Coast Of Denmark Research Articles

Long‐distance migrations, population mixing, and growth rate of lumpfish (Cyclopterus lumpus) revealed from tag‐recaptures

AbstractWe reveal that lumpfish (Cyclopterus lumpus) frequently migrate over long distances between their summer feeding area in the open ocean and their spring spawning sites in coastal areas, through applying tag‐recapture methodology. A total of 2750 C. lumpus were tagged in the Irminger Sea around Iceland and in the Norwegian Sea over 6 years, of which 17 C. lumpus were recaptured. Interestingly, four individuals were recaptured more than 1000 km distant from where they were tagged. C. lumpus tagged in the Irminger Sea and north of Iceland were recaptured around Iceland, whereas none of the fish tagged in other areas of the Norwegian Sea were recaptured in Iceland. This difference in recapture rate from different areas suggests that a higher proportion of C. lumpus from the Irminger Sea and north of Iceland spawns around Iceland in comparison with C. lumpus in other areas. Two fish tagged east of Iceland were recaptured on the coast of Denmark, with one fish having a displacement distance of 1612 km. The recapture of these two fish in Denmark demonstrates that part of the C. lumpus population spawning in Denmark utilizes the Norwegian Sea as a major feeding area and that the Norwegian Sea is a common feeding area for several distinct populations of C. lumpus. The growth rate of tagged fish varied from 1.2 to 11.1 cm year−1, indicating that males that are >20 cm and females that are >25 cm during the summer are capable of sufficient growth to achieve a suitable size for spawning (≥25 and ≥35 cm for males and females, respectively) the following spring.

Enhanced offshore wind resource assessment using hybrid data fusion and numerical models

Wind resource assessments are crucial for pre-construction planning of wind farms, especially offshore. This study proposes a novel hybrid model integrating Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN) and Empirical Wavelet Transform (EWT) for enhanced wind speed forecasting. This secondary decomposition reduces forecasting complexity by processing high-frequency signals. A Bidirectional Long Short-Term Memory (BiLSTM) neural network optimized with the Grey Wolf Optimizer (GWO) is then employed for forecasting. The model’s accuracy is evaluated using simulated wind speeds along the coast of Denmark, combined with lidar measurements through data fusion. This approach demonstrates significant improvements in prediction accuracy, highlighting its potential for offshore wind resource assessment.

Offshore wind resource assessment based on scarce spatio-temporal measurements using matrix factorization

In the pre-construction of wind farms, wind resource assessment is of paramount importance. Measurements by lidars are a source of high-fidelity data. However, they are expensive and sparse in space and time. Contrarily, Weather Research and Forecasting models generate continuous data with relatively low fidelity. We propose a hybrid approach combining measurements and output from numerical simulations for the assessment of offshore wind. Firstly, the datasets were fed onto a matrix, with columns representing the spatial lidar and WRF points, and the rows representing the time steps. Entries of the matrix reflect the wind speed, empty entries represent unobserved data. Then, matrix factorization using Gaussian process was employed for filling the missing entries with statistically calculated estimates. The model was optimized with stochastic gradient descent to apply GP without approximation methods. To evaluate the method, wind speed data along the coast of Denmark were used. The proposed technique, evaluated using two experiments, resulted in 58% more accurate results than the industrial standard method with trivial increase of computational cost. The RMSE of the proposed method ranges between 0.35 and 0.52 m/s.

Simulation of Density and Flow Dynamics in a Lagoon Aquifer Environment and Implications for Nutrient Delivery From Land to Sea

The near coastal zone, hosting the saltwater-freshwater interface, is an important zone that nutrients from terrestrial freshwaters have to pass to reach marine environments. This zone functions as a highly reactive biogeochemical reactor, for which nutrient cycling and budget is controlled by the water circulation within and across that interface. This study addresses the seasonal variation in water circulation, salinity pattern and the temporal seawater-freshwater exchange dynamics at the saltwater-wedge. This is achieved by linking geophysical exploration and numerical modeling to hydrochemical and hydraulic head observations from a lagoon site at the west coast of Denmark. The hydrochemical data from earlier studies suggests that increased inland recharge during winter drives a saltwater-wedge regression (seaward movement) whereas low recharge during summer causes a wedge transgression. Transient variable density model simulations reproduce only the hydraulic head dynamics in response to recharge dynamics, while the salinity distribution across the saltwater wedge cannot be reproduced with accuracy. A dynamic wedge is only simulated in the shallow part of the aquifer (<5 m), while the deeper parts are rather unaffected by fluctuations in freshwater inputs. Fluctuating salinity concentrations in the lagoon cause the development of a temporary intertidal salinity cell. This leads to a reversed density pattern in the underlying aquifer and the development of a freshwater containing discharge tube, which is confined by an overlying and underlying zone of saltwater. This process can explain observed trends in the in-situ data, despite an offset in absolute concentrations. Geophysical data indicates the presence of a deeper low hydraulic conductive unit, which coincides with the stagnant parts of the simulated saltwater-wedge. Thus, exchange fluxes refreshing the deeper low permeable areas are reduced. Consequently, this study suggests a very significant seasonal water circulation within the coastal aquifer near the seawater-freshwater interface, which is governed by the hydrogeological setting and the incoming freshwater fluxes, where nutrient delivery is limited to a small corridor of the shallow part of the aquifer.

