BASS measurements of currents, waves, stress, and turbulence in the North Sea bottom-boundary layer

1999 ◽  
Author(s):  
F.T. Thwaites ◽  
A.J. Williams
Keyword(s):  
Boundary Layer ◽  
North Sea ◽  
Bottom Boundary Layer ◽  
Bottom Boundary ◽  
The North ◽  
Sea Bottom ◽  
The North Sea

North Sea Bottom Boundary Layer Study for Pipelines

1987 ◽  
Author(s):  
H. Slaattelid ◽  
D. Myrhaugf ◽  
K.F. Lambroakos
Keyword(s):  
Boundary Layer ◽  
North Sea ◽  
Bottom Boundary Layer ◽  
Bottom Boundary ◽  
Sea Bottom

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

<p>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.</p><p>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.  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.</p>

scholarly journals Challenges in the Assessment of Bycatch: Postmortem Findings in Harbor Porpoises (Phocoena phocoena) Retrieved From Gillnets

2020 ◽  
pp. 030098582097245
Author(s):  
Lonneke L. IJsseldijk ◽  
Meike Scheidat ◽  
Marije L. Siemensma ◽  
Bram Couperus ◽  
Mardik F. Leopold ◽  
...  
Keyword(s):  
Health Status ◽  
North Sea ◽  
Electronic Monitoring ◽  
Nutritional Condition ◽  
Diagnostic Tools ◽  
Phocoena Phocoena ◽  
The North ◽  
Sea Bottom ◽  
The North Sea ◽  
Harbor Porpoises

Bycatch is considered one of the most significant threats affecting cetaceans worldwide. In the North Sea, bottom-set gillnets are a specific risk for harbor porpoises ( Phocoena phocoena). Methods to estimate bycatch rates include on-board observers, remote electronic monitoring, and fishermen voluntarily reporting; none of these are systematically conducted. Additionally, necropsies of stranded animals can provide insights into bycatch occurrence and health status of individuals. There are, however, uncertainties when it comes to the assessment of bycatch in stranded animals, mainly due to the lack of diagnostic tools specific for underwater entrapment. We conducted a literature review to establish criteria that aid in the assessment of bycatch in small cetaceans, and we tested which of these criteria applied to harbor porpoises retrieved from gillnets in the Netherlands ( n = 12). Twenty-five criteria were gathered from literature. Of these, “superficial incisions,” “encircling imprints,” and “recent ingestion of prey” were observed in the vast majority of our confirmed bycatch cases. Criteria like “pulmonary edema,” “pulmonary emphysema,” and “organ congestion” were also frequently observed, although considered unspecific as an indicator of bycatch. Notably, previously mentioned criteria as “favorable health status,” “absence of disease,” or “good nutritional condition” did not apply to the majority of our bycaught porpoises. This may reflect an overall reduced fitness of harbor porpoises inhabiting the southern North Sea or a higher chance of a debilitated porpoise being bycaught, and could result in an underestimation of bycatch rates when assessing stranded animals.

A bifacial tool of the Neanderthals from Ameland, the Netherlands

2013 ◽  
Vol 92 (2-3) ◽  
pp. 181-192 ◽  
Author(s):  
D. Stapert ◽  
L. Johansen ◽  
M.J.L.Th. Niekus
Keyword(s):  
The Netherlands ◽  
North Sea ◽  
Surface Modifications ◽  
Middle Palaeolithic ◽  
The North ◽  
Sea Bottom ◽  
The North Sea

AbstractA bifacially worked flint tool has recently been found on the North Sea beach of Ameland, one of the Wadden Islands in the northern Netherlands. It probably dates from the Middle Palaeolithic because its surface modifications include windgloss which in this area originated especially during the Weichselian Late Pleniglacial. The tool was probably first worked by a skilled knapper and subsequently, after a break occurred, by an apprentice. It is suggested that the tool was transported to Ameland from the North Sea bottom in the course of sand replenishment activities. Other artefacts from the Wadden Islands allegedly left by Neanderthals are also briefly discussed.

Impact of a sea breeze on the boundary-layer dynamics and the atmospheric stratification in a coastal area of the North Sea

2007 ◽  
Vol 125 (1) ◽  
pp. 133-154 ◽  
Author(s):  
Charles Talbot ◽  
Patrick Augustin ◽  
Céline Leroy ◽  
Véronique Willart ◽  
Hervé Delbarre ◽  
...  
Keyword(s):  
Boundary Layer ◽  
North Sea ◽  
Coastal Area ◽  
Sea Breeze ◽  
The North ◽  
Atmospheric Stratification ◽  
The North Sea ◽  
Boundary Layer Dynamics
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