scholarly journals Sea-level variations on the north and northwest coasts of Spain

2012 ◽  
Vol 69 (5) ◽  
pp. 720-727 ◽  
Author(s):  
María Jesús García ◽  
Elena Tel ◽  
Joaquín Molinero
Keyword(s):  
Sea Level ◽  
North Atlantic ◽  
Extreme Values ◽  
Mean Sea Level ◽  
Sea Levels ◽  
The North ◽  
Glacial Rebound ◽  
Sea Level Variations ◽  
The Mean ◽  
Range Of Variation

Abstract García, M. J., Tel, E., and Molinero, J. 2012. Sea-level variations on the north and northwest coasts of Spain. – ICES Journal of Marine Science, 69: 720–727. An exhaustive analysis of historical sea-level records at three stations located along the northern and northwestern Spanish coast has permitted a description of the mean sea-level trend over the past 67 years. The analysis also produced results on the type, amplitude, and propagation of tides, as well as on the range of variation in the sea level, extreme values, and return periods. Once corrected for the Post Glacial Rebound, the rise in the mean sea level was estimated at 2.38, 2.45, and 2.65 mm year−1 in Santander, A Coruña, and Vigo, respectively. The meteorological contribution is evaluated by the winter North Atlantic Oscillation index, producing a correlation of −0.658 with the empirical orthogonal function mode 1, which explained 81.86% of the total variance of winter (from December to March) mean sea levels. Harmonic analysis evidenced the semi-diurnal nature of the tide and showed that the amplitude and propagation of the M2 tidal wave followed the North Atlantic regional pattern, with decreasing amplitudes and phases from east to west. Hourly height levels were run through an extreme analysis and resulted in maximum sea-level values over the respective mean sea levels (datum): 2.55, 2.48, and 2.51 m in Santander, A Coruña, and Vigo, respectively. The estimated extreme levels for a 120-year return period exceeded the observed maxima in the three locations by 0.25, 015, and 0.10 m, respectively.

scholarly journals Variations in the difference between mean sea level measured either side of Cape Hatteras and their relation to the North Atlantic Oscillation

2016 ◽  
Vol 49 (7-8) ◽  
pp. 2451-2469 ◽  
Author(s):  
P. L. Woodworth ◽  
M. Á. Morales Maqueda ◽  
W. R. Gehrels ◽  
V. M. Roussenov ◽  
R. G. Williams ◽  
...  
Keyword(s):  
North Atlantic Oscillation ◽  
Sea Level ◽  
North Atlantic ◽  
Mean Sea Level ◽  
The North ◽  
Cape Hatteras ◽  
The North Atlantic ◽  
The Difference ◽  
The North Atlantic Oscillation

scholarly journals Sub-basin scale sea level budgets from satellite altimetry, Argo floats and satellite gravimetry in the North Atlantic

2016 ◽  
Author(s):  
Marcel Kleinherenbrink ◽  
Riccardo Riva ◽  
Yu Sun
Keyword(s):  
Time Series ◽  
Gravity Field ◽  
Sea Level ◽  
North Atlantic ◽  
Covariance Matrices ◽  
Sea Levels ◽  
The North ◽  
Basin Scale ◽  
Gravity Fields ◽  
The North Atlantic

