The Andrea Wave Characteristics of a Measured North Sea Rogue Wave

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Anne Karin Magnusson ◽  
Mark A. Donelan
Keyword(s):  
North Sea ◽  
Rogue Wave ◽  
Order Theory ◽  
Second Order ◽  
Exceedance Probability ◽  
Sea Spray ◽  
Average Intensity ◽  
Laser Altimeter ◽  
The North ◽  
The One

Wave profiles have been measured with a system of four Optech lasers mounted on a bridge at the oil production site Ekofisk in the central North Sea since 2003, operated by ConocoPhillips. A double rogue wave was measured on Nov. 9, 2007 in a storm crossing the North Sea and named Andrea following a forecasting procedure between the Norwegian Meteorological Institute and ConocoPhillips. This wave, named here the “Andrea wave,” is comparable in height and characteristics to the well known Newyear wave (or Draupner wave) measured in 1995 by Statoil. Front steepness is higher. That the same profile is measured by all four lasers is a good indication that the shape of the wave has been captured correctly, but one may still ask if this crest is that of blue, green, or white water. That is, how much of the height is related to presence of foam or sea spray? We attempt to answer this using the information of intensity of the return signals, which has been related to wave breaking and sea spray in recent studies by Toffoli et al. (2011, “Estimating Sea Spray with a Laser Altimeter,” J. Atmos. Oceanic Technol., 28(9), pp. 1177–1183). Measurements of the average intensity of the return signal do not indicate presence of sea spray in the incoming part of the wave, but high intensity of return after the passage of the crest indicates presence of sea spray or foam on the parts of the waves exposed to winds. Cameras following the sea surface at measuring position with information on the return signal as given here would most probably increase our understanding of what is measured. Exceedance probability of crests and heights show a deviation from the second order distribution as given by Forristall (2000, “Wave Crests Distributions: Observations and Second-Order Theory,” J. Phys. Oceanogr. 30(8), pp. 1931–1943) for the one percent highest waves in an apparently stable 3 h period including the Andrea wave. The deviation already starts at crest/Hs factors around 1.0.

scholarly journals New sperm whale remains from the late Miocene of the North Sea and a revised family attribution for the small crown physeteroid Thalassocetus Abel, 1905

2021 ◽  
Author(s):  
Apolline ALFSEN ◽  
Mark BOSSELAERS ◽  
Olivier LAMBERT
Keyword(s):  
North Sea ◽  
Late Miocene ◽  
Sperm Whale ◽  
Close Relative ◽  
Sperm Whales ◽  
The North ◽  
The Family ◽  
The North Sea ◽  
Early Radiation ◽  
The One

In spite of a continuously expanding physeteroid fossil record, our understanding of the origin and early radiation of the two modern sperm whale families Kogiidae Gill, 1871 (including the pygmy and dwarf sperm whales, Kogia spp.) and Physeteridae Gray, 1821 (including the great sperm whale, Physeter Linnaeus, 1758) remains limited, especially due to the poorly resolved phylogenetic relationships of a number of extinct species. Among those, based on fragmentary cranial material from the late early to middle Miocene of Antwerp (Belgium, North Sea basin), the small-sized Thalassocetus antwerpiensis Abel, 1905 has been recognized for some time as the earliest branching kogiid. The discovery of a new diminutive physeteroid cranium from the late Miocene (Tortonian) of Antwerp leads to the description and comparison of a close relative of T. antwerpiensis. Thanks to the relatively young ontogenetic stage of this new specimen, the highly modified plate-like bones making the floor of its supracranial basin could be individually removed, a fact that greatly helped deciphering their identity and geometry. Close morphological similarities with T. antwerpiensis allow for the reassessment of several facial structures in the latter; the most important reinterpretation is the one of a crest-like structure, previously identified as a sagittal facial crest, typical for kogiids, and here revised as the left posterolateral wall of the supracranial basin, comprised of the left nasal (lost in kogiids for which the postnarial region is known) and the left maxilla. Implemented in a phylogenetic analysis, the new anatomical interpretations result in the new Belgian specimen and T. antwerpiensis being recovered as sister-groups in the family Physeteridae. Consequently, the geologically oldest kogiids are now dated from the Tortonian, further extending the ghost lineage separating these early late Miocene kogiid records from the estimated latest Oligocene to earliest Miocene divergence of kogiids and physeterids.

