Towards a vulnerability assessment of the UK and northern European coasts: the role of regional climate variability

2005 ◽  
Vol 363 (1831) ◽  
pp. 1329-1358 ◽  
Author(s):  
M.N Tsimplis ◽  
D.K Woolf ◽  
T.J Osborn ◽  
S Wakelin ◽  
J Wolf ◽  
...  
Keyword(s):  
Sea Level ◽  
Wave Height ◽  
North Sea ◽  
Positive Response ◽  
Sea Level Change ◽  
Empirical Relationships ◽  
Level Change ◽  
The North ◽  
The North Sea ◽  
The Uk

Within the framework of a Tyndall Centre research project, sea level and wave changes around the UK and in the North Sea have been analysed. This paper integrates the results of this project. Many aspects of the contribution of the North Atlantic Oscillation (NAO) to sea level and wave height have been resolved. The NAO is a major forcing parameter for sea-level variability. Strong positive response to increasing NAO was observed in the shallow parts of the North Sea, while slightly negative response was found in the southwest part of the UK. The cause of the strong positive response is mainly the increased westerly winds. The NAO increase during the last decades has affected both the mean sea level and the extreme sea levels in the North Sea. The derived spatial distribution of the NAO-related variability of sea level allows the development of scenarios for future sea level and wave height in the region. Because the response of sea level to the NAO is found to be variable in time across all frequency bands, there is some inherent uncertainty in the use of the empirical relationships to develop scenarios of future sea level. Nevertheless, as it remains uncertain whether the multi-decadal NAO variability is related to climate change, the use of the empirical relationships in developing scenarios is justified. The resulting scenarios demonstrate: (i) that the use of regional estimates of sea level increase the projected range of sea-level change by 50% and (ii) that the contribution of the NAO to winter sea-level variability increases the range of uncertainty by a further 10–20 cm. On the assumption that the general circulation models have some skill in simulating the future NAO change, then the NAO contribution to sea-level change around the UK is expected to be very small (<4 cm) by 2080. Wave heights are also sensitive to the NAO changes, especially in the western coasts of the UK. Under the same scenarios for future NAO changes, the projected significant wave-height changes in the northeast Atlantic will exceed 0.4 m. In addition, wave-direction changes of around 20° per unit NAO index have been documented for one location. Such changes raise the possibility of consequential alteration of coastal erosion.

scholarly journals Future storm surge impacts on insurable losses for the North Sea region

2011 ◽  
Vol 11 (4) ◽  
pp. 1205-1216 ◽  
Author(s):  
L. Gaslikova ◽  
A. Schwerzmann ◽  
C. C. Raible ◽  
T. F. Stocker
Keyword(s):  
Sea Level ◽  
Storm Surge ◽  
North Sea ◽  
Sea Level Change ◽  
Coastal Protection ◽  
Sea Level Changes ◽  
Mean Sea Level ◽  
Level Change ◽  
The North ◽  
The North Sea

Abstract. The influence of climate change on storm surges including increased mean sea level change and the associated insurable losses are assessed for the North Sea basin. In doing so, the newly developed approach couples a dynamical storm surge model with a loss model. The key element of the approach is the generation of a probabilistic storm surge event set. Together with parametrizations of the inland propagation and the coastal protection failure probability this enables the estimation of annual expected losses. The sensitivity to the parametrizations is rather weak except when the assumption of high level of increased mean sea level change is made. Applying this approach to future scenarios shows a substantial increase of insurable losses with respect to the present day. Superimposing different mean sea level changes shows a nonlinear behavior at the country level, as the future storm surge changes are higher for Germany and Denmark. Thus, the study exhibits the necessity to assess the socio-economic impacts of coastal floods by combining the expected sea level rise with storm surge projections.

scholarly journals On sea level change in the North Sea influenced by the North Atlantic Oscillation: Local and remote steric effects

