Sensitivity analysis of dissipation parameterizations in the WAVEWATCH III spectral wave model using the ST6 source term packages for Ireland Coast.

2020 ◽  
Author(s):  
Leandro Fernández ◽  
Clement Calvino ◽  
Frederic Dias
Keyword(s):  
Sensitivity Analysis ◽  
North Atlantic ◽  
Source Term ◽  
Wave Model ◽  
Long Distance ◽  
Wavewatch Iii ◽  
North East ◽  
The North ◽  
Spectral Wave Model ◽  
The North Atlantic

<p>The research we perform has important engineering applications since a lot of marine activities and offshore engineering activities are in shallow water areas where phenomena like bottom and white-capping dissipation and wind growth take place. The physical parametrization of such forcing/dissipation has become an important issue in the improvement of the performance of models in order to provide accurate sea-state information. In this regard, we perform a sensitivity analysis of dissipation parameterizations in the third-generation spectral wave model WAVEWATCH III using the ST6 source term packages, proposed by Zieger-Babanin 2015, to describe wind generation and dissipation due to white-capping and bottom friction.</p><p>A system of nested grids is used to model long distance swells generated in the North Atlantic Ocean and propagating all the way to the west coast of Ireland. We used a 30-minute coarse resolution for the North Atlantic grid, a 6-minute intermediate resolution for the North-East Atlantic, and a 3-minute fine resolution in coastal areas closer to Ireland.</p><p>The sensitivity analysis in the parameterization is based on the effect of the model performance by varying the adjustable parameters in the wind input source, swell dissipation in terms of the interaction of waves with oceanic turbulence and the drag coefficient to potentially eliminate a bias in the wind field. The results of the model for the coast of Ireland are discussed in terms of various parametrization schemes.</p>

Edges and interactions beyond Europe

2018 ◽  
Author(s):  
Peter S. Wells ◽  
Naoise Mac Sweeney
Keyword(s):  
North America ◽  
Iron Age ◽  
North Atlantic ◽  
Cultural Practices ◽  
Raw Materials ◽  
Long Distance ◽  
The North ◽  
First Millennium ◽  
Temperate Europe ◽  
The North Atlantic

Iron Age Europe, once studied as a relatively closed, coherent continent, is being seen increasingly as a dynamic part of the much larger, interconnected world. Interactions, direct and indirect, with communities in Asia, Africa, and, by the end of the first millennium AD, North America, had significant effects on the peoples of Iron Age Europe. In the Near East and Egypt, and much later in the North Atlantic, the interactions can be linked directly to historically documented peoples and their rulers, while in temperate Europe the evidence is exclusively archaeological until the very end of the prehistoric Iron Age. The evidence attests to often long-distance interactions and their effects in regard to the movement of peoples, and the introduction into Europe of raw materials, crafted objects, styles, motifs, and cultural practices, as well as the ideas that accompanied them.

A new species of amphipod, Megamphopus katagani sp. nov. (Crustacea: Peracarida: Photidae) from the Sea of Marmara (Turkey), with a key to the species of Megamphopus in the North Atlantic, Mediterranean and associated Seas

Zootaxa ◽  
2011 ◽  
Vol 2791 (1) ◽  
pp. 63 ◽  
Author(s):  
KEREM BAKIR ◽  
MURAT SEZGIN ◽  
ALAN A. MYERS
Keyword(s):  
New Species ◽  
North Atlantic ◽  
Sea Of Marmara ◽  
East Atlantic ◽  
North East ◽  
The North ◽  
The North Atlantic ◽  
A New Species

A new species of amphipod, Megamphopus katagani sp. nov., is described from the sea of Marmara (Turkey). A key to the species of Megamphopus known from the North-East Atlantic, Mediterranean and associated seas is provided.

scholarly journals Water mass distributions and transports for the 2014 GEOVIDE cruise in the North Atlantic

2018 ◽  
Vol 15 (7) ◽  
pp. 2075-2090 ◽  
Author(s):  
Maribel I. García-Ibáñez ◽  
Fiz F. Pérez ◽  
Pascale Lherminier ◽  
Patricia Zunino ◽  
Herlé Mercier ◽  
...  
Keyword(s):  
North Atlantic ◽  
Water Mass ◽  
Water Levels ◽  
Water Masses ◽  
Meridional Overturning Circulation ◽  
Labrador Sea ◽  
Intermediate Water ◽  
North East ◽  
The North ◽  
The North Atlantic

