Secondary circulation in shallow ocean straits: Observations and numerical modeling of the Danish Straits

2020 ◽  
Author(s):  
Verena Haid ◽  
Emil Stanev ◽  
Johannes Pein ◽  
Joanna Staneva ◽  
Wei Chen
Keyword(s):  
Large Scale ◽  
Unstructured Grid ◽  
Secondary Circulation ◽  
Atmospheric Variability ◽  
Tidal Straining ◽  
The North ◽  
The North Sea ◽  
Similarities And Differences ◽  
Transport And Mixing ◽  
Resolution Simulation

<p>We study the secondary circulation in the Danish Straits using the unstructured-grid hydrodynamic model SCHISM covering the North Sea and Baltic Sea. The resolution in the straits is up to ~100 m. Since the large-scale atmospheric variability controls the transport in these straits, we focus on the processes with subtidal time scales. We compare the in- and outflows in the straits to flood and ebb flows in estuaries and analyze similarities and differences. Very prominently, the outflow and inflow phases of the Danish Straits feature substantial differences to the tidal straining in estuaries. With a resolution of ~100 m, new transport and mixing pathways, previously unresolved, appear fundamental to the strait dynamics. The variability of the strait bathymetry leads to a strongly differing appearance of secondary circulation. Helical cells, often with a horizontal extension of ~1 km, develop in the deep parts of the channels. A comparison between the high-resolution simulation and a simulation with a coarser grid of ~500 m in the straits suggests that the coarser resolution overestimates the stratification and misrepresents the transport balance. Axial velocities and transport through the Sound are underestimated by ~12%. These differences are explained by the underdeveloped secondary circulation in the coarse-resolution simulation and the associated changes in mixing along the straits. In conclusion, the use of ultrafine resolution grids is essential to adequately resolve secondary flow patterns and two-layer exchange.</p>

Offshore Claims and Problems in the North Sea

1965 ◽  
Vol 59 (3) ◽  
pp. 505-522 ◽  
Author(s):  
Richard Young
Keyword(s):  
North Sea ◽  
Large Scale ◽  
Geneva Convention ◽  
Legal Principles ◽  
The North ◽  
Legal Problems ◽  
The North Sea ◽  
The Subject ◽  
First Time ◽  
Economic Considerations

The possible presence of very large petroleum and natural gas reserves in the area beneath the North Sea is currently the subject of intense investigation. If confirmed, as seems likely in at least some localities, this occurrence will raise legal problems of considerable interest and complexity. For the North Sea is not merely an oilfield covered by water: for centuries it has been one of the world's major fishery regions and the avenue to and from the world's busiest seaports. Thus all three of the present principal uses of the sea—fishing, navigation, and the exploitation of submarine resources—promise to meet for the first time on a large scale in an area where all are of major importance. The process of reconciling the various interests at stake will provide the first thoroughgoing test of the adequacy and acceptability of the general principles laid down in the 1958 Geneva Convention on the Continental Shelf and should add greatly to the practice and precedents available in this developing branch of the law. In the present article an attempt is made to review some of the geographical and economic considerations involved in the North Sea situation, to note some of the technical and legal developments that have already taken place, and to consider these elements in the light of the various interests and legal principles concerned.

scholarly journals Inferring the location and scale of mixing between habitat areas of lesser sandeel through information from the fishery

2010 ◽  
Vol 68 (1) ◽  
pp. 43-51 ◽  
Author(s):  
Henrik Jensen ◽  
Anna Rindorf ◽  
Peter J. Wright ◽  
Henrik Mosegaard
Keyword(s):  
North Sea ◽  
Large Scale ◽  
Pelagic Fish ◽  
Fishing Ground ◽  
Marine Science ◽  
Foraging Habitat ◽  
Small Pelagic Fish ◽  
The North ◽  
The North Sea

Abstract Jensen, H., Rindorf, A., Wright, P. J., and Mosegaard, H. 2011. Inferring the location and scale of mixing between habitat areas of lesser sandeel through information from the fishery. – ICES Journal of Marine Science, 68: 43–51. Sandeels are small pelagic fish that play an important role in the diet of a range of natural predators. Because of their limited capture by traditional survey gear, little is known about their large-scale distribution or the degree of mixing between habitat areas. Detailed information collected directly from the fishery was used to map fishing grounds, which were then assumed to reflect the foraging habitat of the species. Length distributions from individual hauls were used to assess differences in the distributions as a function of distance between samples. Sandeel foraging habitat covered some 5% of the total area of the North Sea. Mixing between neighbouring fishing grounds was too low to eliminate differences in length distributions at distances between grounds down to 5 km. Within fishing grounds, mixing was sufficient to eliminate differences in length distributions at scales <28 km but insufficient at greater distances. The lack of mixing between grounds may result in large differences in sandeel abundance among adjacent fishing grounds. Further, notable abundance at one end of an extensive fishing ground is not necessarily indicative of similar abundance at its other end.