2014 ◽  
Vol 151 ◽  
pp. 186-195 ◽  
Author(s):  
Xinping Chen ◽  
Sönke Dangendorf ◽  
Nikesh Narayan ◽  
Kieran O'Driscoll ◽  
Michael N. Tsimplis ◽  
...  
Keyword(s):  
Sea Level ◽  
North Sea ◽  
North Atlantic ◽  
Sea Level Change ◽  
Steric Effects ◽  
Level Change ◽  
The North ◽  
The North Sea ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

Improving coastal altimetry results using the Spatio Temporal Altimetry Retracking for SAR (STARS)

2021 ◽  
Author(s):  
Bernd Uebbing ◽  
Christopher Buchhaupt ◽  
Sophie Stolzenberger ◽  
Luciana Fenoglio ◽  
Jürgen Kusche ◽  
...  
Keyword(s):  
Sea Level ◽  
Sea Level Change ◽  
Coastal Protection ◽  
Protection Measures ◽  
Processing Scheme ◽  
Level Change ◽  
The North ◽  
The North Sea ◽  
Spatio Temporal ◽  
Land Surfaces

&lt;p&gt;&lt;span&gt;A&lt;/span&gt;ccurate knowledge of sea level change, especially close to the coast, is of major importance in order to analyze &lt;span&gt;and&lt;/span&gt; understand drivers of local sea level change and to plan coastal protection measures. &lt;span&gt;S&lt;/span&gt;atellite altimetry provides a continuous global record of sea level rise since about 1993. In recent years, the delay doppler altimetry (DDA), also called SAR altimetry, provides improved results compared to conventional altimetry (CA) by utilizing the Doppler effect along the satellite&amp;#8217;s groundtrack.&lt;/p&gt;&lt;p&gt;The &lt;span&gt;altimeter emits&lt;/span&gt; a radar pulse from the satellite to the Earth&amp;#8217;s surface and measure the power reflected over time from the radar footprint forming a so called &amp;#8220;waveform&amp;#8221;. From the shift, shape and amplitude of this waveform it is possible to estimate sea surface height (SSH), significant waveheight (SWH) and backscatter which is related to wind speed. Due to influences from land surfaces within the radar footprint standard methods of retrieving those estimates tend to become &lt;span&gt;increasingly&lt;/span&gt; uncertain or even fail when the satellite groundtrack &lt;span&gt;approaches the coastline&lt;/span&gt;. In order to still derive meaningful geophysical parameters it is necessary to reprocess or &amp;#8220;retrack&amp;#8221; those waveforms with specialized algorithms resulting in improved estimates.&lt;/p&gt;&lt;p&gt;Here, we present a novel retracker which adapts the Spatio Temporal Altimetry Retracker (STARv1.0) processing scheme for CA to DDA. Generally, the STAR algorithm consists of three steps: (1) Partitioning of the total return waveform into individual sub-waveforms, (2) retracking of each individual sub-waveform resulting in a point-cloud of potential estimates of SSH, SWH and backscatter and (3) selection of final estimates at each 20Hz measurement position. For the application to DDA the three parameter &lt;span&gt;Brown model used in CA-STAR&lt;/span&gt; is replaced by the Signal model Involving Numerical Convolution for SAR (SINCS) model, already implemented in the Technical University Darmstadt &amp;#8211; University Bonn SAR-Reduced SAR (TUDaBo SAR-RDSAR) processing scheme.&lt;/p&gt;&lt;p&gt;&lt;span&gt;T&lt;/span&gt;he combination of the updated STARv2.5 processing scheme with the SINCS &lt;span&gt;model&lt;/span&gt; (STARS) allows to &lt;span&gt;retrieve&lt;/span&gt; high quality sea level estimates for contemporary DDA altimeter missions. We will &lt;span&gt;provide&lt;/span&gt; validation results for Cryosat-2 and Sentinel-3 data in the North Sea region &lt;span&gt;for the &lt;/span&gt;&lt;span&gt;time&lt;/span&gt;&lt;span&gt; period&lt;/span&gt; 2016-2019. Our preliminary results suggest that we are able to derive significantly improved results for SSH, SWH and backscatter from STARS compared to existing state of the art approaches &lt;span&gt;for &lt;/span&gt;DDA. While originally developed for coastal regions, the STAR processing scheme also leads to improved open ocean results.&lt;/p&gt;

What can idealized storm surge simulations tell us about worst case scenarios?

