Review of the physical oceanography of the North Sea

Otto, L.; Zimmerman, J. T. F.; Furnes, Gunnar Κ.; Mork, Martin; Sætre, Roald; Becker, G.

doi:10.1016/0077-7579(90)90091-t

Cited by 470 publications

(235 citation statements)

References 93 publications

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“…These observations and the general circulation patterns of the northern North Sea as described in Otto et al (1990), would indicate association of the 1994 bloom with higher salinity Atlantic water, rather than low-salinity run-off from the Norwegian fjords.…”

Section: The Relationship Between Hydrography and The Origin Of The Bmentioning

confidence: 87%

“…In the current study, the prevailing cloudy weather conditions, both prior to and during the study period, prevented satellite imagery being used to indicate the stage or evolution of the bloom. Tidal streams in the northern North Sea are generally low (Otto et al, 1990) and it may well be that wind stress is an important feature in the origin of bloom formation in this area (Pingree and Griffiths, 1982). During summer, the seasonal western displacement of the Norwegian Coastal Water is due to the Ekman transport driven by increased northerly wind stress (Saetre et al, 1988).…”

Section: The Relationship Between Hydrography and The Origin Of The Bmentioning

confidence: 99%

“…During summer, the seasonal western displacement of the Norwegian Coastal Water is due to the Ekman transport driven by increased northerly wind stress (Saetre et al, 1988). The outflow from fjords can be very pronounced and long periods of northerly winds can produce plumes of brackish water >80 km offshore (Otto et al, 1990).…”

Section: The Relationship Between Hydrography and The Origin Of The Bmentioning

confidence: 99%

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The hydrography and biology of a bloom of the coccolithophorid Emiliania huxleyi in the northern North Sea

Head

Crawford

Egge

et al. 1998

Journal of Sea Research

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In June=July 1994 a study was made of a small bloom of the coccolithophorid Emiliania huxleyi in an area of the North Sea to the east of the Shetland Islands. Observations on the hydrography of the study area indicated the bloom was associated with Atlantic water and was confined to an area in which a stable shallow mixed layer had formed. There was no evidence to suggest association of horizontal physical structure with the bloom development. High cell densities of >1-6 ð 10 6 cells dm 3 , together with low concentrations of PIC (<50 µg dm 3 ) and detached liths (2-3 ð 10 4 liths cm 3 ) indicated that the bloom was studied at an early stage of development. Biochemical and physiological observations indicated active growth was taking place. The results presented are discussed in comparison with previous studies carried out in both oceanic and shelf seas.

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Section: The Relationship Between Hydrography and The Origin Of The Bmentioning

confidence: 87%

Section: The Relationship Between Hydrography and The Origin Of The Bmentioning

confidence: 99%

Section: The Relationship Between Hydrography and The Origin Of The Bmentioning

confidence: 99%

See 1 more Smart Citation

The hydrography and biology of a bloom of the coccolithophorid Emiliania huxleyi in the northern North Sea

Head

Crawford

Egge

et al. 1998

Journal of Sea Research

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“…These large, autumn seabed variations in TLB either were generated by horizontal advection or by bubble-induced overturning or entrainment of warmer water from the upper mixed-layer. However, creation of the observed temperature pattern would require a front of sharply different seabed water masses to repeatedly cross the 22/4b site -a North Sea equivalent of the Gulf Stream -yet oceanographic data for the deeper water-column (Berx and Hughes, 2009;Otto et al, 1990) do not indicate such a persistent oceanographic feature in the central North Sea. This makes horizontal advection a very unlikely mechanism contrary to bubbleinduced overturning or entrainment.…”

Section: Time-series Analysismentioning

confidence: 99%

“…Due to nonlinear interactions between the tidal components and topography, a residual circulation is driven in the same direction as the tidal wave, which enters the North Sea in the Northwest from the Atlantic and in the South through the English Channel and follows an anti-clockwise circulation (Nauw et al, 2015;Otto et al, 1990). At the 22/4b site, the M2 tidal current is (uM2, vM2)=(0.04, 0.23) m/s and the S2 tidal current is (uS2, vS2)=(0.02, 0.09) m/s, derived from results of the OSU Tidal Prediction Model Software applied to the European Shelf (Egbert et al, 2010).…”