Large-scale assessment of masking potential by underwater ship noise the North Sea

2021 ◽  
Vol 150 (4) ◽  
pp. A80-A81
Author(s):  
Jakob Tougaard ◽  
Thomas Folegot ◽  
Christ de Jong ◽  
Emily T. Griffiths ◽  
Alexander M. von Benda-Beckmann ◽  
...  
Keyword(s):  
North Sea ◽  
Large Scale ◽  
Large Scale Assessment ◽  
The North ◽  
Scale Assessment ◽  
The North Sea

Study of sand wave migration over five years as observed in two windfarm development areas, and the implications for building on moving substrates in the North Sea

2014 ◽  
Vol 105 (4) ◽  
pp. 241-249 ◽  
Author(s):  
Ken P. Games ◽  
David I. Gordon
Keyword(s):  
Case Studies ◽  
Large Scale ◽  
Oil And Gas ◽  
Sand Wave ◽  
Sand Waves ◽  
Migration Rates ◽  
The North ◽  
The North Sea ◽  
Wave Migration ◽  
The Impact

ABSTRACTSand waves are well known indicators of a mobile seabed. What do we expect of these features in terms of migration rates and seabed scour? We discuss these effects on seabed structures, both for the Oil and Gas and the Windfarm Industries, and consider how these impact on turbines and buried cables. Two case studies are presented. The first concerns a windfarm with a five-year gap between the planning survey and a subsequent cable route and environmental assessment survey. This revealed large-scale movements of sand waves, with the displacement of an isolated feature of 155 m in five years. Secondly, another windfarm development involved a re-survey, again over a five-year period, but after the turbines had been installed. This showed movements of sand waves of ∼50 m in five years. Observations of the scour effects on the turbines are discussed. Both sites revealed the presence of barchans. Whilst these have been extensively studied on land, there are few examples of how they behave in the marine environment. The two case studies presented show that mass transport is potentially much greater than expected and that this has implications for choosing turbine locations, the effect of scour, and the impact these sediment movements are likely to have on power cables.

scholarly journals Day-ahead Market Modelling of Large-scale Highly-renewable Multi-energy Systems: Analysis of the North Sea Region Towards 2050

2020 ◽  
Author(s):  
Juan Gea Bermúdez ◽  
Kaushik Das ◽  
Hardi Koduvere ◽  
Matti Juhani Koivisto
Keyword(s):  
North Sea ◽  
Large Scale ◽  
Unit Commitment ◽  
District Heating ◽  
Energy Systems ◽  
Energy System ◽  
Computational Time ◽  
Integer Variables ◽  
The North ◽  
The North Sea

This paper proposes a mathematical model to simulate Day-ahead markets of large-scale multi-energy systems with high share of renewable energy. Furthermore, it analyses the importance of including unit commitment when performing such analysis. The results of the case study, which is performed for the North Sea region, show the influence of massive renewable penetration in the energy sector and increasing electrification of the district heating sector towards 2050, and how this impacts the role of other energy sources such as thermal and hydro. The penetration of wind and solar is likely to challenge the need for balancing in the system as well as the profitability of thermal units. The degree of influence of the unit commitment approach is found to be dependent on the configuration of the energy system. Overall, including unit commitment constraints with integer variables leads to more realistic behaviour of the units, at the cost of increasing considerably the computational time. Relaxing integer variables reduces significantly the computational time, without highly compromising the accuracy of the results. The proposed model, together with the insights from the study case, can be specially useful for system operators for optimal operational planning.

scholarly journals Large-Scale Flow and the Long-Lasting Blocking High over Russia: Summer 2010

2012 ◽  
Vol 140 (9) ◽  
pp. 2967-2981 ◽  
Author(s):  
Andrea Schneidereit ◽  
Silke Schubert ◽  
Pavel Vargin ◽  
Frank Lunkeit ◽  
Xiuhua Zhu ◽  
...  
Keyword(s):  
Heat Wave ◽  
Large Scale ◽  
Wave Structure ◽  
Arctic Region ◽  
Stationary Wave ◽  
Boreal Summer ◽  
Atmospheric Variability ◽  
The North ◽  
Blocking High ◽  
Large Scale Flow

