scholarly journals Reconstructing North Sea palaeolandscapes from 3D and high-density 2D seismic data: An overview

2014 ◽  
Vol 93 (1-2) ◽  
pp. 31-42 ◽  
Author(s):  
S. van Heteren ◽  
J.A.C. Meekes ◽  
M.A.J. Bakker ◽  
V. Gaffney ◽  
S. Fitch ◽  
...  
Keyword(s):  
North Sea ◽  
Spatial Scales ◽  
Building Blocks ◽  
High Density ◽  
Glacial Cycles ◽  
The North ◽  
3D Data ◽  
Hunting And Gathering ◽  
Environmental Setting ◽  
The North Sea

AbstractThe North Sea subsurface shows the marks of long-term tectonic subsidence. Much of it contains a thick record of glacial and interglacial deposits and landscapes, formed during multiple glacial cycles and the associated regressions and transgressions during the past two million years. At times of lower sea level than today, areas that are presently submerged were fertile lowlands more favourable for hunting and gathering than the surrounding upland. These drowned lowlands are not captured by traditional 1:250,000 geological maps of the North Sea subsurface because the underlying seismic and core data are commonly too widely spaced to achieve this. Palaeolandscape mapping requires identification of building blocks with spatial scales in the order of 1 km or less. As high-density 2D and high-quality 3D seismics are becoming available for an increasing part of the North Sea, glacial and interglacial palaeolandscapes can be reconstructed for more and more areas. An overview of published palaeolandscape reconstructions shows that shallow time slices through 3D data provide map views that are very suitable for the identification of landscape elements. For optimal results, each time slice needs to be validated and ground-truthed with 2D seismics and with descriptions and analyses of cores and borehole samples. Interpretations should be made by teams of geoscientists with a sufficiently broad range of expertise to recognise and classify even subtle or unfamiliar patterns and features. The resulting reconstructions will provide a context and an environmental setting for Palaeolithic, Mesolithic, and Neolithic societies and finds.

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 Interannual variability in the summer dissolved organic matter inventory of the North Sea: implications for the continental shelf pump

2019 ◽  
Vol 16 (5) ◽  
pp. 1073-1096 ◽  
Author(s):  
Saisiri Chaichana ◽  
Tim Jickells ◽  
Martin Johnson
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Continental Shelf ◽  
North Sea ◽  
North Atlantic ◽  
Spatial Scales ◽  
General Pattern ◽  
C:N Ratio ◽  
The North ◽  
The North Sea

Abstract. We present the distribution and C:N stoichiometry of dissolved organic matter (DOM) in the North Sea in two summers (August 2011 and August 2012), with supporting data from the intervening winter (January 2012). These data demonstrate local variability superimposed on a general pattern of decreasing DOM with increasing distance from land, suggesting concentrations of DOM are controlled on large spatial scales by mixing between the open North Atlantic and either riverine sources or high DOM productivity in nearshore coastal waters driven by riverine nutrient discharge. Given the large size and long residence time of water in the North Sea, we find concentrations are commonly modified from simple conservative mixing between two endmembers. We observe differences in dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) concentrations and land–ocean gradients between the two summers, leading to an estimated 10–20 Tg difference in the DOC inventory between the two years, which is of the same order of magnitude as the annual uptake of atmospheric CO2 by the North Sea system, and thus significant for the carbon budget of the North Sea. This difference is not consistent with additional terrestrial loading and is more likely to be due to balancing of mixing and in situ production and loss processes across the North Sea. Differences were particularly pronounced in the bottom layer of the seasonally stratifying northern North Sea, with higher DOC and C:N ratio in 2011 than in 2012. Using other data, we consider the extent to which these differences in the concentrations and C:N ratio of DOM could be due to changes in the biogeochemistry or physical circulation in the two years, or a combination of both. The evidence we have is consistent with a flushing event in winter 2011/12 exchanging DOM-rich, high C:N shelf waters, which may have accumulated over more than 1 year, with deep North Atlantic waters with lower DOC and marginally higher DON. We discuss the implications of these observations for the shelf sea carbon pump and the export of carbon-rich organic matter off the shelf and hypothesise that intermittent flushing of temperate shelf systems may be a key mechanism in the maintenance of the continental shelf pump, via the accumulation and subsequent export of carbon-rich DOM.

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