Discovery of the first pincer wasp (Hymenoptera, Dryinidae) from Rovno amber.

Dryinidae (Hymenoptera: Chrysidoidea) are recorded for the first time from Rovno amber (Ukraine), following the discovery of one female of Dryinus janzeni Olmi. Holotypes of D. balticus (Olmi) and D. bruesi (Olmi) previously assigned to the Baltic amber, were actually collected on the coast of Denmark, so that they have to be recorded as specimens in Scandinavian (Danish) amber. As a result, true records of Dryinus species of group 3 (Olmi 1993) in Baltic amber are three: D. janzeni, D. bruesi, because of a second specimen found in true Baltic amber, and D. velteni Olmi. Dryinidae are the 33th hymenopteran family known from Rovno amber. Three species, D. janzeni, D. bruesi and D. balticus are known from understudied Rovno and Scandinavian amberoriginated from the warmer south coast of the Subparathetys. Dryinus janzeni is the 115th hymenopteran species known from Rovno amber and the first Dryinus record from Ukraine.

What’s New in Adaptive Management and Restoration of Coasts and Estuaries?

Adaptive learning about nature, based on observations and continual rethinking, dates back to Native Americans in what we call Traditional Ecological Knowledge. Fast forward to 1950+, when Eugene, Howard, and William Odum promoted sound science and its use in managing ecosystems—called adaptive management (AM). What began as an instinctive way of thinking and deciding how to obtain resources using accumulated information became a structured, science-based process that improves over time, given continual critiques of projects, clarification of definitions, and analyses of outcomes. The basic need is still to sustain ecosystem services despite uncertainties, such as climate change. I report recent innovations in the AM of estuaries and coasts that can add knowledge and improve future efforts. Innovations include new guidelines and approaches to confront uncertainty, engage stakeholders, improve governance, prioritize actions, centralize the role of science, and manage holistically. AM has been effective along the coast of Denmark and in several estuaries, and it is evolving elsewhere. In The Netherlands, Spain, California, and Oregon, large field experiments are generating “learning while restoring” (adaptive restoration, AR). AM and AR can help managers of coastal ecosystems and watersheds mitigate the impacts of rising sea levels, sea storms, and human disturbances. Science-based decision-making will become more nimble and protection/restoration more effective as innovations and model approaches are tailored to individual estuaries and coasts.

Accessibility assessment for operation and maintenance of offshore wind farms in the North Sea

AbstractFocused on offshore wind energy operation and maintenance applications, this work presents a detailed accessibility analysis of the North Sea. After a review of existing normative dedicated to inspection and access of offshore wind turbines, a rigorous mathematical formulation of relevant accessibility parameters is given by means of the set theory. Long‐term and high‐resolution metocean data are extracted from reanalysis databases and used to evaluate spatial and temporal variability of such parameters. Respectively restricted by significant wave height and mean wind speed, access by workboat and helicopter is evaluated. Being affected by both wave height and wind speed. Access by offshore crane is also analyzed. It resulted that the UK coast and the southern region of the North Sea are highly accessible, while the coast of Denmark and Norway undergoes more severe metocean conditions. This is, however, balanced by a higher wind resource. Moreover, a strong seasonality is ascertained, together with a drastic reduction of accessibility during daytime in a vast part of the basin. Accessibility during daytime in winter and autumn is very difficult for the whole North Sea. Among the studied farms, Dogger Bank is by far the one with the highest resource and lowest accessibility, while Thorntonbank III the one with the lowest resource and highest accessibility. In addition, accessibility is non‐linearly related to wind speed and wave height limits chosen for the access strategies covered. Copyright © 2016 John Wiley & Sons, Ltd.

