exploits variational auto-encoders coupled with neural ODE to represent sea surface dynamics. We report numerical experiments on a real AIS dataset off South Africa in a highly dynamical ocean region. They support the relevance of the proposed learning-based AIS-driven approach to significantly improve the reconstruction of sea surface currents compared with state-of-the-art methods, including altimetry-based ones.

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Honing in on bioluminescent milky seas from space

Scientific Reports ◽

10.1038/s41598-021-94823-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Steven D. Miller ◽

Steven H. D. Haddock ◽

William C. Straka ◽

Curtis J. Seaman ◽

Cynthia L. Combs ◽

...

Keyword(s):

Scientific Inquiry ◽

Water Mass ◽

Marine Ecosystem ◽

Sea Surface ◽

Surface Currents ◽

Maritime Continent ◽

Low Light ◽

Composition Formation ◽

Mass Isolation ◽

New Generation

AbstractMilky seas are a rare form of marine bioluminescence where the nocturnal ocean surface produces a widespread, uniform and steady whitish glow. Mariners have compared their appearance to a daylit snowfield that extends to all horizons. Encountered most often in remote waters of the northwest Indian Ocean and the Maritime Continent, milky seas have eluded rigorous scientific inquiry, and thus little is known about their composition, formation mechanism, and role within the marine ecosystem. The Day/Night Band (DNB), a new-generation spaceborne low-light imager, holds potential to detect milky seas, but the capability has yet to be demonstrated. Here, we show initial examples of DNB-detected milky seas based on a multi-year (2012–2021) search. The massive bodies of glowing ocean, sometimes exceeding 100,000 km2 in size, persist for days to weeks, drift within doldrums amidst the prevailing sea surface currents, and align with narrow ranges of sea surface temperature and biomass in a way that suggests water mass isolation. These findings show how spaceborne assets can now help guide research vessels toward active milky seas to learn more about them.

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Controls of Caribbean surface hydrology during the mid- to late Holocene: insights from monthly resolved coral records

Climate of the Past ◽

10.5194/cp-9-841-2013 ◽

2013 ◽

Vol 9 (2) ◽

pp. 841-858 ◽

Cited By ~ 15

Author(s):

C. Giry ◽

T. Felis ◽

M. Kölling ◽

W. Wei ◽

G. Lohmann ◽

...

Keyword(s):

Late Holocene ◽

Hydrological Cycle ◽

Summer Precipitation ◽

Caribbean Sea ◽

Sea Surface ◽

Surface Currents ◽

Surface Hydrology ◽

Multidecadal Variability ◽

Southern Caribbean ◽

The Caribbean

Abstract. Several proxy-based and modeling studies have investigated long-term changes in Caribbean climate during the Holocene, however, very little is known on its variability on short timescales. Here we reconstruct seasonality and interannual to multidecadal variability of sea surface hydrology of the southern Caribbean Sea by applying paired coral Sr/Ca and δ18O measurements on fossil annually banded Diploria strigosa corals from Bonaire. This allows for better understanding of seasonal to multidecadal variability of the Caribbean hydrological cycle during the mid- to late Holocene. The monthly resolved coral Δδ18O records are used as a proxy for the oxygen isotopic composition of seawater (δ18Osw) of the southern Caribbean Sea. Consistent with modern day conditions, annual δ18Osw cycles reconstructed from three modern corals reveal that freshwater budget at the study site is influenced by both net precipitation and advection of tropical freshwater brought by wind-driven surface currents. In contrast, the annual δ18Osw cycle reconstructed from a mid-Holocene coral indicates a sharp peak towards more negative values in summer, suggesting intense summer precipitation at 6 ka BP (before present). In line with this, our model simulations indicate that increased seasonality of the hydrological cycle at 6 ka BP results from enhanced precipitation in summertime. On interannual to multidecadal timescales, the systematic positive correlation observed between reconstructed sea surface temperature and salinity suggests that freshwater discharged from the Orinoco and Amazon rivers and transported into the Caribbean by wind-driven surface currents is a critical component influencing sea surface hydrology on these timescales.

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Maritime Traffic Data Visualization: A Brief Review

2019 IEEE 4th International Conference on Big Data Analytics (ICBDA) ◽

10.1109/icbda.2019.8713227 ◽

2019 ◽

Cited By ~ 4

Author(s):

Kai Wang ◽

Maohan Liang ◽

Yan Li ◽

Jingxian Liu ◽

Ryan Wen Liu

Keyword(s):

Data Visualization ◽

Traffic Data ◽

Maritime Traffic

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On Capabilities of Tracking Marine Surface Currents Using Artificial Film Slicks

Remote Sensing ◽

10.3390/rs11070840 ◽

2019 ◽

Vol 11 (7) ◽

pp. 840 ◽

Cited By ~ 3

Author(s):

Ivan Kapustin ◽

Olga Shomina ◽

Alexey Ermoshkin ◽

Nikolay Bogatov ◽

Alexander Kupaev ◽

...

