scholarly journals Spatio-temporal variability of tidal-stream energy in north-western Europe

2020 ◽  
Vol 378 (2178) ◽  
pp. 20190493 ◽  
Author(s):  
Nicolas Guillou ◽  
Simon P. Neill ◽  
Jérôme Thiébot
Keyword(s):  
Temporal Variability ◽  
Western Europe ◽  
Energy Resource ◽  
Phase Relationship ◽  
Tidal Energy ◽  
The North ◽  
Tidal Stream ◽  
Tidal Stream Energy ◽  
Spatio Temporal ◽  
North Western

Initial selection of tidal stream energy sites is primarily based on identifying areas with the maximum current speeds. However, optimal design and deployment of turbines requires detailed investigations of the temporal variability of the available resource, focusing on areas with reduced variability, and hence the potential for more continuous energy supply. These aspects are investigated here for some of the most promising sites for tidal array development across the north-western European shelf seas: the Alderney Race, the Fromveur Strait, the Pentland Firth and the channels of Orkney. Particular attention was dedicated to asymmetry between the flood and ebb phases of the tidal cycle (due to the phase relationship between M 2 and M 4 constituents), and spring-neap variability of the available resource (due to M 2 and S 2 compound tides). A series of high-resolution models were exploited to (i) produce a detailed harmonic database of these three components, and (ii) characterize, using energy resource metrics, temporal variability of the available power density. There was a clear contrast between the Alderney Race, with reduced temporal variability over semi-diurnal and fortnightly time scales, and sites in western Brittany and North Scotland which, due to increased variability, appeared less attractive for optimal energy conversion. This article is part of the theme issue ‘New insights on tidal dynamics and tidal energy harvesting in the Alderney Race’.

scholarly journals The Tidal Stream Energy Resource of the Fromveur Strait—A Review

2020 ◽  
Vol 8 (12) ◽  
pp. 1037
Author(s):  
Nicolas Guillou ◽  
Jean-Frédéric Charpentier ◽  
Mohamed Benbouzid
Keyword(s):  
Energy Resource ◽  
Tidal Energy ◽  
Energy Output ◽  
Wake Interactions ◽  
Tidal Stream ◽  
Technical Specifications ◽  
Tidal Stream Energy ◽  
Key Steps ◽  
A Site

Refined assessments of the available tidal stream energy resource are required to optimize turbines design and guarantee successful implementations and operations of devices in the marine environment. Investigations primary focused on identifying areas with maximum current speeds. However, further information may be reached by exhibiting (i) resource temporal variability, (ii) superimposed effects of meteo-oceanographic conditions (including especially wind-generated surface-gravity waves), and (iii) potential environmental impacts of operating turbines at the regional (e.g., changes in sediment transport and surrounding seabed features, effects on marine water quality, etc.) and local (wake-wake interactions and energy output) scales. These aspects are here investigated by reviewing a series of research studies dedicated to the Fromveur Strait off western Brittany, a region with strong potential for tidal array development along the coast of France. Particular attention is dedicated to the exploitation of combined in-situ and remote-sensing observations and numerical simulations. Beyond a site specific characterization of the tidal stream energy resource, this review promotes a series of original approaches and analysis methods for turbines optimization, thus complementing technical specifications to secure the key steps of a tidal energy project and promote the growth of a reliable tidal stream energy exploitation.

scholarly journals Simulation modelling of wind-induced sea level fluctuations at the ports of the Odesa Region in the North-Western part of the Black Sea

2019 ◽  
pp. 109-120
Author(s):  
Yu. S. Tuchkovenko
Keyword(s):  
Sea Level ◽  
Black Sea ◽  
Hydrodynamic Model ◽  
Temporal Variability ◽  
The Black Sea ◽  
Sea Level Fluctuations ◽  
The North ◽  
Allowable Error ◽  
Spatio Temporal ◽  
North Western

The paper is devoted to discussion of the prospects of simplified 2D hydrodynamic model use aimed at forecasting the wind-induced sea level fluctuations within the area of sea ports (Chornomorsk, Odesa and Yuzhnyi) of the Odesa Region in the North-Western part of the Black Sea. Spatio-temporal variability of wind conditions at the sea-atmosphere division is specified based on the data of the global numerical weather prediction model of the Global Forecast System (GFS). The research includes the description of the mathematical structure of the hydrodynamic model and the results of its adaptation to the conditions of the simulated sea area. It presents the results of model verification in the version which implies adoption of wind data from the archives of GFS-analysis and GFS-forecasts for 2010, 2016 and 2017. The verification was performed by comparing wind-induced denivellations of the sea level at the ports of Chornomorsk, Odesa and Yuzhnyi calculated over the course of modelling and those established on the basis of observational data (with the discreteness of 6 hours). A quantitative assessment of the calculation accuracy was performed for the cases where, according to the observational data, level denivellations exceeded the value of the standard deviation for the entire series. New series of the observed and calculated model-based significant wind-induced denivellations of sea level were formed for each of the ports from the sets of samples that met this condition. Using  these series estimates of the mean square error of the calculations, allowable error of calculations, correlation coefficient between the actual and calculated values of the level denivellations, the probability of the calculation method under the allowable error were obtained. It was established that in the case of use of the data from wind GFS-analysis (with spatial resolution of 0.5° both latitudinally and longitudinally) over the course of modelling the probability of calculation of significant sea level denivellation constitutes 84-85%, and in case of using the data from the GFS-archive of wind forecasts (with spatial resolution of 0.25°) – 88-91%. This allowed making a conclusion that the model has good prospects of use for operational forecast of the sea level fluctuations caused by storm wind in the version implying assimilation of the predicted information on the spatio-temporal variability of wind conditions obtained by means of the GFS global weather forecast model.