Abstract. In this study for the first time an attempt is made to close the sea level budget on a sub-basin scale in terms of trend, annual amplitude and residual time series, after removing the trend, the semi-annual and annual signals. To obtain errors for altimetry and Argo full variance-covariance matrices are computed using correlation functions and their errors are fully propagated. For altimetry we apply a geographically dependent intermission bias (Ablain et al., 2015), which leads to differences in trends up to 0.8 mm yr−1. Since Argo float measurements are non-homogeneously spaced, steric sea levels are first objectively interpolated onto a grid before averaging. For the Gravity Recovery And Climate Experiment (GRACE) gravity fields full variance-covariance matrices are used to propagate errors and statistically filter the gravity fields. We use four different filtered gravity field solutions and determine which post-processing strategy is best for budget closure. As a reference the standard 96-degree DDK5-filtered CSR solution is used to compute OBP. A comparison is made with two anistropic Wiener-filtered CSR solutions up to d/o 60 and 96 and a Wiener-filtered 90-degree ITSG solution. Budgets are computed for ten polygons in the North Atlantic, defined in a way that the error on the trend of Ocean Bottom Pressure (OBP) + steric sea level remains within 1 mm yr−1. Using the anisotropic Wiener filter on CSR gravity fields expanded up to spherical harmonic degree 96, it is possible to close the sea level budget in nine-out-of-ten sub-basins in terms of trend. Wiener-filtered ITSG and the standard DDK5-filtered CSR solutions also close the trend budget, if a Glacial Isostatic Adjustment (GIA) correction error of 10–20 % is applied, however the performance of the DDK5-filtered solution strongly depends on the orientation of the polygon due to residual striping. In seven-out-of-ten sub-basins the budget of the annual cycle is closed, using the DDK5-filtered CSR or the Wiener-filtered ITSG solutions.The Wiener-filtered 60- and 96-degree CSR solution in combination with Argo lack amplitude and suffer from what appears to be hydrological leakage in the Amazon and Sahel regions. After reducing the trend, semi-annual and annual signals, 24–53 % of the residual variance in altimetry-derived sea level time series is explained by the combination of Argo steric sea levels and Wiener-filtered ITSG OBP.Based on this, we believe that the best overall solution for the OBP component of the sub-basin scale budgets is the Wiener-filtered ITSG gravity fields. The interannual variability is primarily a steric signal in the North Atlantic, so for this the choice of filter and gravity field solution is not really significant.

scholarly journals Giant boulders and Last Interglacial storm intensity in the North Atlantic

2017 ◽  
Vol 114 (46) ◽  
pp. 12144-12149 ◽  
Author(s):  
Alessio Rovere ◽  
Elisa Casella ◽  
Daniel L. Harris ◽  
Thomas Lorscheid ◽  
Napayalage A. K. Nandasena ◽  
...  
Keyword(s):  
Sea Level ◽  
North Atlantic ◽  
Global Climate ◽  
Last Interglacial ◽  
The Bahamas ◽  
Sea Levels ◽  
Storm Intensity ◽  
The North ◽  
Rising Sea Levels ◽  
Mis 5E

As global climate warms and sea level rises, coastal areas will be subject to more frequent extreme flooding and hurricanes. Geologic evidence for extreme coastal storms during past warm periods has the potential to provide fundamental insights into their future intensity. Recent studies argue that during the Last Interglacial (MIS 5e, ∼128–116 ka) tropical and extratropical North Atlantic cyclones may have been more intense than at present, and may have produced waves larger than those observed historically. Such strong swells are inferred to have created a number of geologic features that can be observed today along the coastlines of Bermuda and the Bahamas. In this paper, we investigate the most iconic among these features: massive boulders atop a cliff in North Eleuthera, Bahamas. We combine geologic field surveys, wave models, and boulder transport equations to test the hypothesis that such boulders must have been emplaced by storms of greater-than-historical intensity. By contrast, our results suggest that with the higher relative sea level (RSL) estimated for the Bahamas during MIS 5e, boulders of this size could have been transported by waves generated by storms of historical intensity. Thus, while the megaboulders of Eleuthera cannot be used as geologic proof for past “superstorms,” they do show that with rising sea levels, cliffs and coastal barriers will be subject to significantly greater erosional energy, even without changes in storm intensity.

Coastal inundation hazard in the North Adriatic Sea under Climate Change

2020 ◽  
Author(s):  
Arthur Hrast Essenfelder ◽  
Mattia Amadio ◽  
Stefano Bagli ◽  
Paolo Mazzoli
Keyword(s):  
Sea Level ◽  
Adriatic Sea ◽  
Coastal Flooding ◽  
Short Term ◽  
Coastal Inundation ◽  
Mean Sea Level ◽  
Sea Levels ◽  
The North ◽  
Extreme Sea Levels ◽  
North Adriatic Sea