Abstract Several studies show that the anomalous long-lasting Russian heat wave during the summer of 2010, linked to a long-persistent blocking high, appears mainly as a result of natural atmospheric variability. This study analyzes the large-scale flow structure based on the ECMWF Re-Analysis Interim (ERA-Interim) data (1989–2010). The anomalous long-lasting blocking high over western Russia including the heat wave occurs as an overlay of a set of anticyclonic contributions on different time scales. (i) A regime change in ENSO toward La Niña modulates the quasi-stationary wave structure in the boreal summer hemisphere supporting the eastern European blocking. The polar Arctic dipole mode is enhanced and shows a projection on the mean blocking high. (ii) Together with the quasi-stationary wave anomaly, the transient eddies maintain the long-lasting blocking. (iii) Three different pathways of wave action are identified on the intermediate time scale (~10–60 days). One pathway commences over the eastern North Pacific and includes the polar Arctic region; another one runs more southward and crossing the North Atlantic, continues to eastern Europe; a third pathway southeast of the blocking high describes the downstream development over South Asia.

Large-scale siliciclastic input during the Paleocene-Eocene Thermal Maximum in the North Sea Basin

2021 ◽  
Author(s):  
Simin Jin ◽  
David Kemp ◽  
David Jolley ◽  
Manuel Vieira ◽  
Chunju Huang
Keyword(s):  
Carbon Isotope ◽  
North Sea ◽  
Climate Warming ◽  
Large Scale ◽  
Time Lag ◽  
Sediment Supply ◽  
Deep Time ◽  
The North ◽  
Thermal Maximum ◽  
The North Sea

&lt;p&gt;The Paleocene-Eocene Thermal Maximum (PETM, ~56 Ma) was the most marked climate warming event of the Cenozoic, and a potentially useful deep time analogue for understanding environmental responses to anthropogenic carbon emissions and associated warming. The response of sedimentary systems to the large-scale climate changes of the PETM are, however, still uncertain. Here, we present an extremely thick (~140 m) record of the PETM in cores from a well in the North Sea, offshore UK. In this well, a thick Paleocene-Eocene interval is developed owing to uplift of the East Shetland Platform in the late Paleocene. Carbon isotope data through this well, coupled with detailed sedimentological analysis, show that the PETM interval is contemporaneous with &gt;200 sandstone turbidites layers. Mud deposition without turbidites dominated sedimentation below and above the PETM. These observations support previous work from other localities highlighting how climate warming during the PETM likely drove substantial changes in hydrological cycling, erosion and sediment supply. Spectral analysis of turbidite recurrence in the PETM interval suggests that the abundance of turbidites was modulated in part by ~21 kyr astronomical precession climate cycles, further emphasizing a potential climatic control on turbidite sedimentation. In detail, we note a kiloyear-scale time lag between onset of the PETM carbon isotope excursion and the appearance of turbidites in the succession, highlighting a delay between PETM carbon release and warming and the basin-wide response in sediment supply.&lt;/p&gt;

scholarly journals Zebrafish-Based Discovery of Antiseizure Compounds from the North Sea: Isoquinoline Alkaloids TMC-120A and TMC-120B

Marine Drugs ◽  
2019 ◽  
Vol 17 (11) ◽  
pp. 607 ◽  
Author(s):  
Daniëlle Copmans ◽  
Sara Kildgaard ◽  
Silas A. Rasmussen ◽  
Monika Ślęzak ◽  
Nina Dirkx ◽  
...  
Keyword(s):  
Large Scale ◽  
Brain Activity ◽  
Isoquinoline Alkaloids ◽  
Seizure Duration ◽  
Larval Zebrafish ◽  
The North ◽  
Structural Analogues ◽  
The North Sea ◽  
Large Scale Screening ◽  
The Eu

There is a high need for the development of new and improved antiseizure drugs (ASDs) to treat epilepsy. Despite the potential of marine natural products (MNPs), the EU marine biodiscovery consortium PharmaSea has made the only effort to date to perform ASD discovery based on large-scale screening of MNPs. To this end, the embryonic zebrafish photomotor response assay and the larval zebrafish pentylenetetrazole (PTZ) model were used to screen MNP extracts for neuroactivity and antiseizure activity, respectively. Here we report the identification of the two known isoquinoline alkaloids TMC-120A and TMC-120B as novel antiseizure compounds, which were isolated by bioactivity-guided purification from the marine-derived fungus Aspergillus insuetus. TMC-120A and TMC-120B were observed to significantly lower PTZ-induced seizures and epileptiform brain activity in the larval zebrafish PTZ seizure model. In addition, their structural analogues TMC-120C, penicisochroman G, and ustusorane B were isolated and also significantly lowered PTZ-induced seizures. Finally, TMC-120A and TMC-120B were investigated in a mouse model of drug-resistant focal seizures. Compound treatment significantly shortened the seizure duration, thereby confirming their antiseizure activity. These data underscore the possibility to translate findings in zebrafish to mice in the field of epilepsy and the potential of the marine environment for ASD discovery.