Keyword(s):

Water Film ◽

Remote Sensing Data ◽

Sea Surface ◽

Application Of Surfactants ◽

Surface Currents ◽

Band Formation ◽

Suggested Approach ◽

Marine Currents ◽

Sar Imagery ◽

Film Spreading

It is known that films on the sea surface can appear due to ship pollution, river and collector drains, as well as natural biological processes. Marine film slicks can indicate various geophysical processes in the upper layer of the ocean and in the atmosphere. In particular, slick signatures in SAR-imagery of the sea surface at low and moderate wind speeds are often associated with marine currents. Apart from the current itself, other factors such as wind and the physical characteristics of films can significantly influence the dynamics of slick structures. In this paper, a prospective approach aimed at measuring surface currents is developed. The approach is based on the investigation of the geometry of artificial banded slicks formed under the action of marine currents and on the retrieval of the current characteristics from this geometry. The developed approach is applied to quasi stationary slick bands under conditions when the influence of the film spreading effects can be neglected. For the stationary part of the slick band where transition processes of the band formation, e.g., methods of application of surfactants on water, film spreading processes, possible wind transformation etc., become negligible, some empirical relations between the band geometrical characteristics and the characteristics of the surface currents are obtained. The advantage of the approach is a possibility of getting information concerning the spatial structure of marine currents along the entire slick band. The suggested approach can be efficient for remote sensing data verification.

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A Synergetic Approach for the Space-Based Sea Surface Currents Retrieval in the Mediterranean Sea

Remote Sensing ◽

10.3390/rs11111285 ◽

2019 ◽

Vol 11 (11) ◽

pp. 1285 ◽

Cited By ~ 4

Author(s):

Daniele Ciani ◽

Marie-Hélène Rio ◽

Milena Menna ◽

Rosalia Santoleri

Keyword(s):

Numerical Model ◽

Mediterranean Sea ◽

Mediterranean Area ◽

Hf Radar ◽

Sea Surface ◽

Reconstruction Method ◽

Surface Currents ◽

Basin Scale ◽

The Mediterranean ◽

Sicily Channel

We present a method for the remote retrieval of the sea surface currents in the Mediterranean Sea. Combining the altimeter-derived currents with sea-surface temperature information, we created daily, gap-free high resolution maps of sea surface currents for the period 2012–2016. The quality of the new multi-sensor currents has been assessed through comparisons to other surface-currents estimates, as the ones obtained from drifting buoys trajectories (at the basin scale), or HF-Radar platforms and ocean numerical model outputs in the Malta–Sicily Channel. The study yielded that our synergetic approach can improve the present-day derivation of the surface currents in the Mediterranean area up to 30% locally, with better performances for the the meridional component of the motion and in the western section of the basin. The proposed reconstruction method also showed satisfying performances in the retrieval of the ageostrophic circulation in the Sicily Channel. In this area, assuming the High Frequency Radar-derived currents as reference, the merged multi-sensor currents exhibited improvements with respect to the altimeter estimates and numerical model outputs, mainly due to their enhanced spatial and temporal resolution.

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Validation of HF radar sea surface currents in the Malta-Sicily Channel

Remote Sensing of Environment ◽

10.1016/j.rse.2019.02.026 ◽

2019 ◽

Vol 225 ◽

pp. 65-76 ◽

Cited By ~ 7

Author(s):

Fulvio Capodici ◽

Simone Cosoli ◽

Giuseppe Ciraolo ◽

Carmelo Nasello ◽

Antonino Maltese ◽

...

Keyword(s):

Hf Radar ◽

Sea Surface ◽

Surface Currents ◽

Sicily Channel

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Wind currents, tidal streams and plankton off the Northumberland coast

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315400006950 ◽

1959 ◽

Vol 38 (3) ◽

pp. 529-541 ◽

Cited By ~ 3

Author(s):

Frank Evans

Keyword(s):

Water Flow ◽

Surface Region ◽

Sea Surface ◽

Surface Currents ◽

Total Water ◽

Tidal Streams ◽

Wind Currents

Investigations of the water movements off the southern Northumberland coast have until now been confined to the surface region. While important for navigational and similar purposes such investigations can give us no more than an indication of the total water flow along the coast nor can they elucidate the effects of currents on planktonic organisms which spend part or all of their existence away from the surface. It is for the latter reason that the series of investigations of sea surface currents made aboard the R.V. ‘Alexander Meek’ in 1956–7 (Evans, 1957) has now been supplemented by further series at two deeper levels.

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