scholarly journals The North Sea Andrea storm and numerical simulations

2014 ◽  
Vol 14 (6) ◽  
pp. 1407-1415 ◽  
Author(s):  
E. M. Bitner-Gregersen ◽  
L. Fernandez ◽  
J. M. Lefèvre ◽  
J. Monbaliu ◽  
A. Toffoli
Keyword(s):  
Numerical Simulations ◽  
North Sea ◽  
Rogue Wave ◽  
Grid Point ◽  
Wave Model ◽  
Wave Statistics ◽  
The North ◽  
Nonlinear Phase ◽  
Spectral Wave Model ◽  
The North Sea

Abstract. A coupling of a spectral wave model with a nonlinear phase-resolving model is used to reconstruct the evolution of wave statistics during a storm crossing the North Sea on 8–9 November 2007. During this storm a rogue wave (named the Andrea wave) was recorded at the Ekofisk field. The wave has characteristics comparable to the well-known New Year wave measured by Statoil at the Draupner platform 1 January 1995. Hindcast data of the storm at the nearest grid point to the Ekofisk field are here applied as input to calculate the evolution of random realizations of the sea surface and its statistical properties. Numerical simulations are carried out using the Euler equations with a higher-order spectral method (HOSM). Results are compared with some characteristics of the Andrea wave record measured by the down-looking lasers at Ekofisk.

scholarly journals Did the Draupner wave occur in a crossing sea?

2011 ◽  
Vol 467 (2134) ◽  
pp. 3004-3021 ◽  
Author(s):  
T. A. A. Adcock ◽  
P. H. Taylor ◽  
S. Yan ◽  
Q. W. Ma ◽  
P. A. E. M. Janssen
Keyword(s):  
Low Frequency ◽  
Quality Measurement ◽  
Order Theory ◽  
Second Order ◽  
Flow Solver ◽  
The North ◽  
Highly Nonlinear ◽  
Nonlinear Potential ◽  
Wind Sea ◽  
Set Up

The ‘New Year Wave’ was recorded at the Draupner platform in the North Sea and is a rare high-quality measurement of a ‘freak’ or ‘rogue’ wave. The wave has been the subject of much interest and numerous studies. Despite this, the event has still not been satisfactorily explained. One piece of information that was not directly measured at the platform, but which is vital to understanding the nonlinear dynamics is the wave's directional spreading. This paper investigates the directionality of the Draupner wave and concludes it might have resulted from two wave-groups crossing, whose mean wave directions were separated by about 90 ° or more. This result has been deduced from a set-up of the low-frequency second-order difference waves under the giant wave, which can be explained only if two wave systems are propagating at such an angle. To check whether second-order theory is satisfactory for such a highly nonlinear event, we have run numerical simulations using a fully nonlinear potential flow solver, which confirm the conclusion deduced from the second-order theory. This is backed up by a hindcast from European Centre for Medium-Range Weather Forecasts that shows swell waves propagating at approximately 80 ° to the wind sea. Other evidence that supports our conclusion are the measured forces on the structure, the magnitude of the second-order sum waves and some other instances of freak waves occurring in crossing sea states.

scholarly journals Differentiation between two epilittoral species, Scutovertex arenocolus spec. nov. and Scutovertex pilosetosus Polderman (Acari: Oribatida) from different European coasts

Zootaxa ◽  
2009 ◽  
Vol 2153 (1) ◽  
pp. 35-54 ◽  
Author(s):  
TOBIAS PFINGSTL ◽  
SYLVIA SCHÄFFER ◽  
ERNST EBERMANN ◽  
GUENTHER KRISPER
Keyword(s):  
North Sea ◽  
Principal Component ◽  
Morphological Characters ◽  
Closely Related Species ◽  
The North ◽  
Baltic Coast ◽  
The North Sea ◽  
The One ◽  
The Baltic ◽  
Littoral Species

Scutovertex arenocolus spec. nov. living in the sandy shore of the Baltic coast is described. Additionally, a closely related species, S. pilosetosus, occurring in marsh habitats of the North Sea coast, is redescribed in detail. Both species show a similar habitus. Scutovertex arenocolus differs from S. pilosetosus in the length of body, cusps and notogastral setae, in the ridge on mentum as well as in a different exochorion structure of the eggs. A morphometric analysis of 14 morphological characters confirmed distinctly shorter cusps and notogastral setae in S. arenocolus. Additionally, a principal component analysis performed with 17 morphological traits provided a clear separation of these two species and of S. minutus. The results of these analyses lead to the conclusion that earlier reports of S. minutus in the coastal zone of the Atlantic, the Baltic and the North Sea should be assigned to the one or the other of these two littoral species.

