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1.
Anette Ganske Natacha Fery Lidia Gaslikova Iris Grabemann Ralf Weisse Birger Tinz 《Ocean Dynamics》2018,68(10):1371-1382
Planning and design of coastal protection rely on information about the probabilities of very severe storm tides and the possible changes that may occur in the course of climate change. So far, this information is mostly provided in the form of high percentiles obtained from frequency distributions or return values. More detailed information and assessments of events that may cause extreme damages or have extreme consequences at the coast are so far still unavailable. We describe and compare two different approaches that may be used to identify highly unlikely but still physically possible and plausible events from model simulations. Firstly, in the case when consistent wind and tide-surge data are available, different metrics such as the height of the storm surge can be derived directly from the simulated water levels. Secondly, in cases where only atmospheric data are available, the so called effective wind may be used. The latter is the projection of the horizontal wind vector on that direction which is most effective in producing surges at the coast. Comparison of events identified by both methods show that they can identify extreme events but that knowledge of the effective wind alone does not provide sufficient information to identify the highest storm surges. Tracks of the low-pressure systems over the North Sea need to be investigated to find those cases, where the duration of the high wind is too short to induce extreme storm tides. On the other hand, factors such as external surges or variability in mean sea level may enhance surge heights and are not accounted for in estimates based on effective winds only. Results from the analysis of an extended data set suggest that unprecedented storm surges at the German North Sea coast are possible even without taking effects from rising mean sea level into account. The work presented is part of the ongoing project “Extreme North Sea Storm Surges and Their Consequences” (EXTREMENESS) and represents the first step towards an impact assessment for very severe storm surges which will serve as a basis for development of adaptation options and evaluation criteria. 相似文献
2.
The coastal zones are facing the prospect of changing storm surge statistics due to anthropogenic climate change. In the present study, we examine these prospects for the North Sea based on numerical modelling. The main tool is the barotropic tide-surge model TRIMGEO (Tidal Residual and Intertidal Mudflat Model) to derive storm surge climate and extremes from atmospheric conditions. The analysis is carried out by using an ensemble of four 30-year atmospheric regional simulations under present-day and possible future-enhanced greenhouse gas conditions. The atmospheric regional simulations were prepared within the EU project PRUDENCE (Prediction of Regional scenarios and Uncertainties for Defining EuropeaN Climate change risks and Effects). The research strategy of PRUDENCE is to compare simulations of different regional models driven by the same global control and climate change simulations. These global conditions, representative for 1961–1990 and 2071–2100 were prepared by the Hadley Center based on the IPCC A2 SRES scenario. The results suggest that under future climatic conditions, storm surge extremes may increase along the North Sea coast towards the end of this century. Based on a comparison between the results of the different ensemble members as well as on the variability estimated from a high-resolution storm surge reconstruction of the recent decades it is found that this increase is significantly different from zero at the 95% confidence level for most of the North Sea coast. An exception represents the East coast of the UK which is not affected by this increase of storm surge extremes. 相似文献
3.
The 1953 North Sea floods, the Big Flood, was one of the worst natural disasters in Europe in modern times and is probably one of the most studied severe coastal floods. Several factors led to the devastating storm surge along the southern North Sea coast in combination of strong and sustained northerly winds, invert barometric effect, high spring tide, and an accumulation of the large surge in the Strait of Dover. However, the storm waves and their roles during the 1953 North Sea storm surge are not well investigated. Therefore, the effect of wave setup due to breaking waves in the storm surge processes is investigated through numerical experiments. A coupled process-based tide-wave-surge model was used to investigate and simulate the storm surge in the North Sea during January 31–February 1, 1953 and validated by comparing with historical water level records at tide gauges and wave observations at light vessels in the North Sea. Meteorological forcing inputs for the period, January 27–February 3, 1953 are reproduced from ERA-20C reanalysis data with a constant correction factor for winds. From the simulation results, it is found that, in addition to the high water due to wind setup, wave setup due to breaking waves nearshore play a role of approximately 10% of the storm surge peaks with approximately 0.2 m. The resulting modeling system can be used extensively for the preparedness of the storm surge and wave of extreme condition, and usual barotropic forecast. 相似文献
4.