scholarly journals Independent components of spatial-temporal structure of chlorophyll a patterns in the upper layer of the north-western shelf of the Black Sea

One Ecosystem ◽  
2021 ◽  
Vol 6 ◽  
Author(s):  
Natalya Kyrylenko ◽  
Vladyslav Evstigneev
Keyword(s):  
Black Sea ◽  
Temporal Variability ◽  
Temporal Structure ◽  
The Black Sea ◽  
Phytoplankton Succession ◽  
Independent Components ◽  
The North ◽  
Component Decomposition ◽  
Spatio Temporal ◽  
North Western

In the present study, the results of independent component decomposition of satellite-derived chlorophyll a (Chla) patterns for the north-western part of the Black Sea are presented. The study has been carried out on the basis of the DINEOF-reconstructed dataset of 8-day average log-transformed Chla (alChla) patterns for 1997-2016. The alChla patterns were decomposed into six independent components of its spatio-temporal variability in the north-western shelf of the Black Sea. The independent components reflect the spatial distribution of alChla anomalies which are likely to be formed under the influence of sea circulation factors driven by wind. The paper presents the results of the analysis of the intra-annual variability of independent components. The interpretation of the patterns of intra-annual independent components variability is given, taking into account the seasonal variability of the wind factor, the flow of the Danube, the Dnieper and Southern Bug rivers and the fact of modulation of independent components dynamics by seasonal phytoplankton succession.

scholarly journals Striking forest revival at the end of the Roman Period in north-western Europe

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
C. Lambert ◽  
A. Penaud ◽  
M. Vidal ◽  
C. Gandini ◽  
L. Labeyrie ◽  
...  
Keyword(s):  
North Atlantic ◽  
Western Europe ◽  
Anthropogenic Activities ◽  
Sedimentary Environment ◽  
Pollen Grains ◽  
Roman Period ◽  
Freshwater Microalgae ◽  
Environmental Signals ◽  
The North ◽  
North Western

AbstractThe Holocene period (last 11,700 years BP) has been marked by significant climate variability over decadal to millennial timescales. The underlying mechanisms are still being debated, despite ocean–atmosphere–land connections put forward in many paleo-studies. Among the main drivers, involving a cluster of spectral signatures and shaping the climate of north-western Europe, are solar activity, the North Atlantic Oscillation (NAO) varying atmospheric regimes and North Atlantic oceanic gyre dynamics. Over the last 2500 years BP, paleo-environmental signals have been strongly affected by anthropogenic activities through deforestation and land use for crops, grazing, habitations, or access to resources. Palynological proxies (especially pollen grains and marine or freshwater microalgae) help to highlight such anthropogenic imprints over natural variability. Palynological analyses conducted in a macro-estuarine sedimentary environment of north-western France over the last 2500 years BP reveal a huge and atypical 300 year-long arboreal increase between 1700 and 1400 years BP (around 250 and 550 years AD) that we refer to as the ‘1.7–1.4 ka Arboreal Pollen rise event’ or ‘1.7–1.4 ka AP event’. Interestingly, the climatic 1700–1200 years BP interval coincides with evidence for the withdrawal of coastal societies in Brittany (NW France), in an unfavourable socio-economic context. We suggest that subpolar North Atlantic gyre strengthening and related increasing recurrence of storminess extremes may have affected long-term coastal anthropogenic trajectories resulting in a local collapse of coastal agrarian societies, partly forced by climatic degradation at the end of the Roman Period.