<p>On the 12<sup>th</sup> of November of 2019, flood levels in the Venice Lagoon have reached the mark of 1.87 metres, the second-highest level since records began in 1923. Although a recurrent problem in Venice, the significance of this event have raise awareness of the issue of coastal inundation hazard in Italy, particularly at the highly vulnerable territory of the regions facing the North Adriatic Sea. Several are the processes that contribute to a costal inundation event. On the short term, processes such as high tide and storm surge events can result in sea levels, potentially triggering devastating impacts on human settlements and activities. On the long term, the land subsidence and mean sea level (MSL) changes are important factors; in fact, in some regions such as Jakarta and Bangkok the land is expected to subside by more than 1 meter, while MSL is expected to rise during the next decades, reaching global mean absolute values ranging from 0.3–0.6m (RCP 2.6) to 0.5–1.1m (RCP 8.5) by the end of the century. The combined effect of global sea level rise, local subsidence, and short term phenomena can potentially increase the frequency and intensity of extreme sea levels (ESL), posing a major threat to coastal areas. Currently, almost 700 million people live in low-lying coastal areas, and about 13% of them are exposed to a 100-year flood. In Italy, a territory that is highly vulnerable to coastal flooding are the Regions facing the North Adriatic Sea, mainly due to two factors: the morphological characteristic of this territory, characterised by low-lying areas, and the bathymetry and shape of the Adriatic basin, which cause water level to accumulate and increase rapidly during storm surge events, especially during winter. In this paper, we evaluate two different coastal inundation modelling techniques, one hydrostatic (as part of the EIT Climate-KIC SaferPLACES project) and another hydrodynamic (the ANUGA model), by stressing the models with different ESL, both for the historical mean sea level and for MSL projections at 2050 and 2100. The two different inundation models are tested on three pilot sites particularly vulnerable to coastal flooding located in the North Adriatic Sea: Venice, Cesenatico, and Rimini. We compare our modelling results with existing hazard records and previous hazard and risk assessments. Finally, we apply a flood damage model developed for Italy to estimate the potential economic damages linked to the different flood scenarios, and we calculate the change in expected annual damages according to the relative extreme sea levels.</p>

scholarly journals Analysis on the Extreme Sea Levels Changes along the Coastline of Bohai Sea, China

Atmosphere ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 324 ◽  
Author(s):  
Jianlong Feng ◽  
Delei Li ◽  
Hui Wang ◽  
Qiulin Liu ◽  
Jianli Zhang ◽  
...  
Keyword(s):  
Sea Level ◽  
Bohai Sea ◽  
High Tide ◽  
Tide Gauges ◽  
Mean Sea Level ◽  
Sea Levels ◽  
The Bohai Sea ◽  
Extreme Sea Levels ◽  
The Mean

Using hourly sea level data from four tide gauges, the changes of the extreme sea level in the Bohai Sea were analyzed in this work. Three components (i.e., mean sea level, tide and surge) as well as the tide–surge interaction were studied to find which component was important in the changes of extreme sea levels. Significant increasing trends exist in the mean sea level at four tide gauges from 1980 to 2016, and the increase rate ranges from 0.2 to 0.5 cm/year. The mean high tide levels show positive trends at four tide gauges, and the increasing rate (0.1 to 0.3 cm/year) is not small compared with the long-term trends of the mean sea levels. However, the mean tidal ranges show negative trends at Longkou, Qinhuangdao and Tanggu, with the rate from about −0.7 to −0.2 cm/year. At Qinhuangdao and Tanggu, the annual surge intensity shows explicit long-term decreasing trend. At all four tide gauges, the storm surge intensity shows distinct inter-annual variability and decadal variability. All four tide gauges show significant tide–surge interaction, the characteristics of the tide–surge interaction differ due to their locations, and no clear long-term change was found. Convincing evidence implies that the extreme sea levels increase during the past decades from 1980 to 2016 at all tide gauges, with the increasing rate differing at different percentile levels. The extreme sea level changes in the Bohai Sea are highly affected by the changes of mean sea level and high tide level, especially the latter. The surge variation contributes to the changes of extreme sea level at locations where the tide–surge interaction is relatively weak.

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