The storm surge period of 13–16 November 1977 when there was a major positive surge followed by a negative surge in the Irish
Sea is investigated using a two-dimensional unstructured mesh model of the west coast of Britain. The model accounts for tidal
and external surge forcing across its open boundaries which are situated in the Celtic Sea and off the west coast of Scotland.
Although this period has been examined previously using a uniform finite-difference model, and a finite element model, neither
of these could resolve the Mersey estuary which is the focus of the present study. By using a finite element model with very
high mesh resolution within the Mersey, the spatial variability of surge elevations and currents within the Mersey to rapidly
changing surge dynamics can be examined. The mesh in the model varies from about 7 km in deep water, to the order of 100 m
in the Mersey, with the largest mesh length reaching 17 km in deep offshore regions, and smallest of order 26 m occurring
in shallow coastal regions of the Mersey estuary. The model accounts for wetting/drying which occurs in shallow water coastal
areas. Calculations showed that during the positive surge period, the amplitude and speed of propagation of the surge was
largest in the deep water channels. This gave rise to significant spatial variability of surge elevations and currents within
the estuary. As wind stresses decreased over the Irish Sea, a negative surge occurred over Liverpool Bay and at the entrance
to the Mersey. However, within the Mersey there was a local positive surge which continued to propagate down the estuary.
This clearly showed that although the large scale response of the Irish Sea to changing wind fields occurred rapidly, the
response in the Mersey was much slower. These calculations with a west coast variable mesh model that included a high-resolution
representation of the Mersey revealed for the first time how elevations and currents within the Mersey responded to Irish
Sea surges that rapidly changed from positive to negative. 相似文献
5.
《Continental Shelf Research》2007,27(10-11):1548-1567
A two-way nested coupled tide-surge prediction model was established and applied in the Taiwan Strait and adjacent sea area in this study. This two-dimensional (2D) model had a fine horizontal resolution and took into account the interaction between storm surges and astronomical tides, which made it suitable for depicting the complicated physical properties of storm surges in the Taiwan Strait. A two-way nesting technique and an open boundary condition developed from Flather's radiation condition and Røed and Smedstad's local mode idea, were successfully implemented in the model. A simulation experiment showed that the open boundary condition could be used in the coupled tide-surge model and that the performance of the two-way nested model was slightly superior in accuracy to that of the one-way nested one.The fluctuations of storm surge residuals with tidal period at Sansha and Pingtan tide stations during the period of typhoon Dan in 1999 were well reproduced by the model, with the coupling effect between storm surges and tides indicating that the effect of astronomical tides upon typhoon surges should be considered in a storm-surge prediction model for the Taiwan Strait. The forecast experiment during typhoon Talim in 2005 showed that the storm surge prediction outputs by the model were better in the early 20 h of the forecast period of each model run than those in the later period due to the prediction accuracy of the typhoon track, maximum winds, and central air pressures. 相似文献
6.
7.
Amplification of the storm surges in shallow waters of the Pertuis Charentais (Bay of Biscay,France) 总被引：1，自引：1，他引：0
The Pertuis Charentais are shallow coastal embayments formed by the islands of Oleron and Re in the north-eastern Bay of Biscay.
The low-lying coasts of the Pertuis Charentais are susceptible to extensive flooding caused by the storm surges generated
in the North Atlantic. Numerical modelling of the 24 October 1999 surge event is performed in the present study in order to
elucidate the impact of the wind-wave-tide-surge interactions on the surge propagation in the Pertuis Charentais. A 2D numerical
model is constructed to simulate the wave and tide-surge propagation on a high-resolution finite-element grid by using the
TELEMAC and TOMAWAC software. The effect of the wave-induced enhancement on the sea surface drag and on the bottom friction
is evaluated by using the models of Janssen (1991) and Christoffersen and Jonsson (1985), respectively. The radiation stress is estimated by employing the approach of Longuet-Higgins and Stewart (1964). It is demonstrated that the peak surge in the night on 23–24 October has been amplified inside the Pertuis Charentais by
about 20 cm due to the wind-wave interactions with the tide-surge currents. These interactions are strongest at the entrance
to the Pertuis Charentais where the sea surface drag coefficient is significantly increased by the wind-wave coupling. The
effect of the wave-tide-surge interactions is large enough to be included in the flood forecasting systems of this region. 相似文献
8.
