scholarly journals Climate-scale changes of the semidiurnal tide over the North Atlantic coasts from 1846 to 2018

2020 ◽  
Author(s):  
Lucia Pineau-Guillou ◽  
Pascal Lazure ◽  
Guy Wöppelmann
Keyword(s):  
North Atlantic ◽  
Large Scale ◽  
Low Frequency ◽  
Underlying Mechanism ◽  
East Atlantic ◽  
North West ◽  
North East ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

Abstract. We investigated the long-term changes of the principal tidal component M2 over the North Atlantic coasts, from 1846 to 2018. We analysed 9 tide gauges with time series starting no later than 1920. The longest is Brest with 165 years of observations. We carefully processed the data, particularly to remove the 18.6-year nodal modulation. We found that M2 variations are consistent at all the stations in the North East Atlantic (Newlyn, Brest, Cuxhaven), whereas some discrepancies appear in the North West Atlantic. The changes started long before the XXth century, and are not linear. The trends vary from a station to another; they are overall positive, up to 0.7 mm/yr. Since 1990, the trends switch from positive to negative values. Concerning the possible causes of the observed changes, the similarity between the North Atlantic Oscillation and M2 variations in the North East Atlantic suggests a possible influence of the large-scale atmospheric circulation on the tide. We discuss a possible underlying mechanism. A different spatial distribution of water heights from one year to another, depending on the low-frequency sea-level pressure patterns, could impact the propagation of the tide in the North Atlantic basin. However, the hypothesis is at present unproven.

scholarly journals Large-scale changes of the semidiurnal tide along North Atlantic coasts from 1846 to 2018

Ocean Science ◽  
2021 ◽  
Vol 17 (1) ◽  
pp. 17-34
Author(s):  
Lucia Pineau-Guillou ◽  
Pascal Lazure ◽  
Guy Wöppelmann
Keyword(s):  
Sea Level ◽  
North Atlantic ◽  
Large Scale ◽  
Low Frequency ◽  
Underlying Mechanism ◽  
East Atlantic ◽  
North West ◽  
North East ◽  
The North ◽  
The North Atlantic

Abstract. We investigated the long-term changes of the principal tidal component M2 along North Atlantic coasts, from 1846 to 2018. We analysed 18 tide gauges with time series starting no later than 1940. The longest is Brest with 165 years of observations. We carefully processed the data, particularly to remove the 18.6-year nodal modulation. We found that M2 variations are consistent at all the stations in the North-East Atlantic (Cuxhaven, Delfzijl, Hoek van Holland, Newlyn, Brest), whereas some discrepancies appear in the North-West Atlantic. The changes started long before the 20th century and are not linear. The secular trends in M2 amplitude vary from one station to another; most of them are positive, up to 2.5 mm/yr at Wilmington since 1910. Since 1990, the trends switch from positive to negative values in the North-East Atlantic. Concerning the possible causes of the observed changes, the similarity between the North Atlantic Oscillation and M2 variations in the North-East Atlantic suggests a possible influence of the large-scale atmospheric circulation on the tide. Our statistical analysis confirms large correlations at all the stations in the North-East Atlantic. We discuss a possible underlying mechanism. A different spatial distribution of mean sea level (corresponding to water depth) from one year to another, depending on the low-frequency sea-level pressure patterns, could impact the propagation of the tide in the North Atlantic basin. However, the hypothesis is at present unproven.

scholarly journals The North Atlantic Oscillation Response to Large-Scale Atmospheric Anomalies in the Northeastern Pacific

2013 ◽  
Vol 70 (9) ◽  
pp. 2854-2874 ◽  
Author(s):  
Marie Drouard ◽  
Gwendal Rivière ◽  
Philippe Arbogast
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Wave Breaking ◽  
Large Scale ◽  
Wave Train ◽  
Low Frequency ◽  
The North ◽  
Northeastern Pacific ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

