The flow of water through the straits of Dover, related to wind and differences in sea level

1956 ◽  
Vol 248 (953) ◽  
pp. 517-551 ◽  
Keyword(s):  
Steady State ◽  
Sea Level ◽  
North Sea ◽  
Sea Water ◽  
Tidal Currents ◽  
English Channel ◽  
Mean Flow ◽  
North East ◽  
The North ◽  
The Difference

The difference in electric potential between the water on opposite sides of the English Channel, as recorded on a telephone cable running from St Margaret’s Bay to Sangatte, has been used to measure the mean flow of water through the Straits of Dover. The records were calibrated by means of the tidal currents, which were know from previous measurements. A p.d. of 1 V corresponds to a current of about 140 cm /s (2.75 knots), the exact calibration depending on the electrical conductivity o f the sea water and having a seasonal variation. Continuous records were obtained during the 15-month period from February 1953 to June 1954. For 4 months, from November 1953 to March 1954, similar records were also obtained on an other cable, crossing the southern North Sea from Aldeburgh to Domburg. Fluctuations due to the Earth currents associated with geomagnetic disturbances occurred from time to time, but did not usually cause any difficulty in in terpretin g the records. The residual flow, after eliminating the tidal currents, has been correlated with the local wind in the Straits and the difference in sea level between the eastern p a rt of the English Channel and the southern part of the North Sea, as determined from tide-gauge records. The tidal currents and elevations were eliminated, approximately, by taking means of 25 hourly readings centred at noon, for each day of the period covered by the observations. The greatest daily rates of flow recorded w ere 79 cm/s (T53 knots) towards the north-east on 1 November 1953 an d 77 cm /s (T49 knots) towards the south-w est on 3 January 1954. F or three periods of un usually strong flow, namely, 19 to 24 September 1953, 26 October to 8 November 1953, and 1 to 6 January 1954, a more detailed analysis was made, eliminating the tidal effects by a method previously used in the analysis of storm surges. The results show the existence of ‘current surges’, the peaks of which lag by up to 6 h behind the corresponding max im a in the wind stress or surface gradient producing them . An attempt has been made to relate the empirical results to the dynamics of flow through the Straits. On the assumption that the 25 h means can be regarded as referring to steady-state conditions, values o f 4-5 x 10<super>-3</super> for the w ind-stress coefficient y<super> 2</super> an d 3-8 x 10<super>-3</super> for the bottom friction coefficient k have been deduced. These rather high values may be due, in part, to the steady-state assumption not being justified. The general features of the current surges are consistent with the dynamical treatment.

scholarly journals NEED Northern European Enclosure Dam

2021 ◽  
Vol 52 (2) ◽  
pp. 6-6
Author(s):  
Sjoerd Groeskamp ◽  
Joakim Kjellsson
Keyword(s):  
Atlantic Ocean ◽  
Sea Level Rise ◽  
Sea Level ◽  
North Sea ◽  
European Countries ◽  
English Channel ◽  
The North ◽  
Northern European ◽  
The North Sea

To protect fifteen northern European countries against sea level rise, a highly ambitious plan was put forward to build massive sea dams across the North Sea and the English Channel, which will cut off the North Sea from the rest of the Atlantic Ocean.

Macrobenthos of a Sublittoral Sandbank in the Southern Bight of the North Sea

1982 ◽  
Vol 62 (3) ◽  
pp. 521-534 ◽  
Author(s):  
C. Vanosmael ◽  
K. A. Willems ◽  
D. Claeys ◽  
M. Vincx ◽  
C. Heip
Keyword(s):  
North Sea ◽  
Tidal Currents ◽  
English Channel ◽  
Marine Transgression ◽  
Sea Floor ◽  
Southern Bight ◽  
Glacial Origin ◽  
The North ◽  
Belgian Coast ◽  
The North Sea

In the Southern Bight of the North Sea, off the Belgian coast, exists a series of parallel sublittoral sandbanks, the Flemish Banks, situated in a southwest-northeastern direction, 15–25 km long and 3–6 km wide. They are separated by channels, 4–6 km wide, and rise about 25 m above the surrounding sea-floor (Fig. 1). These sandbanks resulted from the accumulation of sandy deposits of glacial origin sedimented by the giant stream draining the waters from the present Rhine, Meuse, Scheldt and Thames before the Flandrian marine transgression about 12000 years ago. When from boreal times onwards the North Sea became slowly inundated, a connexion existed with the small English Channel which gradually enlarged, resulting in the very strong tidal currents which are responsible for the present geomorphology of the region.

scholarly journals Numerical modelling of physical processes governing larval transport in the southern North Sea