scholarly journals Need for Caution in Interpreting Extreme Weather Statistics

2015 ◽  
Vol 28 (23) ◽  
pp. 9166-9187 ◽  
Author(s):  
Prashant D. Sardeshmukh ◽  
Gilbert P. Compo ◽  
Cécile Penland
Keyword(s):  
Process Model ◽  
Large Scale ◽  
Probability Distributions ◽  
Extreme Weather ◽  
Recent Change ◽  
Atmospheric Variability ◽  
Tail Probabilities ◽  
The North ◽  
Special Cases ◽  
Non Gaussian

Abstract Given the reality of anthropogenic global warming, it is tempting to seek an anthropogenic component in any recent change in the statistics of extreme weather. This paper cautions that such efforts may, however, lead to wrong conclusions if the distinctively skewed and heavy-tailed aspects of the probability distributions of daily weather anomalies are ignored or misrepresented. Departures of several standard deviations from the mean, although rare, are far more common in such a distinctively non-Gaussian world than they are in a Gaussian world. This further complicates the problem of detecting changes in tail probabilities from historical records of limited length and accuracy. A possible solution is to exploit the fact that the salient non-Gaussian features of the observed distributions are captured by so-called stochastically generated skewed (SGS) distributions that include Gaussian distributions as special cases. SGS distributions are associated with damped linear Markov processes perturbed by asymmetric stochastic noise and as such represent the simplest physically based prototypes of the observed distributions. The tails of SGS distributions can also be directly linked to generalized extreme value (GEV) and generalized Pareto (GP) distributions. The Markov process model can be used to provide rigorous confidence intervals and to investigate temporal persistence statistics. The procedure is illustrated for assessing changes in the observed distributions of daily wintertime indices of large-scale atmospheric variability in the North Atlantic and North Pacific sectors over the period 1872–2011. No significant changes in these indices are found from the first to the second half of the period.

Wind wake effects of large offshore wind farms, an underrated impact on the marine ecosystem?

2020 ◽  
Author(s):  
Corinna Schrum ◽  
Naveed Akhtar ◽  
Nils Christiansen ◽  
Jeff Carpenter ◽  
Ute Daewel ◽  
...  
Keyword(s):  
Boundary Layer ◽  
North Sea ◽  
Large Scale ◽  
Spatial Scales ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Farms ◽  
The North ◽  
The North Sea ◽  
Ocean Hydrodynamics

&lt;p&gt;The North Sea is a world-wide hot-spot in offshore wind energy production and installed capacity is rapidly increasing. Current and potential future developments raise concerns about the implications for the environment and ecosystem. Offshore wind farms change the physical environment across scales in various ways, which have the potential to modify biogeochemical fluxes and ecosystem structure. The foundations of wind farms cause oceanic wakes and sediment fluxes into the water column. Oceanic wakes have spatial scales of about O(1km) and structure local ecosystems within and in the vicinity of wind farms. Spatially larger effects can be expected from wind deficits and atmospheric boundary layer turbulence arising from wind farms. Wind disturbances extend often over muliple tenths of kilometer and are detectable as large scale wind wakes. Moreover, boundary layer disturbances have the potential to change the local weather conditions and foster e.g. local cloud development. The atmospheric changes in turn changes ocean circulation and turbulence on the same large spatial scales and modulate ocean nutrient fluxes. The latter directly influences biological productivity and food web structure. These cascading effects from atmosphere to ocean hydrodynamics, biogeochemistry and foodwebs are likely underrated while assessing potential and risks of offshore wind.&lt;/p&gt;&lt;p&gt;We present latest evidence for local to regional environmental impacts, with a focus on wind wakes and discuss results from observations, remote sensing and modelling.&amp;#160; Using a suite of coupled atmosphere, ocean hydrodynamic and biogeochemistry models, we quantify the impact of large-scale offshore wind farms in the North Sea. The local and regional meteorological effects are studied using the regional climate model COSMO-CLM and the coupled ocean hydrodynamics-ecosystem model ECOSMO is used to study the consequent effects on ocean hydrodynamics and ocean productivity. Both models operate at a horizontal resolution of 2km.&lt;/p&gt;

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