A mathematical model of a river—shallow sea system used to investigate tide, surge and their interaction in the Thames—southern North Sea region

1974 ◽  
Vol 275 (1255) ◽  
pp. 567-609 ◽  
Keyword(s):  
Mathematical Model ◽  
Sea Level ◽  
North Sea ◽  
Southern Bight ◽  
The North ◽  
Open Sea ◽  
The North Sea ◽  
Good Potential ◽  
Tidal Oscillation ◽  
The One

A mathematical model is used to reproduce tidal and surge motion in the Thames Estuary and the Southern Bight of the North Sea. The model is based on a numerical finite-difference solution of the nonlinear hydrodynamical equations representing motion in the area. The equations are nonlinear in so far as they include quadratic bottom friction and allow for time variations in the total depth of water; the inclusion of advective terms is limited to the river. Solution of the one-dimensional equations for the river and the two-dimensional equations for the sea takes place within a single computational array. The scheme for calculating motion in the sea is similar to that developed by Heaps (1969), and the scheme for the river was developed by Rossiter & Lennon (1965). Tidal and surge motion within the model are reproduced by specifying the initial tidal contours of the sea, the external influences of surge and tidal oscillation along the open sea boundaries, and wind stresses over the sea surface. Computations have been concerned with generating lunar tidal oscillations for the construction of an M2 co-tidal chart, and investigating the interaction between tides and surges, in this region of shallow waters. The investigation of interaction involved calculating the sea’s response to the separate and combined effects of tidal and meteorological forces, whence the effects of a tide on a surge were deduced, possibly for the first time at offshore locations. Computed interaction phenomena for the period of a severe storm surge, 15 to 17 February 1962, were found to accord with the results of Proudman (19550, b, J957) and Rossiter (1961). Agreement between computed sea-level disturbances and actually recorded disturbances for this surge period revealed that the model has good potential for simulating sea level disturbances which occur in nature.

2. On the Destructive Effects of the Waves of the Sea on the North-East Shores of Shetland

1862 ◽  
Vol 4 ◽  
pp. 200-201
Author(s):  
Thomas Stevenson
Keyword(s):  
North Sea ◽  
Present Communication ◽  
North East ◽  
The North ◽  
The North Sea ◽  
The One ◽  
The Waves

The author stated, that the present communication might be regarded as supplementary to the one describing the results of his marine dynamometer, which would be found in the 14th volume of the “Transactions.” On the Bound Skerry of Whalsey, which is only exposed to the waves of the North Sea or German Ocean, he had found, on first landing in 1852, masses of rock, weighing 9½ tons and under, heaped together by the action of the waves at the level of no less than 62 feet above the sea; and others, ranging from 6 to 13½ tons, were found to have been quarried out of their positions in situ, at levels of from 70 to 74 feet above the sea.

Accident Black Spots in the Lower North Sea

1970 ◽  
Vol 23 (1) ◽  
pp. 108-118
Author(s):  
L. Oudet
Keyword(s):  
Traffic Flow ◽  
North Sea ◽  
Road Traffic ◽  
Black Spot ◽  
The North ◽  
Black Spots ◽  
North Eastern ◽  
The One

In this paper Commandant Oudet, who might well be called the architect of routing in the Dover Strait, discusses certain aspects of what has come to be known as the Sandettie problem, namely the emergence of a potential accident black spot at the north-eastern extremity of the one-way routes in the Strait. Various solutions are discussed, including the reversal of the direction of traffic flow in the Strait recently proposed by the Honourable Company of Master Mariners and supported by Trinity House. Commandant Oudet shows that this proposal, unless the direction of flow were reversed in adjoining traffic separation schemes, would have the effect of greatly increasing the number of crossings and encounters outside the Strait. ‘The remedy would be worse than the disease’, he concludes. ‘It would be better to abandon traffic separation altogether’.Places where road traffic is particularly dangerous and congested are often referred to as accident black spots; and the term is beginning to be used in the same sense in a navigational context. At sea an excessive density traffic always involves danger, because it is impossible to build fly-overs, as on land, and so avoid crossings; all encounters and all crossings take place on the same plane.