Passive Filter Design and Offshore Wind Turbine Modelling for System Level Harmonic Studies

This paper is aimed at creating a framework for harmonic studies of an offshore wind power plant by means of system level time domain simulations. Many modern wind turbine generators employ full-scale power electronic converters, thus the filter connected between the power electronic converter and grid becomes a key aspect. The main contribution of the paper is a comparison between eight LCL-filter configurations. The 400 MW Anholt offshore wind power plant off the coast of Denmark, and its 3.6 MW turbines, is considered a reference for this paper.LCL filters find broad application in the grid integration of power electronic converters. Common practices for the tuning of such filters are therefore examined and adapted to the requirements of a specific test case. Hence, a set of parameters is defined for the LCL filter of a grid connected 3.6 MW wind turbine with a full-scale power electronic converter. LCL filters are further examined through analysis in the frequency domain, focusing on passive damping methods and variations of the capacitive branch which may improve the characteristics of such filters. Finally, a time-domain model of a grid-connected wind turbine inverter is established. Eight different LCL-filter configurations are implemented and compared in terms of harmonic content and losses. It is shown how dedicated additional branches are able to reduce both losses and harmonic content. This analysis is carried out using open-loop converter control system. A simple model including the full control system is constructed and outlined in a separate section.

The power of cooperation

The power of cooperation

Comment on Jonathan Benjamin's ‘Submerged Prehistoric Landscapes and Underwater Site Discovery: Reevaluating the ‘Danish Model’ for International Practice’

Jonathan Benjamin (2010) offers a well-reasoned and tested procedure to maximize the discovery of prehistoric underwater sites, building on the work of Fischer along the coast of Denmark, and then ...

Molecular identification of European flounder (Platichthys flesus) and its hybrids with European plaice (Pleuronectes platessa)

AbstractKijewska, A., Burzyński, A., and Wenne, R. 2009. Molecular identification of European flounder (Platichthys flesus) and its hybrids with European plaice (Pleuronectes platessa). – ICES Journal of Marine Science, 66: 902–906. European flounder (Platichthys flesus) and plaice (Pleuronectes platessa) are commercially important marine fish species inhabiting the continental shelf waters of Europe. Morphological similarity between the two makes it difficult to identify their hybrids, so species misclassification can generate errors in defining stocks in terms of their conservation and management. Flounder and plaice populations from the North Sea and the Baltic Sea were studied. Mitochondrial DNA (mtDNA) was used to confirm the morphological species identification. The set of molecular markers, two mitochondrial (cytochrome b and D-loop) and two nuclear (the ribosomal marker ITS and parathyroid hormone-related protein gene), was constructed to identify the two flatfish species and their hybrids. “Pure” flounder (P. flesus) were observed in the Bay of Gdańsk, Baltic Sea, and off the coast of Denmark in the North Sea. The fishing area near Bornholm in the Baltic is rich in P. flesus × P. platessa hybrids. The length difference of the amplified D-loop fragment was used for species identification. The characteristics of heteroplasmy in the control region (D-loop) can be useful as a population marker in the European flounder. Our studies demonstrate the utility of mtDNA polymorphism combined with nuclear molecular markers for correct identification of the morphologically similar and hybridized European flounder and plaice.

The impact of freshwater discharges on the ocean circulation in the Skagerrak/northern North Sea area. Part II: energy analysis

We perform eddy-permitting to eddy-resolving simulations of the Skagerrak/northern North Sea with a terrain-following numerical ocean model. We demonstrate that realistic representations of freshwater input are not required when the focus is on modelling mesoscale structures such as meanders and eddies. To arrive at this conclusion, we analyze the results using a recently developed energy diagnostic scheme to study the sensitivity to realistic representations of the lateral freshwater flux provided to the area from the Baltic Sea and by the major rivers. The scheme is suitable for analysis of growth of instabilities, and it has four basic instability processes prominent. We recognize both horizontal and vertical shear instabilities. There are two processes where average potential energy is converted to eddy kinetic energy, and they are related to the mean gradient in surface elevation and the mean lateral density gradient, respectively. The latter process is known as frontal instability. We demonstrate that the change in the eddy kinetic energy field is small, despite the large variations in the hydrographic properties from experiment to experiment. Moreover, generation of eddy activity appears at the same locations and with approximately the same strength regardless of actual representations of freshwater input. Furthermore, we find that vertical shear instability dominates the energy conversion processes in the Norwegian Coastal Current. Finally, we find that the areas off the northwest coast of Denmark recognized with enhanced eddy kinetic energy level is not caused by instability processes but eddy–eddy interaction rooted in variations in the sea level.