2021 ◽  
Author(s):  
Elin Andrée ◽  
Jian Su ◽  
Martin Drews ◽  
Morten Andreas Dahl Larsen ◽  
Asger Bendix Hansen ◽  
...  
Keyword(s):  
Wind Speed ◽  
Sea Level ◽  
North Sea ◽  
Wind Direction ◽  
Water Levels ◽  
Sea Levels ◽  
The North ◽  
The North Sea ◽  
Sea Coast ◽  
North Sea Coast

&lt;p&gt;The potential impacts of extreme sea level events are becoming more apparent to the public and policy makers alike. As the magnitude of these events are expected to increase due to climate change, and increased coastal urbanization results in ever increasing stakes in the coastal zones, the need for risk assessments is growing too.&lt;/p&gt;&lt;p&gt;The physical conditions that generate extreme sea levels are highly dependent on site specific conditions, such as bathymetry, tidal regime, wind fetch and the shape of the coastline. For a low-lying country like Denmark, which consists of a peninsula and islands that partition off the semi-enclosed Baltic Sea from the North Sea, a better understanding of how the local sea level responds to wind forcing is urgently called for.&lt;/p&gt;&lt;p&gt;We here present a map for Denmark that shows the most efficient wind directions for generating extreme sea levels, for a total of 70 locations distributed all over the country&amp;#8217;s coastlines. The maps are produced by conducting simulations with a high resolution, 3D-ocean model, which is used for operational storm surge modelling at the Danish Meteorological Institute. We force the model with idealized wind fields that maintain a fixed wind speed and wind direction over the entire model domain. Simulations are conducted for one wind speed and one wind direction at a time, generating ensembles of a set of wind directions for a fixed wind speed, as well as a set of wind speeds for a fixed wind direction, respectively.&lt;/p&gt;&lt;p&gt;For each wind direction, we find that the maximum water level at a given location increases linearly with the wind speed, and the slope values show clear spatial patterns, for example distinguishing the Danish southern North Sea coast from the central or northern North Sea Coast. The slope values are highest along the southwestern North Sea coast, where the passage of North Atlantic low pressure systems over the shallow North Sea, as well as the large tidal range, result in a much larger range of variability than in the more sheltered Inner Danish Waters. However, in our simulations the large fetch of the Baltic Sea, in combination with the funneling effect of the Danish Straits, result in almost as high water levels as along the North Sea coast.&lt;/p&gt;&lt;p&gt;Although the wind forcing is completely synthetic with no spatial and temporal structure of a real storm, this idealized approach allows us to systematically investigate the sea level response at the boundaries of what is physically plausible. We evaluate the results from these simulations by comparison to peak water levels from a 58 year long, high resolution ocean hindcast, with promising agreement.&lt;/p&gt;

scholarly journals Mean sea level variability in the North Sea: Processes and implications

2014 ◽  
Vol 119 (10) ◽  
pp. n/a-n/a ◽  
Author(s):  
Sönke Dangendorf ◽  
Francisco M. Calafat ◽  
Arne Arns ◽  
Thomas Wahl ◽  
Ivan D. Haigh ◽  
...  
Keyword(s):  
Sea Level ◽  
North Sea ◽  
Sea Level Variability ◽  
Mean Sea Level ◽  
The North ◽  
The North Sea ◽  
Mean Sea Level Variability