An unstructured grid storm surge model of the west coast of Britain, incorporating a high-resolution representation of the
Mersey estuary is used to examine storm surge dynamics in the region. The focus of the study is the major surge that occurred
during the period 11–14 November 1977, which has been investigated previously using uniform grid finite difference models
and a finite element model of the west coast of Britain. However, none of these models included the Mersey estuary. Comparison
of solutions in the eastern Irish Sea with those computed with these earlier models showed that, away from the Liverpool Bay
region, the inclusion of the Mersey estuary had little effect. However, at the entrance to the Mersey, its inclusion did influence
the solution. By including a detailed representation of the Mersey estuary within the model, it was possible to conduct a
detailed study of storm surge propagation in the Mersey, which had never previously been performed. This detailed study showed
for the first time that the surge’s temporal variability within the estuary is influenced by surge elevation at its entrance.
This varies with time as a function of spatial and temporal variations of wind stress over the west coast of Britain. Within
the Mersey, calculations show that the spatial variability is mainly determined by changes in bottom topography, which had
not been included in earlier finite difference models. However, since water depth is influenced by variations in tidal elevation,
this, together with tide surge interaction through bottom friction and momentum advection, influences the surge. The ability
of the finite element model to vary the mesh in near-shore regions to such an extent that it can resolve the Mersey and hence
the impact of the Mersey estuary upon the Liverpool Bay circulation shows that it has distinct advantages over earlier finite
difference models. In the absence of detailed measurements within the Mersey at the time of the surge, it was not possible
to validate predicted surge elevations within the Mersey. However, significant insight into physical processes influencing
the surge propagation down the estuary, its reflection and spatial/temporal variability could be gained. 相似文献
9.
Agnieszka Indiana Olbert Stephen Nash Conleth Cunnane Michael Hartnett 《Ocean Dynamics》2013,63(6):599-614
The research presented in this paper involves the application of the joint probability method to the estimation of extreme water levels resulting from astronomical tides and surge residuals and the investigation of the effects of tide–surge interactions on extreme water levels. The distribution of tide peaks was analysed from field records (<20 years) and a 46-year dataset of monthly maximum tidal amplitudes. Large surges were extracted from both field records and a numerical model hindcast covering the 48 largest storm events in the Irish Sea over the period 1959–2005. Extreme storm surges and tides were independently modelled using the generalised extreme value statistical model, and derived probability distributions were used to compute extreme water levels. An important, and novel, aspect of this research is an analysis of tide–surge interactions and their effects on total water level; where interactions exist, they lead to lower total water levels than in the case of independency. The degree of decrease varies with interaction strength, magnitude of surge peak at a particular phase of tide and the distribution of peaks over a tidal cycle. Therefore, including interactions in the computation of extreme levels may provide very useful information at the design stage of coastal protection systems. 相似文献
10.
Joanna Staneva Victor Alari Øyvind Breivik Jean-Raymond Bidlot Kristian Mogensen 《Ocean Dynamics》2017,67(1):81-101
The effect of wind waves on water level and currents during two storms in the North Sea is investigated using a high-resolution Nucleus for European Modelling of the Ocean (NEMO) model forced with fluxes and fields from a high-resolution wave model. The additional terms accounting for wave-current interaction that are considered in this study are the Stokes-Coriolis force, the sea-state-dependent energy and momentum fluxes. The individual and collective role of these processes is quantified and the results are compared with a control run without wave effects as well as against current and water-level measurements from coastal stations. We find a better agreement with observations when the circulation model is forced by sea-state-dependent fluxes, especially in extreme events. The two extreme events, the storm Christian (25–27 October 2013), and about a month later, the storm Xaver (5–7 December 2013), induce different wave and surge conditions over the North Sea. Including the wave effects in the circulation model for the storm Xaver raises the modelled surge by more than 40 cm compared with the control run in the German Bight area. For the storm Christian, a difference of 20–30 cm in the surge level between the wave-forced and the stand-alone ocean model is found over the whole southern part of the North Sea. Moreover, the modelled vertical velocity profile fits the observations very well when the wave forcing is accounted for. The contribution of wave-induced forcing has been quantified indicating that this represents an important mechanism for improving water-level and current predictions. 相似文献
11.