Abstract. We present the distribution of water masses along the GEOTRACES-GA01 section during the GEOVIDE cruise, which crossed the subpolar North Atlantic Ocean and the Labrador Sea in the summer of 2014. The water mass structure resulting from an extended optimum multiparameter (eOMP) analysis provides the framework for interpreting the observed distributions of trace elements and their isotopes. Central Waters and Subpolar Mode Waters (SPMW) dominated the upper part of the GEOTRACES-GA01 section. At intermediate depths, the dominant water mass was Labrador Sea Water, while the deep parts of the section were filled by Iceland–Scotland Overflow Water (ISOW) and North-East Atlantic Deep Water. We also evaluate the water mass volume transports across the 2014 OVIDE line (Portugal to Greenland section) by combining the water mass fractions resulting from the eOMP analysis with the absolute geostrophic velocity field estimated through a box inverse model. This allowed us to assess the relative contribution of each water mass to the transport across the section. Finally, we discuss the changes in the distribution and transport of water masses between the 2014 OVIDE line and the 2002–2010 mean state. At the upper and intermediate water levels, colder end-members of the water masses replaced the warmer ones in 2014 with respect to 2002–2010, in agreement with the long-term cooling of the North Atlantic Subpolar Gyre that started in the mid-2000s. Below 2000 dbar, ISOW increased its contribution in 2014 with respect to 2002–2010, with the increase being consistent with other estimates of ISOW transports along 58–59° N. We also observed an increase in SPMW in the East Greenland Irminger Current in 2014 with respect to 2002–2010, which supports the recent deep convection events in the Irminger Sea. From the assessment of the relative water mass contribution to the Atlantic Meridional Overturning Circulation (AMOC) across the OVIDE line, we conclude that the larger AMOC intensity in 2014 compared to the 2002–2010 mean was related to both the increase in the northward transport of Central Waters in the AMOC upper limb and to the increase in the southward flow of Irminger Basin SPMW and ISOW in the AMOC lower limb.

Modelling Wave-Current-Turbulence Interactions for Tidal Energy Applications

2020 ◽  
Author(s):  
Vengatesan Venugopal ◽  
Arne Vögler
Keyword(s):  
North Atlantic ◽  
Tidal Current ◽  
Current Model ◽  
Coupled Model ◽  
Wave Model ◽  
Tidal Energy ◽  
The North ◽  
Wave Parameters ◽  
The North Atlantic ◽  
Coupled Wave

Abstract This paper presents the nature of turbulence parameters produced from 3-dimensional numerical simulations using an ocean scale wave-tidal current model applied to tidal energy sites in the Orkney waters in the United Kingdom. The MIKE 21/3 coupled wave-current model is chosen for this study. The numerical modelling study is conducted in two stages. First, a North Atlantic Ocean large-scale wave model is employed to simulate wave parameters. Spatial and temporal wind speeds extracted from the European Centre for Medium Range Weather Forecast (ECMWF) is utilised to drive the North Atlantic wave model. Secondly, the wave parameters produced from the North Atlantic model are used as boundary conditions to run a coupled wave-tidal current model. A turbulence model representing the turbulence and eddy viscosity within the coupled model is chosen and the turbulence kinetic energy (TKE) due to wave-current interactions are computed. The coupled model is calibrated with Acoustic Doppler and Current Profiler (ADCP) measurements deployed close to a tidal energy site in the Inner Sound of the Pentland Firth. The model output parameters such as the current speed, TKE, horizontal and vertical eddy viscosities, significant wave height, peak wave period and wave directions are presented, and, their characteristics are discussed in detail.

Ophlitaspongia and Ophlitaspongia papilla reinstated, and a new species of Ophlitaspongia described (Porifera: Demospongiae: Microcionidae)

1999 ◽  
Vol 79 (4) ◽  
pp. 609-620 ◽  
Author(s):  
C.M. Howson ◽  
S.J. Chambers
Keyword(s):  
New Species ◽  
North Atlantic ◽  
Deep Water ◽  
The Other ◽  
East Atlantic ◽  
Halichondria Panicea ◽  
North East ◽  
The North ◽  
The North Atlantic ◽  
A New Species

A new species of Ophlitaspongia (Porifera: Microcionidae) from wave-exposed sublittoral rock in the north-east Atlantic is described and compared to the two other species recorded from the genus in the north-east Atlantic. The species known as Ophlitaspongia seriata is considered to be a junior synonym of Halichondria panicea. Consequently, the name O. papilla has been reinstated. The other recorded species O. basifixa, is from deep water. Ophlitaspongia basifixa has characters which differentiate it from Ophlitaspongia sp. nov. The genus Ophlitaspongia has been separated from related genera and reinstated for species in the North Atlantic.

An Operational System for Predicting Hurricane-Generated Wind Waves in the North Atlantic Ocean*

2005 ◽  
Vol 20 (4) ◽  
pp. 652-671 ◽  
Author(s):  
Yung Y. Chao ◽  
Jose-Henrique G. M. Alves ◽  
Hendrik L. Tolman
Keyword(s):  
Prediction Model ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Wind Waves ◽  
Wave Model ◽  
Atlantic Hurricane ◽  
The North ◽  
Hurricane Season ◽  
The North Atlantic ◽  
Environmental Prediction

Abstract A new wind–wave prediction model, referred to as the North Atlantic hurricane (NAH) wave model, has been developed at the National Centers for Environmental Prediction (NCEP) to produce forecasts of hurricane-generated waves during the Atlantic hurricane season. A detailed description of this model and a comparison of its performance against the operational western North Atlantic (WNA) wave model during Hurricanes Isidore and Lili, in 2002, are presented. The NAH and WNA models are identical in their physics and numerics. The NAH model uses a wind field obtained by blending data from NCEP’s operational Global Forecast System (GFS) with those from a higher-resolution hurricane prediction model, whereas the WNA wave model uses winds provided exclusively by the GFS. Relative biases of the order of 10% in the prediction of maximum wave heights up to 48 h in advance, indicate that the use of higher-resolution winds in the NAH model provides a successful framework for predicting extreme sea states generated by a hurricane. Consequently, the NAH model has been made operational at NCEP for use during the Atlantic hurricane season.

