Influence from ‘Ocean Weather’ on near seabed currents and events at Ormen Lange

Alendal, Guttorm; Berntsen, Jarle; Engum, Elisabeth; Furnes, Gunnar Κ.; Kleiven, Gudmund; Eide, Lars Ingolf

doi:10.1016/j.marpetgeo.2004.10.011

Cited by 26 publications

(17 citation statements)

References 10 publications

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“…ζ max is then reaching approximately −325 m depth, which is approximately 225 m above the undisturbed ζ m interface. It may be noted that vertical displacements of the density surfaces of approximately 200 m are observed near the slope in the Nordic Seas, see Mork (1972) and Alendal et al (2005).…”

Section: Resultsmentioning

confidence: 99%

“…1, measurements from the Ormen Lange area and the Svinøy section have revealed several occurrences of high current speeds near the seabed Yttervik and Furnes 2005;Thiem et al 2006a). The strong currents are often associated with fluctuations in temperature and salinity due to traveling atmospheric low pressures as discussed in Vikebø et al (2004), Alendal et al (2005) and Thiem et al (2006a). However, some of the events occurred in periods with weak atmospheric forcing, and these were difficult to relate directly to the low pressure activity.…”

Section: The Norwegian Seamentioning

confidence: 99%

“…To generate the depressions of the density surfaces near the slope with amplitudes corresponding to the observed, see Mork (1972), Alendal et al (2005), Thiem et al (2006a), the model is initialized with a depressed internal solitary wave over the flat bottom ocean away from the slope. This internal solitary wave will first propagate over the deep flat ocean bottom towards the slope before starting to interact with the slope.…”

Section: Numerical Studies Of Shoaling and Breakingmentioning

confidence: 99%

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Numerical studies of large-amplitude internal waves shoaling and breaking at shelf slopes

Thiem¹,

Berntsen

2009

Ocean Dynamics

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Hydro carbon fields beyond the shelf break are presently being explored and developed, which has increased the scientific focus in this area. Measurements from the slopes reveal large variability in temperature and velocity, and some of the observed events are due to interactions between large-amplitude oscillations of the thermocline and the topography. The present study focuses on the strong currents that are generated near the seabed during shoaling and breaking of internal waves along shelf slopes. The parameter regime used is similar to the one for the Nordic Seas. The results show that, during shoaling of large internal waves along (gentle) slopes, the energy is transferred towards smaller scales and strong velocities (over 1 m s −1 ) can be generated. To resolve all scales involved is still not feasible, and therefore, the model results are sensitive to the grid size and the subgrid scale closure.

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Section: Resultsmentioning

confidence: 99%

Section: The Norwegian Seamentioning

confidence: 99%

Section: Numerical Studies Of Shoaling and Breakingmentioning

confidence: 99%

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Numerical studies of large-amplitude internal waves shoaling and breaking at shelf slopes

Thiem¹,

Berntsen

2009

Ocean Dynamics

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“…This has the possible interpretation that the event is caused by a sloshing motion across the NAC at the position. Atmospheric forcing may initiate such a sloshing motion (Vikebø et al 2004;Alendal et al 2005). (If h 2 = 550 m is used as length scale, the duration becomes 24hrs 262 h 2 /g .…”

Section: Discussionmentioning

confidence: 99%

“…Gjevik et al 1990;Aldrigde and Davies 1993;Davies and Aldridge 1993). Numerical modelling of the coastal currents represents several challenges, including the application of topographically following coordinate systems Thiem and Berntsen 2006) and resolution near the sea bed (Alendal et al 2005). The barotropic flow on the shelf (Gjevik et al 2002) and eddy generation by flow instability at the shelf edge (Davies et al 2003) contribute to the current picture.…”

Section: Introductionmentioning

confidence: 99%

A scaling law of internal run-up duration

Grue

Sveen

2010

Ocean Dynamics

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Wave tank experiments with long internal waves of elevation, of different initial length l, moving in a two-fluid system, interacting with a weak slope of 0.045 rad, show an onshore flow of the dense water, at the undisturbed pycnocline-slope intersection, of duration 11.3 l/g (g reduced gravity). This period corresponds to that of a strong bottom current event measured in the stratified ocean at the Ormen Lange gas field, at 850 m depth, lasting for 24 hrs, corresponding to 11.2 l/g , using the width l = 300 km of the Norwegian Atlantic Current (NAC) at the site as length scale, suggesting a lateral sloshing motion of the NAC causing the event. The onshore velocity of the dense fluid has a maximal velocity of 0.4 g h 2 in laboratory and 0.5 ms −1 = 0.3 g h 2 in the field (h 2 mixed upper layer thickness). Run-up of the dense fluid, beyond the undisturbed pycnocline-slope intersection, has initially a front velocity of 0.35 g h 2 , corresponding to the velocity of the head of a density current on a flat bottom. Due to disintegration, an initially depressed pycnocline results in comparatively smaller run-up and velocity. While moving past the turning point, a dispersive wave train is formed in the back part of the depression wave, developing by breaking into a sequence of up to eight boluses moving by the undisturbed pycnocline-slope intersection.

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Simulating spatial and temporal varying CO₂ signals from sources at the seafloor to help designing risk‐based monitoring programs

et al. 2016

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Risk‐based monitoring requires quantification of the probability of the design to detect the potentially adverse events. A component in designing the monitoring program will be to predict the varying signal caused by an event, here detection of a gas seep through the seafloor from an unknown location. The Bergen Ocean Model (BOM) is used to simulate dispersion of CO2 leaking from different locations in the North Sea, focusing on temporal and spatial variability of the CO2 concentration. It is shown that the statistical footprint depends on seep location and that this will have to be accounted for in designing a network of sensors with highest probability of detecting a seep. As a consequence, heterogeneous probabilistic predictions of CO2 footprints should be available to subsea geological CO2 storage projects in order to meet regulations.

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Influence from ‘Ocean Weather’ on near seabed currents and events at Ormen Lange

Cited by 26 publications

References 10 publications

Numerical studies of large-amplitude internal waves shoaling and breaking at shelf slopes

Numerical studies of large-amplitude internal waves shoaling and breaking at shelf slopes

A scaling law of internal run-up duration

Simulating spatial and temporal varying CO₂ signals from sources at the seafloor to help designing risk‐based monitoring programs

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Influence from ‘Ocean Weather’ on near seabed currents and events at Ormen Lange

Cited by 26 publications

References 10 publications

Numerical studies of large-amplitude internal waves shoaling and breaking at shelf slopes

Numerical studies of large-amplitude internal waves shoaling and breaking at shelf slopes

A scaling law of internal run-up duration

Simulating spatial and temporal varying CO2 signals from sources at the seafloor to help designing risk‐based monitoring programs

Contact Info

Product

Resources

About

Simulating spatial and temporal varying CO₂ signals from sources at the seafloor to help designing risk‐based monitoring programs