Decadal changes in the wind forcing over the North Sea

Siegismund, Frank; Schrum, Corinna

doi:10.3354/cr018039

Cited by 90 publications

(56 citation statements)

References 12 publications

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“…Easterly winds promote the formation of the North Frisian gyre, and of a large cyclonic circulation in the central German Bight, which has substantial influence on the distribution and residence time of pollutants in the south-eastern North Sea (Dippner, 1993). Westerly winds prevail with an average speed of 9 m s − 1 in winter and 6 m s − 1 in summer (Siegismund and Schrum, 2001). On average, one or two major annual storm events occur over the North Sea (Weisse et al, 2005), and these likely have a strong influence on the spatio-temporal distribution of floating objects.…”

Section: Study Areamentioning

confidence: 99%

Spatio-temporal distribution of floating objects in the German Bight (North Sea)

Thiel

Hinojosa

Joschko

et al. 2011

Journal of Sea Research

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Floating objects facilitate the dispersal of marine and terrestrial species but also represent a major environmental hazard in the case of anthropogenic plastic litter. They can be found throughout the world's oceans but information on their abundance and the spatio-temporal dynamics is scarce for many regions of the world. This information, however, is essential to evaluate the ecological role of floating objects. Herein, we report the results from a ship-based visual survey on the abundance and composition of flotsam in the German Bight (North Sea) during the years 2006 to 2008. The aim of this study was to identify potential sources of floating objects and to relate spatio-temporal density variations to environmental conditions. Three major flotsam categories were identified: buoyant seaweed (mainly fucoid brown algae), natural wood and anthropogenic debris. Densities of these floating objects in the German Bight were similar to those reported from other coastal regions of the world. Temporal variations in flotsam densities are probably the result of seasonal growth cycles of seaweeds and fluctuating river runoff (wood). Higher abundances were often found in areas where coastal fronts and eddies develop during calm weather conditions. Accordingly, flotsam densities were often higher in the inner German Bight than in areas farther offshore. Import of floating objects and retention times in the German Bight are influenced by wind force and direction. Our results indicate that a substantial amount of floating objects is of coastal origin or introduced into the German Bight from western source areas such as the British Channel. Rapid transport of floating objects through the German Bight is driven by strong westerly winds and likely facilitates dispersal of associated organisms and gene flow among distant populations.

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Section: Study Areamentioning

confidence: 99%

Spatio-temporal distribution of floating objects in the German Bight (North Sea)

Thiel

Hinojosa

Joschko

et al. 2011

Journal of Sea Research

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“…Consequently, the area east of 6.5 • E is the eastern part. Prevailing westerly winds (Siegismund and Schrum, 2001) and the counter-clockwise tidal wave result in an eastward mean current that closely follows the coastline ). Winds and tides also keep this shallow coastal sea with water depths below 40 m well mixed throughout most of the year.…”

Section: Study Areamentioning

confidence: 99%

Interannual variability of alongshore spring bloom dynamics in a coastal sea caused by the differential influence of hydrodynamics and light climate

Brandt¹,

Wirtz²

2010

Biogeosciences

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Abstract. Timing and spatial distribution of phytoplankton blooms in coastal oceans are highly variable. The interactions of various biological and physical factors leading to the observed variability are complex and remain poorly understood. We present an example for distinct differences in the spatio-temporal chlorophyll a (CHL-a ) distribution on an interannual scale, integrating high-frequency data from an autonomous measuring device (FerryBox), which operated on an alongshore route in the coastal German Bight (North Sea). While in one year the distribution of CHL-a was spatially homogeneous (2004), a bloom only developed in one part of the transect in the following spring period (2005). We use a one-dimensional Lagrangian particle tracking model, which operates along the mean current direction, combined with a NPZ-model to identify the mechanisms controlling the observed interannual bloom variability on the alongshore transect. Our results clearly indicate that in 2004 the local light climate determined the spatial and temporal dynamics of the spring bloom. In contrast, the import of a water mass with elevated CHL-a concentrations from the adjacent Southern Bight triggered the spring bloom in 2005. The inflow event did, however, not last long enough to spread the bloom into the eastern part of the study area, where high turbidity prevented local phytoplankton growth. The model identifies two interacting mechanisms, light climate and hydrodynamics, that controlled the alongshore dynamics. Especially the occurrence of a pronounced spring bloom despite unfavourable light conditions in 2005 underlines the need to carefully consider hydrodynamics to understand the dynamics of the plankton community in coastal environments.

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“…This is visible in the larger increase in winds towards the north. When looking at the variation in the wind density function, as defined in Siegismund and Schrum (2001), an increase in frequency or in intensity of west-south-western winds was also visible over decades. This agrees with the results obtained in Siegismund and Schrum (2001).…”

Section: Introduction and Average Valuesmentioning

confidence: 99%

“…When looking at the variation in the wind density function, as defined in Siegismund and Schrum (2001), an increase in frequency or in intensity of west-south-western winds was also visible over decades. This agrees with the results obtained in Siegismund and Schrum (2001). The analysis further showed that the strongest winds occur in the months of November to February, although no clear seasonal difference in wind direction occurred.…”

Section: Introduction and Average Valuesmentioning

confidence: 99%

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Evolution of marine storminess in the Belgian part of the North Sea

Eynde

Sutter

Haerens

2012

Nat. Hazards Earth Syst. Sci.

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Abstract.Severe storms have affected European coast lines in the past but knowledge on changes in storminess for the last decades is still sparse. Climate change is assumed to be a main driving factor with the potential to induce changes on the intensity, duration and frequency of powerful marine storms, including a long-term influence on peak wind speeds, surges and waves. It is, therefore, important to investigate whether in the last decades changes in the magnitude of storms, their duration and frequency could be observed. Understanding trends in storminess in the last decades will help to better prepare coastal managers for future events, taking into account potential changes on storm occurrence and magnitude to improve planning of mitigation and adaptation strategies. The purpose of this study was to focus on the evolution of extreme wind conditions, wave height and storm surge levels in the North Sea Region, especially in the Belgian part of the North Sea (BPNS). Based on the analysis performed it is concluded that no clear trend can be observed for the occurrence of significant increasing extreme wind speeds over the BPNS. Furthermore, one can conclude that not enough scientific evidence is available to support scenarios with increased wave height or storminess.

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Decadal changes in the wind forcing over the North Sea

Cited by 90 publications

References 12 publications

Spatio-temporal distribution of floating objects in the German Bight (North Sea)

Spatio-temporal distribution of floating objects in the German Bight (North Sea)

Interannual variability of alongshore spring bloom dynamics in a coastal sea caused by the differential influence of hydrodynamics and light climate

Evolution of marine storminess in the Belgian part of the North Sea

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