Projected Changes in the Occurrence of Extreme and Rogue Waves in Future Climate in the North Atlantic

2017 ◽  
Author(s):  
Odin Gramstad ◽  
Elzbieta Bitner-Gregersen ◽  
Erik Vanem
Keyword(s):  
North Atlantic ◽  
Wave Spectrum ◽  
Wave Model ◽  
Rogue Waves ◽  
Wave Climate ◽  
Future Climate ◽  
The North ◽  
Wave Parameters ◽  
The Future ◽  
The North Atlantic

We investigate the future wave climate in the North Atlantic with respect to extreme events as well as on wave parameters that have previously not been considered in much details in the perspective of wave climate change, such as those associated with occurrence of rogue waves. A number of future wave projections is obtained by running the third generation wave model WAM with wind input derived from several global circulation models. In each case the wave model has been run for the 30-year historical period 1971–2000 and the future period 2071–2100 assuming the two different future climate scenarios RCP 4.5 and RCP 8.5. The wave model runs have been carried out by the Norwegian Meteorological Institute in Bergen, and the climate model result are taken from The Coupled Model Intercomparison Project phase 5 - CMIP5. In addition to the standard wave parameters such as significant wave height and peak period the wave model runs provided the full two-dimensional wave spectrum. This has enabled the study of a larger set of wave parameters. The focus of the present study is the projected future changes in occurrence of extreme sea states and extreme and rogue waves. The investigations are limited to parameters related to this in a few selected locations in the North Atlantic. Our results show that there are large uncertainties in many of the parameters considered in this study, and in many cases the different climate models and different model scenarios provide contradicting results with respect to the predicted change from past to future climate. There are, however, some situations for which a clearer tendency is observed.

scholarly journals The <sup>226</sup>Ra-Ba relationship in the North Atlantic during GEOTRACES-GA01

2017 ◽  
Author(s):  
Emilie Le Roy ◽  
Virginie Sanial ◽  
Matthew A. Charette ◽  
Pieter van Beek ◽  
François Lacan ◽  
...  
Keyword(s):  
North Atlantic ◽  
Thermohaline Circulation ◽  
Water Mass ◽  
Continental Margins ◽  
Strongly Correlated ◽  
North East ◽  
The North ◽  
Deep Waters ◽  
Similar Chemical ◽  
The North Atlantic

Abstract. We report detailed sections of radium-226 (226Ra, T1/2 = 1602 y) activities and barium (Ba) concentrations determined in the North Atlantic (Portugal-Greenland-Canada) in the framework of the international GEOTRACES program (GA01 section – GEOVIDE project, May–July 2014). Dissolved 226Ra and Ba are strongly correlated along the GA01 section, a pattern that reflects their similar chemical behavior. Since 226Ra and Ba have been widely used as tracers of water masses and ocean mixing, we investigated more thoroughly their behavior in this crucial region for thermohaline circulation taking advantage of the contrasting biogeochemical patterns existing along the GA01 section. We used an Optimum Multiparameter (OMP) analysis to distinguish the relative importance of physical transport (water mass mixing) from non-conservative processes (sedimentary, river, or hydrothermal inputs; uptake by particles, and dissolved-particulate dynamics) on the 226Ra and Ba distributions in the North Atlantic. Results show that 72 % of the 226Ra and 68 % of the Ba can be explained by conservative mixing along the section and therefore, they can be considered as conservative tracers of water mass transport in the ocean interior. However, regions where 226Ra and Ba displayed non-conservative behavior were also identified, mostly at the ocean boundaries (seafloor, continental margins, and surface waters). Elevated 226Ra and Ba concentrations found in deep waters of the West European Basin reflect that lower North East Atlantic Deep Water (NEADWl) accumulates excess 226Ra and Ba from sediment diffusion during transport. In the upper 1500 m, deficiencies in 226Ra and Ba are likely explained by their incorporation in planktonic siliceous shells, or in barite (BaSO4) (Bishop, 1988). Finally, since Ba and 226Ra display different source terms (mostly deep-sea sediments for 226Ra and rivers for Ba), strong decoupling between 226Ra and Ba were observed at the land-ocean boundaries. This is especially true in the shallow stations near the coasts of Greenland and Newfoundland where high 226Ra / Ba ratios at depth reflect the diffusion of 226Ra from sediment and low 226Ra / Ba ratios in the upper water column reflect the input of Ba associated with meteoric waters.

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