Section: Circulation In the Northern North Seamentioning

confidence: 99%

Bubble momentum plume as a possible mechanism for an early breakdown of the seasonal stratification in the northern North Sea

Nauw

Линке

Leifer

2015

Marine and Petroleum Geology

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The presence of a seasonal thermocline likely plays a key role in restraining methane released from a seabed source in the deeper water column, thereby inhibiting exchange to the atmosphere. The bubble plume itself, however, generates an upward motion of fluid, e.g. upwelling and may thereby be partially responsible for an early breakdown of the seasonal thermocline. Measurements at site 22/4b, located at (57 o 55'N, 1 o 38'E) in the UK Central North Sea, 200 km east of the Scottish mainland, where gas is still being released since a blow out in 1990, have been used to identify the generation of the seasonal thermocline, and thus, the depth of the upper mixed layer and its breakdown in autumn. Data derived from two landers, containing an Acoustic Doppler Current Profiler and a Conductivity Temperature Depth recorder, were used to determine the mixed layer depth and the breakdown of the thermocline. Mixing of upper layer fluid into the lower layer has been inferred from large amplitude variations in the near-bottom temperature. The ADCPs estimate velocity profiles in four beam directions using Doppler shifted frequency from acoustic pings sent out and received by four different transducers in a specific configuration. Besides that, the intensity of the backscattered sound per transducer is also recorded. Bubbles from the nearby plume contaminate the signal during part of the tidal cycle, but in bubble free periods, the mixed layer depth can be estimated using the acoustic backscatter signal as local maxima. Results show that the thermocline broke down between mid-October and early November, several weeks earlier than the breakdown of the thermocline in nearby/comparable areas, likely caused by bubble-induced downwelling at the site. The early breakdown of the thermocline was accompanied by multiple occurrence of a strong jet-like structure, associated with the seasonal tidal mixing front. 2

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Variability of North Sea pH and CO₂ in response to North Atlantic Oscillation forcing

et al. 2013

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[1] High biological activity causes a distinct seasonality of surface water pH in the North Sea, which is a strong sink for atmospheric CO 2 via an effective shelf pump. The intimate connection between the North Sea and the North Atlantic Ocean suggests that the variability of the CO 2 system of the North Atlantic Ocean may, in part, be responsible for the observed variability of pH and CO 2 in the North Sea. In this work, we demonstrate the role of the North Atlantic Oscillation (NAO), the dominant climate mode for the North Atlantic, in governing this variability. Based on three extensive observational records covering the relevant levels of the NAO index, we provide evidence that the North Sea pH and CO 2 system strongly responds to external and internal expressions of the NAO. Under positive NAO, the higher rates of inflow of water from the North Atlantic Ocean and the Baltic outflow lead to a strengthened north-south biogeochemical divide. The limited mixing between the north and south leads to a steeper gradient in pH and partial pressure of CO 2 (pCO 2 ) between the two regions in the productive period. This is exacerbated further when coinciding with higher sea surface temperature, which concentrates the net community production in the north through shallower stratification. These effects can be obscured by changing properties of the constituent North Sea water masses, which are also influenced by NAO. Our results highlight the importance of examining interannual trends in the North Sea CO 2 system with consideration of the NAO state.Citation: Salt, L. A

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Review of the physical oceanography of the North Sea

Cited by 470 publications

References 93 publications

The hydrography and biology of a bloom of the coccolithophorid Emiliania huxleyi in the northern North Sea

The hydrography and biology of a bloom of the coccolithophorid Emiliania huxleyi in the northern North Sea

Bubble momentum plume as a possible mechanism for an early breakdown of the seasonal stratification in the northern North Sea

Variability of North Sea pH and CO₂ in response to North Atlantic Oscillation forcing

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Review of the physical oceanography of the North Sea

Cited by 470 publications

References 93 publications

The hydrography and biology of a bloom of the coccolithophorid Emiliania huxleyi in the northern North Sea

The hydrography and biology of a bloom of the coccolithophorid Emiliania huxleyi in the northern North Sea

Bubble momentum plume as a possible mechanism for an early breakdown of the seasonal stratification in the northern North Sea

Variability of North Sea pH and CO2 in response to North Atlantic Oscillation forcing

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Variability of North Sea pH and CO₂ in response to North Atlantic Oscillation forcing