Fra fritidsfornøjelse til markedsføring - Esbjerg Kommune og idrætten

From leisure enjoyment to marketing – Esbjerg municipal and sport.The city of Esbjerg was founded in 1873 as an extension of the establishment of the first export harbour on the west coast of Denmark. Between 1870 and 1901 the town’s population rose from about 500 to 13,300, and this explosive growth meant that all financial resources had to be devoted to building housing, roads and public institutions, not least schools for the newcomers’ many children. Esbjerg then grew throughout the 1900s into a modern city, which today has 82,000 inhabitants. The founding of the city coincided in time with the establishment of sport in Denmark, and the city’s first sports associations emerged between 1885 and 1900. After the First World War these associations grew both in number and in the range of clubs that were available for most known branches of sport. The Municipal’s attitude to sport can briefly be broken down into four phases: The first phase up until about 1918-19 was marked by the fact that all the Municipal’s energies were devoted to establishing an urban society, and that therefore if there was any support at all for sporting facilities it was only modest. The second phase from about 1920 to 1950 was characterised by collaboration between the Municipal and the amalgamation known as Esbjerg Idrætforbund (Esbjerg Sports Union). The first stadium was built in 1929 and during the following ten years sporting facilities were extended. The third phase from the end of the 1950s to about 1970 is a period marked by expansion with construction extending to new residential areas. At the same time the Sports Union became the Municipal’s partner in the administration of new laws on public support for youth and sports initiatives. The fourth and final phase to date made itself felt in the 1980s and 90s, when elite sport grew up alongside broader sporting practice. The Municipal continues its collaboration with the Sports Union, but now takes independent initiatives together with the elite clubs as a way to market Esbjerg as a modern city, setting up international prestige projects, for example, such as hosting the Youth Olympics in 1999.

Sediment distribution and transport in the shallow coastal waters along the west coast of Denmark

Until recently, studies of the regional distribution of seabed sediments off the littoral zone of the Danish North Sea coast had been concentrated on the Jutland Bank area (Fig. 1; Leth 1996, 1998). Knowledge on the sedimentary conditions and processes along the entire west coast of Jutland has, however, significantly increased as a result of 2000 km of newly acquired high-resolution seismic and side-scan sonar data, supplemented by about 100 vibrocores. These data were collected by the Geological Survey of Denmark and Greenland (GEUS) during joint projects with the Danish Coastal Authority between 1998 and 2001 (Leth et al. 1999; Larsen & Leth 2001). The coastal zone off west Jutland displays a highly dynamic environment, where sediment transport is governed by strong tidal and wave-induced currents. The net wave-generated current is south going, while the coastal current has a net direction towards the north (Knudsen et al. 2002). The direction of the net littoral drift is southward from the outlet of Limfjorden to Blåvands Huk, with net erosion north of Nymindegab and aggregation to the south; the offshore part of this depositional system has recently been studied (Larsen & Leth 2001).

Large Scale Offshore Wind Energy in the North Sea — A Technology and Policy Perspective

With the ground breaking 160 megawatt wind farm Horns Rev, off the coast of Denmark in the North Sea, installed and operating, offshore wind energy experts are progressing with optimism. With a portfolio for offshore wind farms in north-western Europe that foresees in an accumulated installed power of more than 3 gigawatt by the end of 2006, the future indeed looks bright. But will the expectations for offshore wind energy be met? Based on experience from technical and market-orientated studies on offshore wind energy (OWE), the Energy research Centre of the Netherlands ECN concludes that the growth of OWE in the next few years will mainly be hampered by insufficient policy support, rather than by technical barriers. The realisation of the first two Dutch offshore wind farms has been delayed considerably. Towards the end of 2004, the Dutch policy will shift to a concession system for the issuing of exclusive rights for plots in the North Sea. For the tendered sites surrounding the UK coast, the financial returns appear marginal. Moreover, according to market models, the incentives for offshore wind energy in Germany are insufficient for successful competition with other electricity supplies in the liberalised European market. The main technical challenges are the increase of turbine availability by improvement of turbine operation and maintenance (O&M) and a further reduction of wind farm array losses by innovation in turbine operation and farm layout. Focusing on The Netherlands, a significant upgrade of the grid is required to feed-in the Dutch goal of 6000 megawatt in 2020 successfully.