DISTRIBUTION OF TEMPERATURE INDICES OF EXTREME IN THE TERRITORY OF THE EUROPEAN PART OF RUSSIA IN THE PERIOD 1980-2019

2021 ◽  
Vol 31 (4) ◽  
pp. 437-442
Author(s):  
V.V. Guryanov ◽  
A.K. Sungatullin
Keyword(s):  
Temporal Variability ◽  
Statistical Processing ◽  
European Part ◽  
The North ◽  
Hourly Data ◽  
European Part Of Russia ◽  
Spatial Grid ◽  
Temperature Indices ◽  
Spatio Temporal ◽  
Maximum Temperatures

The spatio-temporal variability of the average values of temperature indices of climate extremity in the territory of the European part of Russia (ER) in 1980-2019 is presented. To calculate the extremeness indices, we used hourly data on the maximum and minimum temperatures obtained using the ERA5 reanalysis on a 1°´1° spatial grid. Statistical processing of the index values revealed an increase in the temperature indices TNX, TNN, TXN, TXX, associated with the minimum and maximum temperatures, with the exception of the north and southeast of the region. An increase in the number of sunny days and a decrease in the number of frosty days were also revealed.

scholarly journals Ships and their timber source as indicators of connections between regions

AmS-Skrifter ◽  
2020 ◽  
pp. 133-143
Author(s):  
Aoife Daly
Keyword(s):  
Western Europe ◽  
The Baltic Sea ◽  
The North ◽  
Baltic Coast ◽  
Art Objects ◽  
The North Sea ◽  
The Baltic ◽  
North And South ◽  
North Western

The precise dating and determination of the source of timbers in shipwrecks found around the coasts of the North Sea and the Baltic Sea, through dendrochronology allows us to see connections between north and  south, east and west throughout the region and to a high chronological precision. In this paper we take a look at results of recent analyses of timber from ships, and timber and barrel cargoes, to try to draw a chronological picture, from the twelfth to seventeenth centuries, of links between regions, through transport in oak ships and trade of timber. Archaeological finds of oak from timber cargos in shipwrecks and fine art objects (painted panels and sculpture) show the extent to which timber was shipped from Hanseatic towns along the southern Baltic coast, to western and north-western Europe.

Mapping Spatio-Temporal Variability in NAO Rainfall Signatures

2021 ◽  
Author(s):  
Harry West ◽  
Nevil Quinn ◽  
Michael Horswell
Keyword(s):  
Spatial Pattern ◽  
North Atlantic ◽  
Temporal Variability ◽  
Reliable Estimate ◽  
Jet Stream ◽  
Temporal Consistency ◽  
North West ◽  
The North ◽  
Cold Spots ◽  
Spatio Temporal

<p>The North Atlantic Oscillation (NAO) is often cited as the primary atmospheric-oceanic circulation or teleconnection influencing regional climate in Great Britain. As our ability to predict the NAO several months in advance improves, it is important that we also continue to develop our spatial and temporal understanding of the rainfall signatures which the circulation produces.</p><p>We present a novel application of spatial statistics to explore variability in monthly NAO rainfall signatures using a 5km gridded monthly Standardised Precipitation Index (SPI) dataset. We first use the Getis-Ord Gi* statistic to map spatially significant hot and cold spots (clusters of high/wet and low/dry SPI values) in average monthly rainfall signatures under NAO Positive and Negative conditions over the period 1900-2015. We then look across the record and explore the temporal variability in these signatures, in other words how often a location is in a significant spatial hot/cold spot (high/low SPI) at a monthly scale under NAO Positive/Negative conditions.</p><p>The two phases of the NAO are typically more distinctive in the winter months, with stronger and more variable NAO Index values. The average monthly SPI analysis reveals a north-west/south-east ‘spatial divide’ in rainfall response. NAO Positive phases result in a southerly North Atlantic Jet Stream bringing warm and wet conditions from the tropics, increasing rainfall particularly in the north-western regions. However, under NAO Negative phases which result in a northerly Jet Stream, much drier conditions in the north-west prevail. Meanwhile in the south-eastern regions under both NAO phases a weaker and opposite wet/dry signal is observed. This north-west/south-east ‘spatial divide’ is marked by the location of spatially extensive hot/cold spots. The Getis-Ord Gi* result identifies that the spatial pattern we detect in average winter rainfall is statistically significant. Looking across the record, this NW/SE opposing response appears to have a relatively high degree of spatio-temporal consistency. This suggests that there is a high probability that NAO Positive and Negative phases will result in this NW/SE statistically significant spatial pattern.</p><p>Even though the phases of the NAO in the summer months are less distinctive they still produce rainfall responses which are evident in the monthly average SPI. However, the spatiality in wet/dry conditions is more homogenous across the country. In other words the ‘spatial divide’ observed in winter is diluted in summer. As a result, the occurrence of significant hot/cold spots is more variable in space and time.</p><p>Our analysis demonstrates a novel application of the Getis-Ord Gi* statistic which allows for spatially significant patterns in the monthly SPI data to be mapped for each NAO phase. In winter months particularly, this analysis reveals statistically significant opposing rainfall responses, which appear to have long-term spatio-temporal consistency. This is important because as winter NAO forecasting skill improves, the findings of our research enable a more spatially reliable estimate of the likely impacts of NAO-influenced rainfall distribution.</p>

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