12.
Numerical modeling of storm surges in the coast of Mozambique: the cases of tropical cyclones Bonita (1996) and Lisette (1997) 总被引：1，自引：1，他引：0
Alberto José Bié Ricardo de Camargo Alberto Francisco Mavume Joseph Harari 《Ocean Dynamics》2017,67(11):1443-1459
The coast of Mozambique is often affected by storms, particularly tropical cyclones during summer or sometimes midlatitude systems in the southern part. Storm surges combined with high freshwater discharge can drive huge coastal floods, affecting both urban and rural areas. To improve the knowledge about the impact of storm surges in the coast of Mozambique, this study presents the first attempt to model this phenomenon through the implementation of the Princeton Ocean Model (POM) in the Southwestern Indian Ocean domain (SWIO; 2–32°S, 28–85°E) using a regular grid with 1/6° of spatial resolution and 36 sigma levels. The simulation was performed for the period 1979–2010, and the most interesting events of surges were related to tropical cyclones Bonita (1996) and Lisette (1997) that occurred in the Mozambique Channel. The results showed that the model represented well the amplitude and phase of principal lunar and solar tidal constituents, as well as it captured the spatial pattern and magnitudes of SST with slight positive bias in summer and negative bias in winter months. In terms of SSH, the model underestimated the presence of mesoscale eddies, mainly in the Mozambique Channel. Our results also showed that the atmospheric sea level pressure had a significant contribution to storm heights during the landfall of the tropical cyclones Bonita (1996) and Lisette (1997) in the coast of Mozambique contributing with about 20 and 16% of the total surge height for each case, respectively, surpassing the contribution of the tide-surge nonlinear interactions by a factor of 2. 相似文献
13.
Numerical study of the barotropic responses to a rapidly moving typhoon in the East China Sea 总被引：2，自引：1，他引：1
Yang Ding Huaming Yu Xianwen Bao Liang Kuang Caixia Wang Wenjuan Wang 《Ocean Dynamics》2011,61(9):1237-1259
Barotropic responses of the East China Sea to typhoon KOMPASU are investigated using a high-resolution, three-dimensional,
primitive equation, and finite volume coastal ocean model. Even the fact that the typhoon KOMPASU only brushed across the
brink of China mainland without landing, it still imposed great influence across China's east coastal area, where storm surges
ranging from 35 to 70 cm were intrigued during this event and a large wake of water setdown due to the outward radial transport
driven by the cyclonic wind stress was generated after the KOMPASU traveled across the Yellow Sea. Analysis of the numerical
results reveals that the barotropic waves propagating along the coast after the typhoon's landing can be identified as Kelvin
wave and the currents associated with the storm are geostrophic currents. A series of model runs are initiated to diagnose
the effects of wind stress, atmospheric pressure, and storm track variation on the surge's spatial distribution in the East
China Sea. The barotropic waves affected by the atmospheric disturbance due to the typhoon in deep Pacific Ocean travel far
more rapidly, arriving at the coastal regions at least 60 h ahead of the typhoon. The wave amplitudes are merely 0.2–0.4 cm
and damp gradually due to friction. The model experiments also confirm that the surge levels in nearshore regions are highly
dominated by winds, whereas the water level variations in deeper areas are controlled by the atmospheric pressure forcing
during typhoon events in the East China Sea. 相似文献
14.
