Validation of a three-dimensional biophysical model using nutrient observations in the North Sea

Abstract Aggregations of site-attached populations can show marked differences in density due to variation in local productivity and mortality processes. Matching management actions to the scale of biological processes is therefore important for sustainable fisheries management. This study examined the adequacy and appropriate scale of a spatially explicit management regime for sandeel, Ammodytes marinus, in the North Sea. Information from biophysical model simulations of larval transport and otolith chemistry was used to estimate the scale of mixing among aggregations. Together, these approaches indicated that there was negligible exchange of pre-settled sandeel among aggregations >200 km apart. Additionally, a re-analysis of tag-recapture experiments and distribution data indicated that the dispersive range decreased further after settlement. Significant differences in length at maturity and year-class strength not only reflect the limited mixing across the North Sea, but also point to regional differences in productivity and thereby vulnerability to fishing pressure. We conclude that the current management regime comprised of multiple assessment areas enable these differences to be considered in advice on annual fishing quotas.

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A Methodology for DP Capability Studies on Remotely Operated Vehicles

Volume 7A: Ocean Engineering ◽

10.1115/omae2017-61918 ◽

2017 ◽

Author(s):

Juan A. Ramírez-Macías ◽

Rafael E. Vásquez ◽

Asgeir J. Sørensen ◽

Svein Sævik

Keyword(s):

North Sea ◽

Three Dimensional ◽

Dynamic Positioning ◽

Remotely Operated Vehicles ◽

Environmental Loads ◽

The North ◽

Surface Vessels ◽

The North Sea ◽

Position And Orientation ◽

Surface Vessel

Dynamic Positioning (DP) capability studies are used to assess if a vessel has sufficient thrust capacity to withstand environmental loads while keeping its position and orientation at a specified set-point or path. These studies are usually performed on ships and other DP-controlled surface vessels; consequently, standards and procedures for these are widely known. In this work, a methodology for conducting a DP capability study for Remotely Operated Vehicles (ROV) is presented. Due to the nature of ROV operations, a DP capability study should include different features that are not common to surface vessels. In this case, an ROV connected to a surface vessel through a tether is considered. During operation, the tether is subject to varying current loads that are accumulated along the water column and transferred to the vehicle. Therefore, the ROVs thrusters must be able to withstand, in addition to its own drag, three-dimensional loads due to three-dimensional currents and umbilical-related loads. To illustrate the methodology, two case studies are considered: the DP capability of an ROV that has to operate in the Colombian Caribbean and an existing ROV operating in the North Sea.

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

Ocean Science Discussions ◽

10.5194/osd-10-1765-2013 ◽

2013 ◽

Vol 10 (5) ◽

pp. 1765-1806 ◽

Cited By ~ 1

Author(s):

M. C. H. Tiessen ◽

L. Fernard ◽

T. Gerkema ◽

J. van der Molen ◽

P. Ruardij ◽

...

Keyword(s):

North Sea ◽

Sea Water ◽

A Priori ◽

Three Dimensional ◽

Larval Transport ◽

Absolute Amount ◽

Annual Variability ◽

The North ◽

The North Sea ◽

Selection Of

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 was made. The aim was to investigate to what extent variability in the hydrodynamic conditions alone (reflecting passive particle transport) contributed to inter-annual variability in transport of eggs and larvae. In this idealized study, no a-priori selection of spawning grounds or periods was made and no active behaviour (vertical migration) or mortality were included. 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 coastal areas, as well as in the relative importance of the different areas. Settlement in the western Dutch Wadden Sea not only showed inter-annual variability, but patterns were also variable within each year and revealed seasonal changes in the origin of particles.

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ROLE OF 2D AND 3D MODELS IN JONSDAP '76

Coastal Engineering Proceedings ◽

10.9753/icce.v16.63 ◽

1978 ◽

Vol 1 (16) ◽

pp. 63

Author(s):

A.M. Davies

Keyword(s):

North Sea ◽

Three Dimensional ◽

3D Models ◽

Three Dimensional Model ◽

North West ◽

The North ◽

Dimensional Distribution ◽

The North Sea ◽

2D And 3D

This paper describes how a two-dimensional numerical model of the North Sea was used to determine optimum positions for the deployment of off-shore tide gauges during the JONSDAP '76 oceanographic exercise. A three-dimensional model of the North West European Shelf is also described. Using this model the three-dimensional distribution of the M2 tidal current over the shelf has been computed. This model has also been used to compute the wind induced circulation of the North Sea for the INOUT period of JONSDAP '76.

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