Abstract Ingredients in the North Pacific flow influencing Rossby wave breakings in the North Atlantic and the intraseasonal variations of the North Atlantic Oscillation (NAO) are investigated using both reanalysis data and a three-level quasigeostrophic model on the sphere. First, a long-term run is shown to reproduce the observed relationship between the nature of the synoptic wave breaking and the phase of the NAO. Furthermore, a large-scale, low-frequency ridge anomaly is identified in the northeastern Pacific in the days prior to the maximum of the positive NAO phase both in the reanalysis and in the model. A large-scale northeastern Pacific trough anomaly is observed during the negative NAO phase but does not systematically precede it. Then, short-term linear and nonlinear simulations are performed to understand how the large-scale ridge anomaly can act as a precursor of the positive NAO phase. The numerical setup allows for analysis of the propagation of synoptic waves in the eastern Pacific in the presence of a large-scale ridge or trough anomaly and their downstream impact onto the Atlantic jet when they break. The ridge acts in two ways. First, it tends to prevent the downstream propagation of small waves compared to long waves. Second, it deflects the propagation of the wave trains in such a way that they mainly propagate equatorward in the Atlantic. The two modes of action favor the anticyclonic wave breaking and, therefore, the positive NAO phase. With the trough, the wave train propagation is more zonal, disturbances are more meridionally elongated, and cyclonic wave breaking is more frequent in the Atlantic than in the ridge case.

scholarly journals Population genetics meets phylogenetics: new insights into the relationships among members of the genus Euthynnus (family Scombridae)

Hydrobiologia ◽  
2021 ◽  
Author(s):  
Judith Ollé ◽  
Laura Vilà-Valls ◽  
Jaime Alvarado-Bremer ◽  
Genoveva Cerdenares ◽  
Thuy Yen Duong ◽  
...  
Keyword(s):  
North Atlantic ◽  
Genetic Divergence ◽  
East Atlantic ◽  
North West ◽  
North East ◽  
The North ◽  
Worldwide Distribution ◽  
Allopatric Species ◽  
The North Atlantic ◽  
High Level

AbstractEuthynnus (family Scombridae) is a genus of marine pelagic fish species with a worldwide distribution that comprises three allopatric species: E. alletteratus, E. affinis and E. lineatus. All of them targeted by artisanal and commercial fisheries. We analyzed 263 individuals from Atlantic and Pacific Oceans using two genetic markers, the mtDNA Control Region (350 bp) and nuclear calmodulin (341 bp). The results obtained challenge the phylogeny of this group. We found a deep genetic divergence, probably at species level, within E. alletteratus, between the North Atlantic-Mediterranean and the Tropical East Atlantic. This deep genetic divergence was tested with several species delimitation methods. This complete phylogeographic association between the North Atlantic and the Tropical East Atlantic support the hypothesis of two cryptic species. In addition, population genetic heterogeneity was detected between the North East Atlantic–Mediterranean and North West Atlantic regions. Our results indicate two scales of differentiation in what is currently considered a single population. Accordingly, for management purposes, the populations of E. alletteratus, should be divided into a minimum of three management units. On the other hand, the high level of differentiation found in E. alletteratus contrasts with the shallow genetic divergence of E. affinis and E. lineatus.

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.

The Role of Extratropical Air–Sea Interaction in the Autumn Subseasonal Variability of the North Atlantic Oscillation

2019 ◽  
Vol 32 (22) ◽  
pp. 7697-7712 ◽  
Author(s):  
Yu Nie ◽  
Hong-Li Ren ◽  
Yang Zhang
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Gulf Stream ◽  
Low Frequency ◽  
Mean Flow ◽  
The North ◽  
Subseasonal Variability ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

Abstract Considerable progress has been made in understanding the internal eddy–mean flow feedback in the subseasonal variability of the North Atlantic Oscillation (NAO) during winter. Using daily atmospheric and oceanic reanalysis data, this study highlights the role of extratropical air–sea interaction in the NAO variability during autumn when the daily sea surface temperature (SST) variability is more active and eddy–mean flow interactions are still relevant. Our analysis shows that a horseshoe-like SST tripolar pattern in the North Atlantic Ocean, marked by a cold anomaly in the Gulf Stream and two warm anomalies to the south of the Gulf Stream and off the western coast of northern Europe, can induce a quasi-barotropic NAO-like atmospheric response through eddy-mediated processes. An initial southwest–northeast tripolar geopotential anomaly in the North Atlantic forces this horseshoe-like SST anomaly tripole. Then the SST anomalies, through surface heat flux exchange, alter the spatial patterns of the lower-tropospheric temperature and thus baroclinicity anomalies, which are manifested as the midlatitude baroclinicity shifted poleward and reduced baroclinicity poleward of 70°N. In response to such changes of the lower-level baroclinicity, anomalous synoptic eddy generation, eddy kinetic energy, and eddy momentum forcing in the midlatitudes all shift poleward. Meanwhile, the 10–30-day low-frequency anticyclonic wave activities in the high latitudes decrease significantly. We illustrate that both the latitudinal displacement of midlatitude synoptic eddy activities and intensity variation of high-latitude low-frequency wave activities contribute to inducing the NAO-like anomalies.