Ocean Science ◽  
2014 ◽  
Vol 10 (3) ◽  
pp. 357-376 ◽  
Author(s):  
M. C. H. Tiessen ◽  
L. Fernard ◽  
T. Gerkema ◽  
J. van der Molen ◽  
P. Ruardij ◽  
...  
Keyword(s):  
North Sea ◽  
Sea Water ◽  
A Priori ◽  
Three Dimensional ◽  
Larval Transport ◽  
Absolute Amount ◽  
English Channel ◽  
Annual Variability ◽  
The North ◽  
The North Sea

Abstract. A three-dimensional hydrodynamic model (GETM) was coupled with a particle tracking routine (GITM) to study the inter-annual variability in transport paths of particles in the North Sea and English Channel. For validation, a comparison with observed drifter trajectories is also presented here. This research investigated to what extent variability in the hydrodynamic conditions alone (reflecting passive particle transport) contributed to inter-annual variability in the transport of eggs and larvae. In this idealised study, no a priori selection of specific spawning grounds or periods was made and no active behaviour (vertical migration) or mortality was included. In this study, egg and larval development towards coastal nursery areas was based solely on sea water temperature, while settlement areas were defined by a threshold water depth. Results showed strong inter-annual variability in drift direction and distance, caused by a combination of wind speed and direction. Strong inter-annual variability was observed both in absolute amount of settlement in several coastal areas, and in the relative importance of the different areas. The effects of wind and temperature variability are minor for settlement along the western shores of the North Sea and in the English Channel, but have a very significant impact on settlement along the eastern shores of the North Sea. Years with strong south-westerly winds across the Dover Straight resulted in higher settlement figures along its eastern shores of the North Sea (standard deviation 37% of the mean annual settlement value). Settlement in the western Dutch Wadden Sea did not only show inter-annual variability, but patterns were also variable within each year and revealed seasonal changes in the origin of particles: during winter, stronger currents along with colder temperatures generally result in particles originating from further away.

Larval Anisakis simplex (Rudolphi, 1809, det. Krabbe, 1878) and larval Hysterothylacium sp. (Nematoda: Ascaridoidea) in euphausiids (Crustacea: Malacostraca) in the North-East Atlantic and northern North Sea

1983 ◽  
Vol 57 (2) ◽  
pp. 167-177 ◽  
Author(s):  
John W. Smith
Keyword(s):  
North Sea ◽  
Sea Water ◽  
Anisakis Simplex ◽  
High Rate ◽  
East Atlantic ◽  
New Host ◽  
North East ◽  
The North ◽  
Different Temperatures ◽  
Northern North Sea

ABSTRACTOver 26000 specimens representing five euphausiid species collected, mostly in 1969, in the North-East Atlantic and northern North Sea were examined for parasites. Hysterothylacium sp. larvae were rare, occurring in only two euphausiid samples from inshore localities; the 9 larvae found (3.8 to 12.3 mm long) are described and illustrated. Infection with larval Anisakis simplex was virtually restricted to Thysanoessa spp. and appeared to be discontinuous. Infection was absent to the west of Scotland, and rare to the north of Scotland and at the Faroes. Larval A. simplex was not uncommon in offshore regions of the northern North Sea at depths between 100 and 200 m; the prevalence rate there for individual euphausiid species in individual samples was mostly 0 to 40% but an exceptionally high rate of 78.0% was recorded. Larvae in euphausiids do not become encapsulated but appear to remain active. Experimental observations on the sedimentation rate of A. simplex eggs and hatched larvae in sea water at 10°C are discussed in relation to embryonation and hatching at different temperatures, and depth of the sea. New host records are claimed for larval A. simplex in Nyctiplutnes couchii, and for larval Hysterothylacium sp. in Thysanoessa inermis. No individual euphausiid harboured more than one parasite, either larval nematode or ellobiopsid (see also SMITH, 1981). Morphological and morphometric observations on larval A. simplex from euphausiids are reported elsewhere (SMITH, 1983).

Comparative fecundity of North Sea plaice ( Pleuronectes platessa L.)

1986 ◽  
Vol 228 (1253) ◽  
pp. 401-431 ◽  
Keyword(s):  
North Sea ◽  
German Bight ◽  
Relative Weight ◽  
Stage Iv ◽  
Analysis Of Covariance ◽  
Fish Length ◽  
English Channel ◽  
Southern Bight ◽  
The North ◽  
The Difference

