A Composite View of the North Sea Ecosystem and Future Research Needs

Oceanographically based mechanisms are shown to explain the spatial variation in the climatic relationship between the abundance of medusae (Aurelia aurita and Cyanea spp. of the class Scyphozoa), in the North Sea between 1971 and 1986 during June–August, and the winter (December–March) North Atlantic Oscillation Index (NAOI). A scyphomedusa population to the west of Denmark shows a strong inverse relationship between medusa abundance and fluctuations in the NAOI; the NAOI correlates strongly (P < 0.001) with both annual sea surface temperature (SST) at 6.5°E 56.5°N (1950–2008) and with winter precipitation on the Danish coast at Nordby (1900–2008) suggesting a direct link between the influence of climate and medusae abundance. In contrast, scyphomedusa abundance and distribution in the northern North Sea appears to be influenced by oceanic and mixed water inflow, which may overwhelm or mask any direct climatic influence on jellyfish abundance. Similarly, advection can also explain much of the interannual variability (1959–2000) in the abundance of other gelatinous zooplankton taxa (Cnidaria, Ctenophora and Siphonophora) in the northern North Sea as identified by the capture of gelatinous tissue and nematocysts (stinging cells) in Continuous Plankton Recorder samples. Jellyfish (Scyphozoa) in the southern North Sea may benefit from low temperature anomalies and the long-term effects of global warming might suppress Aurelia aurita and Cyanea spp. populations there. However, the biological response to temperature is complex and future research is required in this area.

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A two-dimensional numerical sea model

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1969.0041 ◽

1969 ◽

Vol 265 (1160) ◽

pp. 93-137 ◽

Cited By ~ 124

Keyword(s):

North Sea ◽

Numerical Models ◽

Storm Surges ◽

Future Research ◽

The North ◽

Contour Lines ◽

Algol Program ◽

Shelf Sea ◽

The North Sea ◽

Forecasting System

The model has, in the first place, been developed for the detailed investigation of various types of North Sea storm surge, particularly the external surge. As in some earlier investigations the linearized hydrodynamical equations are solved numerically by using a finite-difference grid and a step-by-step procedure in time. However, a special feature of the present approach is that, within the basic grid system, it is possible to choose a general form of sea boundary: the computations are then carried out accordingly, on a digital computer, using an Algol program . In this sense the aim has been to develop a numerical tool of fairly wide application for the study of surge and tidal phenomena in adjacent seas. For the North Sea, surges experienced at several ports around the shores of the Sea have been compared with those derived numerically. Also, contour lines of sea-level disturbance have been drawn showing patterns of surge development. Perhaps for the first time, the continental shelf sea surrounding the British Isles has been treated as a single dynamical unit, and the influence of flow through the Strait of Dover on surge levels in the North Sea has been studied. The work has laid out guide lines for future research involving the application of numerical models to problems of storm surges and tides in British waters. A first step has been taken towards the establishment of a surge forecasting system for the east coast o f England based on dynamical principles.

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The north sea storm surge of 31 January and 1 February 1953

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1954.0002 ◽

1954 ◽

Vol 246 (915) ◽

pp. 371-400 ◽

Cited By ~ 46

Keyword(s):

Storm Surge ◽

North Sea ◽

Frictional Coefficient ◽

Future Research ◽

English Channel ◽

Tractive Force ◽

The North ◽

The North Sea ◽

The Mean ◽

Sea Storm

Using observed hourly heights of tide at thirty-one stations in the North Sea and two in the English Channel, the storm surge of 31 January and 1 February 1953 has been investigated in the light of the meteorological conditions prevailing. The major cause of the disturbance is shown to be the strong northerly winds in and to the north of the North Sea, modified at each station by local wind and barometric effects. An increase of 2 ft. in the mean level of the North Sea during the disturbance has been deduced, and the response of the sea as a whole to the disturbing winds has been examined. Geostrophic effects have been remarked in both the growth and decay of the disturbance. Estimates have been made of the air/sea frictional coefficient on two separate occasions during the period considered, assuming the tractive force of the wind to vary as the square of its velocity. These estimates are in agreement with accepted values. The partial transmission of this large surge through the Straits of Dover has been shown as an im portant factor, influencing the levels immediately to the north of the Straits. Prediction of the surge at Southend by a previously established formula has given only fair results, but the errors have been explained in terms of the facts previously presented and the approximations upon which the formula is based. Suggestions for future research into the improvement of surge prediction formulae have been made.

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