Experimental Determination of Properties of the Scholte Wave in the Bottom of the North Sea

Author(s):  
Florian Schirmer

Records of sea level for several North Sea ports for the winter of 1953-4 have been in vestigated. They were split into 14-day intervals, and each 14-day record was Fourieranalyzed to determine if any non-astronomical periods were present. There was evidence of some activity between 40 and 50 h period, and a determination of the phase angles at different ports showed that the activity could be due to a disturbance travelling southwards from the north of the North Sea. The disturbance was partly reflected somewhere near the line from Lowestoft to Flushing, so that one part returned past Flushing and Esbjerg towards Bergen while the other part travelled towards Dover, and there was evidence of its existence on the sea-current records taken near St Margaret's Bay. These results were confirmed by subtracting the predicted astronomical tidal levels from the observed values of sea level and cross-correlating the residuals so obtained for each port with those found at Lowestoft. The residuals at Lowestoft and Aberdeen were compared with the meteorological conditions, and it was found that, although they could be attributed to a large extent to conditions within the North Sea, there was an additional effect due to a travelling surge which was of the same order of magnitude at both Lowestoft and Aberdeen and which was closely related to the rate of change with time of the atmospheric pressure difference between Wick and Bergen.


1988 ◽  
Vol 41 (02) ◽  
pp. 149-173 ◽  
Author(s):  
K. F. Woodman ◽  
J. Juleff ◽  
R. A. Allen

A mainly theoretical study has been undertaken to demonstrate how the extent of cover from a hyperbolic navigation system chain can be evaluated. The impetus for the study was the need to assess how Loran-C could be extended over Western Europe, particularly in the South western Approaches, North Sea, English Channel and Bay of Biscay sea areas.The technique described in this article leads to an accurate determination of the electric field strength at a distance from each transmitting site and takes into account the complexities of the ground-wave propagation path. This field-strength contour is combined with the geometric effects of station siting (expansion factors) to yield a constant S/N contour (–10 dB) which defines the ¼n.m. error and hence the limit of cover for the hyperbolic chain under study.In order to exercise the analytical methods a hypothetical Loran-C chain was studied comprising a master station at Lessay (France), with secondary stations at Soustons (also in France), at Sylt (dual rated; off the North Sea coast of Germany, near the Danish border) and at a fourth station located in north-west Britain on the Hebridean island of Barra. The study indicated that such a hypothetical chain would significantly improve Loran-C cover over much of western Europe.


1993 ◽  
Vol 347 (8-9) ◽  
pp. 324-329 ◽  
Author(s):  
P. Krause ◽  
M. Kriews ◽  
W. Dannecker ◽  
C.-D. Garbe-Sch�nberg ◽  
M. Kersten

1830 ◽  
Vol 120 ◽  
pp. 59-68

In November 1827 I received a special commission from General Bolivar to make a survey of the Isthmus of Panamá and Darien, in order to ascertain the best and most eligible line for a communication (whether by road or canal) between the two seas. On my arrival in Panamá in March 1828 I was joined by a brother officer of Engineers, a Swede in the Colombian service, a good mathematician and of habits of great correctness in observation. Upon consulting together, we found that we could combine the particular object of the commission with a second object in which we both felt a deep interest, namely, the determination of the relative height of the ocean on either side of the Isthmus; and that we could best accomplish both, by taking a part of the present line of road between Porto Velo and Panamá, until we should fall in with the river Chagres about twenty miles above Cruces, which village is the usual landing-place for all articles of commerce in their transit from the North Sea to Panamá.


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