A brief analysis of North Sea physics

Sündermann, Jürgen; Pohlmann, Thomas

doi:10.5697/oc.53-3.663

Cited by 106 publications

(94 citation statements)

References 8 publications

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“…The particles drifted in an anticlockwise fashion, especially in the central North Sea. This conformed with the typical circulation pattern (Otto et al, 1990;Sündermann and Pohlmann, 2011). Just south-west of Dover Straight and along the eastern shores, particles showed the largest drift Figure 5.…”

Section: Particle Drift and Settlement Successsupporting

confidence: 81%

Numerical modelling of physical processes governing larval transport in the southern North Sea

et al. 2014

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Abstract.A three-dimensional hydrodynamic model (GETM) was coupled with a particle tracking routine (GITM) to study the inter-annual variability in transport paths of particles in the North Sea and English Channel. For validation, a comparison with observed drifter trajectories is also presented here. This research investigated to what extent variability in the hydrodynamic conditions alone (reflecting passive particle transport) contributed to interannual variability in the transport of eggs and larvae. In this idealised study, no a priori selection of specific spawning grounds or periods was made and no active behaviour (vertical migration) or mortality was included. In this study, egg and larval development towards coastal nursery areas was based solely on sea water temperature, while settlement areas were defined by a threshold water depth. Results showed strong inter-annual variability in drift direction and distance, caused by a combination of wind speed and direction. Strong inter-annual variability was observed both in absolute amount of settlement in several coastal areas, and in the relative importance of the different areas. The effects of wind and temperature variability are minor for settlement along the western shores of the North Sea and in the English Channel, but have a very significant impact on settlement along the eastern shores of the North Sea. Years with strong south-westerly winds across the Dover Straight resulted in higher settlement figures along its eastern shores of the North Sea (standard deviation 37 % of the mean annual settlement value). Settlement in the western Dutch Wadden Sea did not only show inter-annual variability, but patterns were also variable within each year and revealed seasonal changes in the origin of particles: during winter, stronger currents along with colder temperatures generally result in particles originating from further away.

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Section: Particle Drift and Settlement Successsupporting

confidence: 81%

Numerical modelling of physical processes governing larval transport in the southern North Sea

et al. 2014

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“…The wind-driven residual circulation in the North Sea is significantly influenced by the North Atlantic Oscillation (NAO). This can be seen in Figure 21, which shows results from a model calculation by Sündermann and Pohlmann (2011) indicating that the currents under a NAO+ situation are much stronger than during a negative one. Moreover, currents in the central northern part of the basin, where site 22/4b is located, are directed eastward under NAO+ conditions and northwestward under NAOconditions, which obviously influences the spreading of (passive) tracers, such as methane (strictly speaking, the dissolution of methane causes a slight reduction in seawater density (O'Sullivan and Smith, 1970;Schmid et al, 2004), which however can be neglected due to the small solubility of methane in seawater (Gupta, 2010;Linke et al, 2010).…”

Section: Climate Variabilitymentioning

confidence: 86%

A review of oceanographic and meteorological controls on the North Sea circulation and hydrodynamics with a view to the fate of North Sea methane from well site 22/4b and other seabed sources

Nauw

Haas

Rehder

2015

Marine and Petroleum Geology

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The North Sea hydrodynamics are key to the redistribution of methane released at site 22/4b, located at (57 o 55'N, 1 o 38'E) in the UK Central North Sea, 200 km east of the Scottish mainland. This review summarizes the current state of knowledge on the North Sea circulation, stratification and variability therein and briefly discusses the potential consequences for the distribution and fate of methane released from site 22/4b or other seabed sources. Astronomical tidal waves follow an anti-clockwise path and tide-topography interaction generates a residual circulation in the same direction. Wind stress forcing can enhance, reduce or even reverse this circulation. Variations in the strength of the Fair Isle Current (FIC) are important. The FIC enters the North Sea between The Orkneys and Shetland, follows approximately the 100-m isobath, passes along site 22/4b, and ends up in the Norwegian Trench. The North Atlantic Oscillation (NAO) also causes variability. A positive (negative) NAO index is associated with stronger (weaker) than normal westerly winds. NAO+ situations strengthen the circulation in the North Sea, whereas it weakens during NAOconditions and is directed northeastward. High positive correlations exist between the SST at site 22/4b and the NAO index. Climate change can have a long-term effect on the hydrodynamics of the North Sea. Seasonal stratification has potentially the most important imprint on methane derived from well site 22/4b. Summertime heating stratifies the northern part of the North Sea. In autumn, loss of heat to the atmosphere causes the stratification to break down until tides and storms mix the entire water column. During the period of stratification, the bulk of (dissolved) methane released from site 22/4b gets trapped below the thermocline. The loss of methane to the atmosphere thus becomes a function of the relative time scales of transport and horizontal and vertical mixing processes versus the time scale of microbial degradation (oxidation) in the water column.

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“…The link between the NAO and Atlantic inflow would likely be stronger if the wind-driven flow were included. While the NAO is thought to affect inflows to the North Sea via water mass exchange, this is secondary to the control that it exerts on the wind-driven circulation (Sündermann and Pohlmann, 2011). Marsh et al (2017) hypothesise a strong link between Atlantic inflow into the North Sea and the salinity of the North Sea on interannual timescales.…”

Section: Interannual Variabilitymentioning

confidence: 99%

Thermohaline forcing and interannual variability of northwestern inflows into the northern North Sea

Sheehan

Berx

Gallego

et al. 2017

Continental Shelf Research

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A brief analysis of North Sea physics

Cited by 106 publications

References 8 publications

Numerical modelling of physical processes governing larval transport in the southern North Sea

Numerical modelling of physical processes governing larval transport in the southern North Sea

A review of oceanographic and meteorological controls on the North Sea circulation and hydrodynamics with a view to the fate of North Sea methane from well site 22/4b and other seabed sources

Thermohaline forcing and interannual variability of northwestern inflows into the northern North Sea

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