Mesoscale structures, fluxes and water mass variability in the German Bight as exemplified in the KUSTOS- experiments and numerical models

Becker, G.; Giese, H.; Isert, K.; König, Peter; Langenberg, Heike; Pohlmann, T.; Schrum, Corinna

doi:10.1007/bf02764173

Cited by 30 publications

(29 citation statements)

References 17 publications

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“…). The distribution of temperature and salinity in the bottom layers of the German Bight is strongly related to topography, and follows the ancient Elbe River Valley (Becker et al ). The German Bight is dominated by a counterclockwise residual circulation pattern, which carries a mixture of Atlantic water and continental runoff from the Elbe, the Rhine, and several other rivers into the German Bight from the west (Hickel et al ; van Beusekom et al ).…”

Section: Methodsmentioning

confidence: 99%

“…The German Bight is dominated by a counterclockwise residual circulation pattern, which carries a mixture of Atlantic water and continental runoff from the Elbe, the Rhine, and several other rivers into the German Bight from the west (Hickel et al ; van Beusekom et al ). While the central part of the North Sea is seasonally stratified, the southeast German Bight and the Wadden Sea regions are generally well mixed due to strong tidal currents (Becker et al ).…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Intertidal regions changing coastal alkalinity: The Wadden Sea‐North Sea tidally coupled bioreactor

Voynova

Petersen

Gehrung

et al. 2018

Limnology & Oceanography

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In this study, we successfully implemented a total alkalinity (TA) analyzer in a flow-through setup, in combination with a FerryBox. The high-frequency (10 min) measurements along our ship's route revealed that in coastal systems, where carbon fluxes are dynamic, TA can differ significantly (by up to 100 μmol kg −1 ) between the nearshore and adjacent coastal regions. Even though this study could not account for the net yearly TA production in the coastal region, it demonstrated that there was a seasonal increase in TA of 100-150 μmol kg −1 in coastal waters of the North Sea, equivalent to TA production of 11.7-26.8 mmol m −2 d −1 during the spring and summer months. This seasonal change could not be accounted for by riverine contributions, but instead was probably related to seasonal organic matter production and processing in coastal and nearshore regions. Bottom sediments and the tidally coupled biogeochemical reactor between coastal (North Sea) and nearshore (Wadden Sea) regions are mediating this TA change, and the~4 months lag between the seasonal increase in alkalinity and the peak organic matter production could be explained by the supply of (labile) organic matter and its temperature-dependent remineralization via both aerobic and anaerobic pathways.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Intertidal regions changing coastal alkalinity: The Wadden Sea‐North Sea tidally coupled bioreactor

Voynova

Petersen

Gehrung

et al. 2018

Limnology & Oceanography

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“…Elbe, Weser, and Ems create an estuarine frontal system, which affects a large area in the German Bight. In the eastern part of the German Bight, close to the North Frisian coast, the combination of riverine freshwater and saline water, which is transported by southwesterly winds into the German Bight, leads to a frontal zone with a strong haline gradient (Becker et al, 1999;Skov and Prins, 2001). That results in strong density gradients which can concentrate floating materials like FML along the density front (Carlson et al, 2018;D'Asaro et al, 2018).…”

Section: Study Areamentioning

confidence: 99%

A State-of-the-Art Compact Surface Drifter Reveals Pathways of Floating Marine Litter in the German Bight

et al. 2019

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Lagrangian observations are important for the understanding of complex transport patterns of floating macroscopic litter items at the ocean surface. Satellite-tracked drifters and numerical models are an important source of information relevant to transport processes as well as distribution patterns of floating marine litter (FML) on a regional to global scale. Sub-mesoscale processes in coastal and estuarine systems have an enormous impact on pathways and accumulation zones of FML and are yet to be fully understood. Here we present a state-of-the-art, low-cost and robust design of a satellite-tracked drifter applicable in studying complex pathways and sub-mesoscale dynamics of floating litter in tidally influenced coastal and estuarine systems. It is compact, lightweight <5 kg, capable of refloating, easily recovered and modified. The drifter motion resolves currents of the ocean surface layer (top 0.5 m layer) taking into account wind induced motions. We further showcase findings from seven of our custom-made drifters deployed from RV Heincke and RV Senckenberg in the German Bight during spring and autumn 2017. Drifter velocities were computed from high resolved drifter position data and compared to local wind field observations. It was noted that the net transport of the drifters in areas far away from the coast was dominated by wind-driven surface currents, 1% of the wind speed, whereas the transport pattern in coastal areas was mainly overshadowed by local small-scale processes like tidal jet currents, interactions with a complex shoreline and fronts generated by riverine freshwater plumes.

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“…Corrado et al, 2017). Initial separations of drifter pairs we analyse are much below the local internal radius of deformation, which in the German Bight is in the range of approximately 2-20 km (Becker et al, 1983(Becker et al, , 1999Badin et al, 2009). Therefore our experiments explore the sub-mesoscale regime in which geostrophic horizontal turbulence interacts with vertical mixing (e.g.…”

Section: Introductionmentioning

confidence: 99%

Submesoscale dispersion of surface drifters in a coastal sea near offshore wind farms

Callies¹,

Carrasco²,

Floeter³

et al. 2018

Preprint

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Abstract. We analyse relative dispersion of surface drifters released as pairs (6 instances) or triplets (2 instances) during three field experiments in the German Bight in close proximity to wind farms. Drifter pairs can be classified in a remarkably clear way into those with spatial separation growing either exponentially or non-monotonously. There is some tentative evidence that exponential relative dispersion growth rates preferably occur for drifter pairs that are most exposed to the possible influence of a wind farm. Kinetic energy spectra and velocity structure functions suggest that turbulent energy could be injected by tides, possibly also via an interaction between tidal currents and wind turbine towers. Applicability of inertial range turbulence theory, however, can be doubted given distinct peaks of overtides observed in velocity power spectra. More comprehensive studies would be needed to better separate submesoscale effects of wind farms, tides and possibly baroclinic instabilities on observed drifter behaviour in a complex coastal environment.

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Mesoscale structures, fluxes and water mass variability in the German Bight as exemplified in the KUSTOS- experiments and numerical models

Cited by 30 publications

References 17 publications

Intertidal regions changing coastal alkalinity: The Wadden Sea‐North Sea tidally coupled bioreactor

Intertidal regions changing coastal alkalinity: The Wadden Sea‐North Sea tidally coupled bioreactor

A State-of-the-Art Compact Surface Drifter Reveals Pathways of Floating Marine Litter in the German Bight

Submesoscale dispersion of surface drifters in a coastal sea near offshore wind farms

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