Stage IV ovaries of plaice were obtained at sea from five spawning areas of the North Sea and English Channel (Eastern English Channel, Southern Bight, Central Southern North Sea, German Bight and Flamborough) in the years 1977, 1979 and 1980. Additional samples were provided from Dutch landings at IJmuiden for 1972. The numbers of eggs were counted from 790 fish. After a logarithmic transformation, analysis-of-covariance techniques were used to describe the relation between fecundity, given by the number of eggs, and fish length and age, and to examine fecundity differences between spawning area and year. After removing the effects of length and age, significant differences in fecundity were found between years. In the German Bight these were as much as 1.44 times. The data indicate that fecundities at a standard length and age were larger in 1980 than in 1979 but that the extent of the difference varied with spawning location. A gradual decrease in fecundity at a given length and age is shown from the eastern English Channel northwards to the German Bight. A significant decrease in fecundity with age, at a given length, is shown for all locations. Data from the Southern Bight and Flamborough were compared with those collected over the period 1947-9. The recent data from Flamborough show an increase in fecundity at length and age of 1.36 times and from the Southern Bight an increase of 1.6 times is found. The difference in the Southern Bight is reflected in the greater relative weight of the ovaries to body weight in 1980 compared with that in the 1940s. It is suggested that the modulation of fecundity could provide a potentially significant contribution to the natural regulation of the plaice population.

Plymouth Peridinians: II. Exuviella Perforata Gran from the English Channel

1922 ◽  
Vol 12 (4) ◽  
pp. 812-817
Author(s):  
Marie V. Lebour
Keyword(s):  
New Species ◽  
North Sea ◽  
New Record ◽  
Shell Thickness ◽  
Sea Water ◽  
Thick Shell ◽  
English Channel ◽  
The North ◽  
The North Sea ◽  
A New Species

In centrifuging samples of sea water from Plymouth Sound and some of the stations outside, some interesting forms of Exuviella were found. These are all minute, the largest measuring 22 µ in length, and consequently are easily overlooked, although one at least is abundant during the summer months. This species, which is the commonest Exuviella in the Plymouth district, has been identified as Exuviella perforata Gran, described by him from the North Sea (1915), and is a new record for the English Channel. As it appears to be very little known and its structure is unusual in several particulars, the following notes are not without interest.In 1915 Gran (page 99, Fig. 7) describes and figures Exuviella perforata, a new species from the North Sea at a depth of 0–20 metres, occurring in the eastern part with a density of 100–760 specimens per litre. It is roundish oval or nearly circular in shape, measuring 22.5–25 µ long and 21–22.5 µ wide, with a broad girdle and thick shell (thickness of cell 14–17 µ). The character, however, that gives it peculiar distinction is the depression in the centre of each valve, as Gran puts it, “with a sharply confined point-shaped perforated deepening in the centre.” This separates it from any previously known species of Exuviella. The cell contents owing to contraction could not be described in detail, but in a footnote it is stated that living specimens from Arendal in March, 1914, had brown chromatophores. Cleve-Euler (1917) records an Exuviella, which he says may be E. perforata Gran, as occurring frequently in the Skaggerak, from 0 to 100 metres.

COMPARATIVE CHARACTERISTIC OF SEA RADIANCE COEFFICIENT SPECTRA MEASURED REMOTELY IN COASTAL WATERS OF FIVE SEAS

2017 ◽  
Author(s):  
Vera Rostovtseva ◽  
Vera Rostovtseva ◽  
Igor Goncharenko ◽  
Igor Goncharenko ◽  
Dmitrii Khlebnikov ◽  
...  
Keyword(s):  
Sea Water ◽  
Calibration Method ◽  
Aral Sea ◽  
Comparative Characteristic ◽  
The Black Sea ◽  
North East ◽  
The North ◽  
Water Constituents ◽  
Characteristic Features ◽  
The Baltic

Sea radiance coefficient, defined as the ratio of the sunlight reflected by the water bulk to the sunlight illuminating the water surface, is one of the most informative optical characteristics of the seawater that can be obtained by passive remote sensing. We got the sea radiance coefficient spectra by processing the data obtained in measurements from board a moving ship. Using sea radiance coefficient optical spectra it is possible to estimate water constituents concentration and their distribution over the aquatory of interest. However, thus obtained sea radiance coefficient spectra are strongly affected by weather and measurement conditions and needs some calibration. It was shown that practically all the spectra of sea radiance coefficient have some generic peculiarities regardless of the type of sea waters. These peculiarities can be explained by the spectrum of pure sea water absorption. Taking this into account a new calibration method was developed. The measurements were carried out with the portative spectroradiometers from board a ship in the five different seas: at the north-east coast of the Black Sea, in the Gdansk Bay of the Baltic Sea, in the west part of the Aral Sea, in the Kara Sea with the Ob’ Bay and in the Philippine Sea at the coast of Taiwan. The new method of calibration was applied to the obtained spectra of the sea radiance coefficient that enabled us to get the corresponding absorption spectra and estimate the water constituents concentration in every region. The obtained concentration estimates were compared to the values obtained in water samples taken during the same measurement cycle and available data from other investigations. The revealed peculiarities of the sea radiance coefficient spectra in the aquatories under exploration were compared to the corresponding water content and some characteristic features were discussed.