The aim of this study is to investigate tide–surge interaction in narrow channels with complex and relatively shallow topography. A high-resolution depth-integrated tidal and storm surge model has been implemented for the Tjeldsund channel which is an important sailing lane in northern Norway. A horizontal grid resolution down to 50 m is applied in order to represent the complex bottom topography and the formation of jets and small-scale eddies. Two typically storm surge events in December 2004 have been examined in detail. The tide–surge interaction is found to influence the generation of higher harmonics and the formation of eddies in the current field. In some cases, the magnitude of storm surge currents may reach the same magnitude as the tidal currents enhancing the formation of jets and eddies. 相似文献
15.
Koen R. G. Reef Giordano Lipari Pieter C. Roos Suzanne J. M. H. Hulscher 《Ocean Dynamics》2018,68(8):1051-1065
We present an idealized network model for storm surges in the Wadden Sea, specifically including a time-dependent wind forcing (wind speed and direction). This extends the classical work by H.A. Lorentz who only considered the equilibrium response to a steady wind forcing. The solutions obtained in the frequency domain for the linearized shallow-water equations in a channel are combined in an algebraic system for the network. The velocity scale that is used for the linearized friction coefficient is determined iteratively. The hindcast of the storm surge of 5 December 2013 produces credible time-varying results. The effects of storm and basin parameters on the peak surge elevation are the subject of a sensitivity analysis. The formulation in the frequency domain reveals which modes in the external forcing lead to the largest surge response at coastal stations. There appears to be a minimum storm duration, of about 3–4 h, that is required for a surge to attain its maximum elevation. The influence of the water levels at the North Sea inlets on the Wadden Sea surges decreases towards the shore. In contrast, the wind shearing generates its largest response near the shore, where the fetch length is at its maximum. 相似文献
16.
Perturbation of regional ocean tides due to coastal dikes 总被引：1，自引：0，他引：1
The tidal regime modeling system for ocean tides in the seas bordering the Korean Peninsula is designed to cover an area that is broad in scope and size, yet provide a high degree of resolution in coastal development areas, including the Saemangeum area in the eastern Yellow Sea and the Ariake Sea in Japan, where serious environmental problems have occurred after the completion of interior tidal dikes. With this simulation system, we have estimated the changes in tidal regime due to barriers at Saemangeum and Isahaya Bay in the Ariake Sea. Some results in terms of perturbations in tidal elevations due to the construction of coastal dikes are presented and discussed. 相似文献
17.
Rainer Reuter Thomas H. Badewien Alexander Bartholomä Axel Braun Andrea Lübben Jürgen Rullkötter 《Ocean Dynamics》2009,59(2):195-211
In the tidal inlet between the East Frisian islands of Langeoog and Spiekeroog, southern North Sea, a time-series station
was set up in autumn 2002 as part of the research programme BioGeoChemistry of Tidal Flats run by the University of Oldenburg. The purpose of the station is to provide continuous data on physical, biological and
chemical parameters. In addition to instruments recording basic hydrographic and meteorological parameters, the time-series
station is equipped with acoustic Doppler profilers for measuring surface waves and current profiles. Compact optical spectrometers
are being used for spectral measurements of seawater transmission and for daylight reflectance. Additional sensors were installed
for measuring oxygen, nutrients and methane in the seawater. The data shall help to quantify the flux of dissolved and suspended
matter between the backbarrier tidal flat and the open sea and to characterise the material transformation in the tidal flat
area by biogeochemical processes over the tidal cycle. Due to its novel design, operation of the station is also possible
during winter and under extreme weather conditions (gales, storm surges, and sea ice) when data sampling with conventional
platforms such as research vessels, buoys, or smaller poles could not be performed in the past. In this way, time series of
data are obtained, which include events that are most relevant to the evolution of this coastal area. The performance of the
station and its equipment are presented with data covering 6 years of operation. Time series of air and water temperature
as well as seawater salinity demonstrate the multiyear dynamics of these parameters in the East Frisian Wadden Sea. Hydrographic
data collected under specific meteorological conditions such as gales and storm surges exemplify the all-weather capabilities
of the station and its value for studying hydrographic processes in the Wadden Sea. 相似文献
18.