Sea surface drag coefficients in the Risø Air Sea Experiment

This study examines the dependence of the computed drag coefficient on wind speed, stability, fetch, flux sampling problems, and method of calculation of the drag coefficient. The analysis is applied to data collected at a tower 2 km off the coast of Denmark during the Risø Air Sea Experiment (RASEX). Various flux sampling problems are evaluated to eliminate unreliable fluxes. Large drag coefficients are observed with weak large‐scale flow. However, the value of the computed drag coefficient at weak wind speeds is sensitive to flux sampling problems and the method of calculation of the drag coefficient, which might be a general characteristic of weak winds. The drag coefficient is significantly larger for short fetch conditions, particularly at strong wind speeds.

Pathways of organic carbon oxidation in three continental margin sediments

We have combined several different methodologies to quantify rates of organic carbon mineralization by the various electron acceptors in sediments from the coast of Denmark and Norway. Rates of NH + 4 and ∑CO 2 liberation in sediment incubations were used with O 2 penetration depths to conclude that O 2 respiration accounted for only between 3.6–17.4% of the total organic carbon oxidation. Dentrification was limited to a narrow zone just below the depth of O 2 penetration, and was not a major carbon oxidation pathway. The processes of Fe reduction, Mn reduction and sulfate reduction dominated organic carbon mineralization, but their relative significance varied depending on the sediment. Where high concentrations of Mnoxide were found (3–4 wt% Mn), only Mn reduction occurred. With lower Mn oxide concentrations more typical of coastal sediments, Fe reduction and sulfate reduction were most important and of a similar magnitude. Overall, most of the measured O 2 flux into the sediment was used to oxidized reduced inorganic species and not organic carbon. We suspect that the importance of O 2 respiration in many coastal sediments has been overestimated, whereas metal oxide reduction (both Fe and Mn reduction) has probably been well underestimated.

Eastern and Western Influences on Performer Training at Eugenio Barba's Odin Teatret

The Odin Teatret, which continues to produce new and exciting works, was originally formed in Oslo, Norway, in 1964. In 1966 the company moved to Holstebro, a small town near the west coast of Denmark, where it has been based ever since. In its 23-year history the company has mounted productions ranging from intimate studio pieces, for audiences as small as sixty or less, to huge street spectacles encapsulating whole villages at a time. The Odin has traveled extensively in Europe, South America, and Asia. It has established a major theatre center in Holstebro, where it publishes books, makes and rents films, and mounts workshops in collaboration with artists such as Jerzy Grotowski, Dario Fo, and JeanLouis Barrault; and it is the only state-supported pedagogical institute devoted to theatre research in Western Europe. Barba, the founder and artistic director of the Odin, began his theatre career as an assistant to Grotowski in the early sixties, long before Grotowski became known in the West. In fact, Barba was instrumental in introducing Grotowski to the world by organizing the Theatre Laboratory's first European tour, and through books and articles, including Towards a Poor Theatre, which Barba edited, and the famous Tulane Drama Review articles of 1965, written by Barba and Ludwig Flaszen, which were among the first materials published on Grotowski in the United States. Barba, unlike Grotowski, has remained in the theatre and is rec-

Ultrastructural observations on some marine choanoflagellates from the coast of Denmark

The external morphology of eight species of choanoflagellates representing seven genera has been investigated with the electron microscope. Descriptions of three new species (Pleurasiga cupula, Diaphanoeca pedicellata and Stephanoeca pedicellata), a new variety (Pleurasiga minima var. minuta) and an emended description of Salpingoeca natans Gr⊘ntved are provided. All species possess a characteristic protoplast with a single anterior flagellum surrounded by a collar of tentacles and all possess a lorica composed of costae. In two species (Acanthoeca brevipoda Ellis and Diplotheca costata Valkanov) the costal strips forming the posterior chamber are broader than usual. Sections of two species show the presence of a very thin and delicate membrane which secures the protoplast to the lorica.

The Netherlands-Denmark submerged-repeater system

The paper describes the equipment used to provide 36 telephone channels on each of two submarine cables laid between Oostmahorn in the Netherlands and the island of Romo on the west coast of Denmark, a distance of some 142 nautical miles. Details are given of the construction and performance of the submerged repeaters used, together with the special terminal equipment associated with them.