Searching for Factors that Limit Observed Extreme Maximum Wave Height Distributions in the North Sea

2008 ◽  
pp. 127-138 ◽  
Author(s):  
Gerrit Burgers ◽  
Frits Koek ◽  
Hans de Vries ◽  
Martin Stam
Keyword(s):  
Wave Height ◽  
North Sea ◽  
Maximum Wave Height ◽  
The North ◽  
The North Sea

Storm surges in the North Sea during the winter 1953-4

1956 ◽  
Vol 235 (1201) ◽  
pp. 260-274 ◽  
Keyword(s):  
Sea Level ◽  
North Sea ◽  
Storm Surges ◽  
Rate Of Change ◽  
The North ◽  
Order Of Magnitude ◽  
The North Sea ◽  
Sea Ports ◽  
Phase Angles

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.

scholarly journals Large-scale forcing of the European Slope Current and associated inflows to the North Sea

Ocean Science ◽  
2017 ◽  
Vol 13 (2) ◽  
pp. 315-335 ◽  
Author(s):  
Robert Marsh ◽  
Ivan D. Haigh ◽  
Stuart A. Cunningham ◽  
Mark E. Inall ◽  
Marie Porter ◽  
...  
Keyword(s):  
Sea Level ◽  
North Sea ◽  
Tide Gauge ◽  
Density Gradients ◽  
Current Transport ◽  
Tide Gauge Records ◽  
The North ◽  
Wide Range ◽  
The North Sea ◽  
Northern North Sea

Abstract. The European Slope Current provides a shelf-edge conduit for Atlantic Water, a substantial fraction of which is destined for the northern North Sea, with implications for regional hydrography and ecosystems. Drifters drogued at 50 m in the European Slope Current at the Hebridean shelf break follow a wide range of pathways, indicating highly variable Atlantic inflow to the North Sea. Slope Current pathways, timescales and transports over 1988–2007 are further quantified in an eddy-resolving ocean model hindcast. Particle trajectories calculated with model currents indicate that Slope Current water is largely recruited from the eastern subpolar North Atlantic. Observations of absolute dynamic topography and climatological density support theoretical expectations that Slope Current transport is to first order associated with meridional density gradients in the eastern subpolar gyre, which support a geostrophic inflow towards the slope. In the model hindcast, Slope Current transport variability is dominated by abrupt 25–50 % reductions of these density gradients over 1996–1998. Concurrent changes in wind forcing, expressed in terms of density gradients, act in the same sense to reduce Slope Current transport. This indicates that coordinated regional changes of buoyancy and wind forcing acted together to reduce Slope Current transport during the 1990s. Particle trajectories further show that 10–40 % of Slope Current water is destined for the northern North Sea within 6 months of passing to the west of Scotland, with a general decline in this percentage over 1988–2007. Salinities in the Slope Current correspondingly decreased, evidenced in ocean analysis data. Further to the north, in the Atlantic Water conveyed by the Slope Current through the Faroe–Shetland Channel (FSC), salinity is observed to increase over this period while declining in the hindcast. The observed trend may have broadly compensated for a decline in the Atlantic inflow, limiting salinity changes in the northern North Sea during this period. Proxies for both Slope Current transport and Atlantic inflow to the North Sea are sought in sea level height differences across the FSC and between Shetland and the Scottish mainland (Wick). Variability of Slope Current transport on a wide range of timescales, from seasonal to multi-decadal, is implicit in sea level differences between Lerwick (Shetland) and Tórshavn (Faroes), in both tide gauge records from 1957 and a longer model hindcast spanning 1958–2012. Wick–Lerwick sea level differences in tide gauge records from 1965 indicate considerable decadal variability in the Fair Isle Current transport that dominates Atlantic inflow to the northwest North Sea, while sea level differences in the hindcast are dominated by strong seasonal variability. Uncertainties in the Wick tide gauge record limit confidence in this proxy.

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