The Set-Down and Set-Up of Directionally Spread and Crossing Surface Gravity Wave Groups in Severe North Sea Storms

2018 ◽  
Author(s):  
Mark L. McAllister ◽  
Thomas A. A. Adcock ◽  
Ton S. van den Bremer ◽  
Paul H. Taylor
Keyword(s):  
Free Surface ◽  
North Sea ◽  
Water Depth ◽  
Order Theory ◽  
Relative Magnitude ◽  
Second Order ◽  
Experimental Results ◽  
Surface Gravity Wave ◽  
Wave Groups ◽  
Set Up

Recent work by McAllister et al. (2018) [1] has experimentally confirmed that the set-down of the wave-averaged free surface, first described by Longuet-Higgins and Stewart (1962) [2], can turn into a set-up when wave groups are sufficiently spread or cross at large angles. Experimental results were shown to agree well with second-order theory, including frequency-sum and frequency-difference terms, where the latter are responsible for the wave-averaged free surface. In this paper, we review these experimental results and examine theoretically the magnitude of the wave-averaged free surface in realistic extreme North Sea conditions. Specifically, we examine the role of the shape of the spectrum, water depth, and the relative magnitude of the peak frequencies of the two crossing groups. We find that having a realistic spectrum (JONSWAP vs. Gaussian) considerably enhances the magnitude of the second-order contribution, the total second-order signal increases with decreasing depth and can display a maximum provided the water depth is shallow enough for small to moderate degrees of spreading or crossing angles and is larger for spectral peaks that are further apart.

Estimating Sea Spray Volume with a Laser Altimeter

2011 ◽  
Vol 28 (9) ◽  
pp. 1177-1183 ◽  
Author(s):  
A. Toffoli ◽  
A. V. Babanin ◽  
M. A. Donelan ◽  
B. K. Haus ◽  
D. Jeong
Keyword(s):  
Laser Radiation ◽  
Water Surface ◽  
Sea Spray ◽  
Average Intensity ◽  
Laser Altimeter ◽  
Indirect Measure ◽  
Simple Regression Model ◽  
Spray Droplets ◽  
Laser Altimeters ◽  
Spray Volume

Abstract Down-looking laser altimeters are commonly used to measure the sea surface elevation. However, because the laser radiation is attenuated by spray droplets suspended along the transmission path, it is presumed that altimeters may also provide an indirect measure of the sea spray volume. Here, this conjecture is discussed by means of laboratory experiments, which have been conducted in a wind-wave flume. A large number of wind conditions were considered between equivalent 10-m wind speeds of 20 and 60 m s−1 in order to generate different spray volumes above the water surface. The facility was equipped with a laser and side-looking camera system to estimate the spray volume as well as a nearby down-looking laser altimeter. Results confirm that there is a robust degradation of the laser intensity for increasing wind speed and hence the amount of spray droplets above the water surface. A simple regression model to extract spray volume from the average intensity of the laser radiation is presented, demonstrating the promise of laser altimeters for making in situ spray observations. Additional observations will be required to calibrate the altimeters for applications in the open ocean marine environment.

scholarly journals A comparison of the measured North Sea Andrea rogue wave with numerical simulations

2013 ◽  
Vol 1 (5) ◽  
pp. 5033-5056 ◽  
Author(s):  
E. M. Bitner-Gregersen ◽  
L. Fernandez ◽  
J. M. Lefèvre ◽  
J. Monbaliu ◽  
A. Toffoli
Keyword(s):  
North Sea ◽  
Rogue Wave ◽  
Wave Model ◽  
Sea Surface ◽  
Wave Statistics ◽  
The North ◽  
Nonlinear Phase ◽  
Spectral Wave Model ◽  
Wave Event ◽  
The North Sea

Abstract. A coupling of a spectral wave model with a nonlinear phase resolving model is used to reconstruct the evolution of wave statistics during a storm crossing the North Sea on 8–9 November 2007. During this storm a rogue wave (named the Andrea wave) was recorded at the Ekofisk field. The wave has characteristics comparable to the well-known New Year wave measured by Statoil at the Draupner platform the 1 January 1995. Hindcast data of the storm are here applied as input to calculate random realizations of sea surface and evolution of its statistical properties associated with this specific wave event by solving the Euler equations with a Higher Order Spectral Method (HOSM). The numerical results are compared with the Andrea wave profile as well as characteristics of the Andrea wave record measured by the down-looking lasers at the Ekofisk field.

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