scholarly journals Cyclones causing wind storms in the Mediterranean: characteristics, trends and links to large-scale patterns

2010 ◽  
Vol 10 (7) ◽  
pp. 1379-1391 ◽  
Author(s):  
K. M. Nissen ◽  
G. C. Leckebusch ◽  
J. G. Pinto ◽  
D. Renggli ◽  
S. Ulbrich ◽  
...  
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Positive Phase ◽  
East Atlantic ◽  
The North ◽  
The North Atlantic ◽  
Wind Storms ◽  
The Mediterranean ◽  
Wind Events ◽  
The North Atlantic Oscillation

Abstract. A climatology of cyclones with a focus on their relation to wind storm tracks in the Mediterranean region (MR) is presented. Trends in the frequency of cyclones and wind storms, as well as variations associated with the North Atlantic Oscillation (NAO), the East Atlantic/West Russian (EAWR) and the Scandinavian variability pattern (SCAND) are discussed. The study is based on the ERA40 reanalysis dataset. Wind storm tracks are identified by tracking clusters of adjacent grid boxes characterised by extremely high local wind speeds. The wind track is assigned to a cyclone track independently identified with an objective scheme. Areas with high wind activity – quantified by extreme wind tracks – are typically located south of the Golf of Genoa, south of Cyprus, southeast of Sicily and west of the Iberian Peninsula. About 69% of the wind storms are caused by cyclones located in the Mediterranean region, while the remaining 31% can be attributed to North Atlantic or Northern European cyclones. The North Atlantic Oscillation, the East Atlantic/West Russian pattern and the Scandinavian pattern all influence the amount and spatial distribution of wind inducing cyclones and wind events in the MR. The strongest signals exist for the NAO and the EAWR pattern, which are both associated with an increase in the number of organised strong wind events in the eastern MR during their positive phase. On the other hand, the storm numbers decrease over the western MR for the positive phase of the NAO and over the central MR during the positive phase of the EAWR pattern. The positive phase of the Scandinavian pattern is associated with a decrease in the number of winter wind storms over most of the MR. A third of the trends in the number of wind storms and wind producing cyclones during the winter season of the ERA40 period may be attributed to the variability of the North Atlantic Oscillation.

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.

scholarly journals Winter Cyclone Regimes Over The North Atlantic

2021 ◽  
Author(s):  
Veronika N. Maslova ◽  
Elena N. Voskresenskaya ◽  
Alexander V. Yurovsky ◽  
Mikhail Yu. Bardin
Keyword(s):  
North Atlantic ◽  
Reanalysis Data ◽  
East Atlantic ◽  
Teleconnection Patterns ◽  
The Third ◽  
The North ◽  
Function Decomposition ◽  
Spectral Peaks ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

Abstract To study regimes of winter cyclones in the North Atlantic, empirical orthogonal function decomposition was applied separately to the frequency, depth and area of cyclones obtained using 6-hourly NCEP/NCAR reanalysis data in 1952–2017 and the developed methodology. The first mode represented the opposite changes of cyclone anomalies in the northern and southern/central North Atlantic. The second mode was characterized by the greatest regional anomalies between its phases over Europe, off its coast and over the Mediterranean. The greatest changes of anomalies for the third modes were in temperate latitudes, both over the ocean and Europe. Linear trends were significant only for the first modes of cyclone parameters. The largest part of variability (74–90% of dispersion) of all cyclone modes corresponded to the periods up to 15 years and was used for spectral analysis, which identified significant spectral peaks: 2.5–3, 4.5, 6 and 8.5 years. These periods coincided with spectral peaks of the main interannual climate signals. Regression analysis allowed to identify the sets of teleconnection patterns responsible jointly for 60–85% of dispersion of the first cyclone modes. The North Atlantic Oscillation and Arctic Oscillation were the main patterns for the first modes of the cyclone parameters. For the second and third frequency modes, the East Atlantic (EA) pattern and a combination of the East Atlantic/West Russia (EA/WR) and Scandinavia patterns played the major role, respectively. As for the third depth and area modes, the association with the EA and EA/WR patterns was shown, respectively.

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