scholarly journals Transboundary geophysical mapping of geological elements and salinity distribution critical for the assessment of future sea water intrusion in response to sea level rise

2012 ◽  
Vol 16 (7) ◽  
pp. 1845-1862 ◽  
Author(s):  
F. Jørgensen ◽  
W. Scheer ◽  
S. Thomsen ◽  
T. O. Sonnenborg ◽  
K. Hinsby ◽  
...  
Keyword(s):  
Groundwater Flow ◽  
Sea Level Rise ◽  
Sea Level ◽  
Preferential Flow ◽  
Sea Water ◽  
Saline Water ◽  
Seismic Survey ◽  
Salinity Distribution ◽  
Geological Structures ◽  
The North

Abstract. Geophysical techniques are increasingly being used as tools for characterising the subsurface, and they are generally required to develop subsurface models that properly delineate the distribution of aquifers and aquitards, salt/freshwater interfaces, and geological structures that affect groundwater flow. In a study area covering 730 km2 across the border between Germany and Denmark, a combination of an airborne electromagnetic survey (performed with the SkyTEM system), a high-resolution seismic survey and borehole logging has been used in an integrated mapping of important geological, physical and chemical features of the subsurface. The spacing between flight lines is 200–250 m which gives a total of about 3200 line km. About 38 km of seismic lines have been collected. Faults bordering a graben structure, buried tunnel valleys, glaciotectonic thrust complexes, marine clay units, and sand aquifers are all examples of geological structures mapped by the geophysical data that control groundwater flow and to some extent hydrochemistry. Additionally, the data provide an excellent picture of the salinity distribution in the area and thus provide important information on the salt/freshwater boundary and the chemical status of groundwater. Although the westernmost part of the study area along the North Sea coast is saturated with saline water and the TEM data therefore are strongly influenced by the increased electrical conductivity there, buried valleys and other geological elements are still revealed. The mapped salinity distribution indicates preferential flow paths through and along specific geological structures within the area. The effects of a future sea level rise on the groundwater system and groundwater chemistry are discussed with special emphasis on the importance of knowing the existence, distribution and geometry of the mapped geological elements, and their control on the groundwater salinity distribution is assessed.

Further Investigation upon the Water Movements in the English Channel. Drift-Bottle Experiments in the Summers of 1927, 1928 and 1929, with Critical Notes on Drift-Bottle Experiments in General.

1930 ◽  
Vol 17 (1) ◽  
pp. 241-275 ◽  
Author(s):  
J. N. Carruthers
Keyword(s):  
Wind Speed ◽  
North Sea ◽  
English Channel ◽  
The North ◽  
Different Types ◽  
The North Sea ◽  
The Common ◽  
Relationship Of ◽  
Great Simplicity ◽  
Simple Surface

In July–August of three different years common surface-floating bottles were set adrift at International Station E2 (49° 27' N.—4° 42' W.). With them, various types of drag-fitted bottles were also put out. The journeys accomplished are discussed, and the striking differences as between year and year in the case of the common surface floaters, and as between the different types in the same year, are commented upon in the light of the prevailing winds. An inter-relationship of great simplicity is deduced between wind speed and the rate of travel of simple surface floating bottles up-Channel and across the North Sea from the results of experiments carried out in four different summers.

Temperature, Salinity and Plankton in the Eastern North Atlantic and Coastal Waters of Britain, 1957.: I. The Characterisation and Distribution of Surface Waters

1963 ◽  
Vol 20 (3) ◽  
pp. 789-826 ◽  
Author(s):  
B. McK. Bary
Keyword(s):  
North Sea ◽  
North Atlantic ◽  
Coastal Waters ◽  
Water Bodies ◽  
English Channel ◽  
Oceanic Water ◽  
Climatic Fluctuations ◽  
The North ◽  
The North Sea ◽  
Eastern North Atlantic

Monthly temperature-salinity diagrams for 1957 have demonstrated that three surface oceanic "water bodies" were consistently present in the eastern North Atlantic; two are regarded as modified North Atlantic Central water which give rise to the third by mixing. As well in the oceanic areas, large and small, high or low salinity patches of water were common. Effects of seasonal climatic fluctuations differed in the several oceanic water bodies. In coastal waters, differences in properties and in seasonal and annual cycles of the properties distinguish the waters from the North Sea, English Channel and the western entrance to the Channel.The geographic distributions of the oceanic waters are consistent with "northern" and "southern" water bodies mixing to form a "transitional" water. Within this distribution there are short-term changes in boundaries and long-term (seasonal) changes in size of the water bodies.Water in the western approaches to the English Channel appeared to be influenced chiefly by the mixed, oceanic transitional water; oceanic influences in the North Sea appear to have been from northern and transitional waters.

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