The effectiveness of simulating surge inundation using the Eulerian–Lagrangian circulation (ELCIRC) model over multi-scale
unstructured grids was examined in this study. The large domain model grid encompasses the western North Atlantic Ocean, the
Gulf of Mexico, and the Caribbean Sea to appropriately account for remote and resonance effects during hurricane events and
simplify the specification of the open boundary condition. The U.S. East and Gulf Coasts were divided into 12 overlapping
basins with fine-resolution (up to 30 × 30 m) grids to model overland surge flooding. These overlapping basins have different
fine-resolution grids near the coastal region, but have an identical coarse-resolution grid in the offshore region within
the large model domain. Thus, the storm surge prediction can be conducted without reducing computation efficiency by executing
multiple model runs with local fine-resolution grids where potential hurricane landfalls may occur. The capability of the
multi-scale approach was examined by simulating storm surge caused by Hurricanes Andrew (1992) and Isabel (2003) along the
South Florida coast and in the Chesapeake Bay. Comparisons between simulated and observed results suggest that multi-scale
models proficiently simulated storm surges in the Biscayne Bay and the Chesapeake Bay during two hurricanes. A series of sensitivity
tests demonstrated that the simulation of surge flooding was improved when LiDAR topographic data and special bottom drag
coefficient values for mangrove forests were employed. The tests also showed that appropriate representation of linear hydrologic
features is important for computing surge inundation in an urban area. 相似文献
19.
The influence of a summer storm event in 2007 on the North Sea and its effects on the ocean stratification are investigated using a regional coupled ocean (Regional Ocean Modeling System, ROMS)-atmosphere (Weather Research & Forecasting model, WRF) modeling system. An analysis of potential energy anomaly (PEA, Φ) and its temporal development reveals that the loss of stratification due to the storm event is dominated by vertical mixing in almost the entire North Sea. For specific regions, however, a considerable contribution of depth-mean straining is observed. Vertical mixing is highly correlated with wind induced surface stresses. However, peak mixing values are observed in combination with incoming flood currents. Depending on the phase between winds and tides, the loss of stratification differs strongly over the North Sea. To study the effects of interactive ocean-atmosphere exchange, a fully coupled simulation is compared with two uncoupled ones for the same vertical mixing parameters to identify the impact of spatial resolution as well as of SST feedback. While the resulting new mixed layer depth after the storm event in the uncoupled simulation with lower spatial and temporal resolution of the surface forcing data can still be located in the euphotic zone, the coupled simulation is capable to mix the entire water column and the vertical mixing in the uncoupled simulation with higher resolution of the surface forcing data is strongly amplified. These differences might have notable implications for ecosystem modeling since it could determine the development of new phytoplankton blooms after the storm and for sediment modeling in terms of sediment mobilization. An investigation of restratification after the extreme event illustrates the persistent effect of this summer storm. 相似文献
20.
This work deals with the analysis of simulations carried out with a primitive equation numerical model for the region of the
East Frisian Wadden Sea. The model, with 200-m resolution, is forced by wind, air–sea heat, and water fluxes and river runoff
and is nested in a German Bight 1-km-resolution numerical model, the latter providing tidal forcing for the fine resolution
model. The analysis of numerical simulations is focused both on responses due to moderate conditions, as well as to extreme
events, such as the storm surge Britta, for which the model demonstrates very good skills. The question addressed in this
paper is how well the model output can be compressed with the help of empirical orthogonal function analysis. It is demonstrated
that, for the short-time periods of the order of a spring–neap cycle, only a few modes are necessary to almost fully represent
the circulation. This is just an illustration that the circulation in this region is subject to the dominating tidal forcing,
creating clear and relatively simple response patterns. However, for longer periods of about several months, wind forcing
is also very important, and correspondingly, the circulation patterns become much more complex. Possible applications of the
results in hindcasting and forecasting of hydrodynamics and sediment dynamics in the coastal zone are considered. 相似文献