Wind-Driven Coastal Sea Level Variability in the Northeast Pacific

Abstract The rate of coastal sea level change in the northeast Pacific (NEP) has decreased in recent decades. The relative contributions to the decreased rate from remote equatorial wind stress, local longshore wind stress, and local windstress curl are examined. Regressions of sea level onto wind stress time series and comparisons between NEP and Fremantle sea levels suggest that the decreased rate in the NEP is primarily due to oceanic adjustment to strengthened trade winds along the equatorial and coastal waveguides. When taking care to account for correlations between the various wind stress time series, the roles of longshore wind stress and local windstress curl are found to be of minor importance in comparison to equatorial forcing. The predictability of decadal sea level change rates along the NEP coastline is therefore largely determined by tropical variability. In addition, the importance of accounting for regional, wind-driven sea level variations when attempting to calculate accelerations in the long-term rate of sea level rise is demonstrated.

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The Effect of Wind Stress on Seasonal Sea-Level Change on the Northwestern European Shelf

Journal of Climate ◽

10.1175/jcli-d-21-0636.1 ◽

2022 ◽

pp. 1-31

Keyword(s):

Sea Level ◽

Wind Stress ◽

Sea Level Change ◽

Ocean Model ◽

Seasonal Differences ◽

Sea Levels ◽

Level Change ◽

Stress Changes ◽

European Shelf ◽

Emissions Scenario

Abstract Projections of relative sea-level change (RSLC) are commonly reported at an annual mean basis. The seasonality of RSLC is often not considered, even though it may modulate the impacts of annual mean RSLC. Here, we study seasonal differences in 21st-century ocean dynamic sea-level change (DSLC, 2081-2100 minus 1995-2014) on the Northwestern European Shelf (NWES) and their drivers, using an ensemble of 33 CMIP6 models complemented with experiments performed with a regional ocean model. For the high-end emissions scenario SSP5-8.5, we find substantial seasonal differences in ensemble mean DSLC, especially in the southeastern North Sea. For example, at Esbjerg (Denmark), winter mean DSLC is on average 8.4 cm higher than summer mean DSLC. Along all coasts on the NWES, DSLC is higher in winter and spring than in summer and autumn. For the low-end emissions scenario SSP1-2.6, these seasonal differences are smaller. Our experiments indicate that the changes in winter and summer sea-level anomalies are mainly driven by regional changes in wind-stress anomalies, which are generally southwesterly and east-northeasterly over the NWES, respectively. In spring and autumn, regional wind-stress changes play a smaller role. We also show that CMIP6 models not resolving currents through the English Channel cannot accurately simulate the effect of seasonal wind-stress changes on he NWES. Our results imply that using projections of annual mean RSLC may underestimate the projected changes in extreme coastal sea levels in spring and winter. Additionally, changes in the seasonal sea-level cycle may affect groundwater dynamics and the inundation characteristics of intertidal ecosystems.

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Coastal Sea Level Change from in the North Eastern Atlantic

10.5194/egusphere-egu2020-19345 ◽

2020 ◽

Author(s):

Luciana Fenoglio-Marc ◽

Bernd Uebbing ◽

Jürgen Kusche ◽

Salvatore Dinardo

Keyword(s):

Time Series ◽

Sea Level ◽

Sea Level Change ◽

Altimeter Data ◽

Level Change ◽

The North ◽

North Eastern ◽

Coastal Sea

A significant part of the World population lives in the coastal zone, which is affected by coastal sea level rise and extreme events. Our hypothesis is that the most accurate sea level height measurements are derived from the&#160;Synthetic Aperture Altimetry (SAR) mode. This study analyses the output of dedicated processing and assesses their impacts on the sea level change of the North-Eastern Atlantic.&#160;It will be shown that SAR altimetry reduces the minimum usable distance from five to three kilometres when the dedicated coastal retrackers SAMOSA+ and SAMOSA++ are applied to data processed in SAR mode. A similar performance is achieved with altimeter data processed in pseudo low resolution mode (PLRM) when the Spatio-Temporal Altimeter sub-waveform Retracker (STAR) is used. Instead the Adaptive Leading Edge Sub-waveform retracker (TALES) applied to PLRM is less performant.&#160;SAR processed altimetry can recover the sea level heights with 4 cm accuracy up to 3-4 km distance to coast. Thanks to the low noise of SAR mode data, the instantaneous SAR and in-situ data have the highest agreement, with the smallest standard deviation of differences and the highest correlation.&#160;A co-location of the altimeter data near the tide gauge is the best choice for merging in-situ and altimeter data. The r.m.s. (root mean squared) differences between altimetry and in-situ heights remain large in estuaries and in coastal zone with high tidal regimes, which are still challenging regions.&#160;The geophysical parameters derived from CryoSat-2 and Sentinel-3A measurements have similar accuracy, but the different repeat cycle of the two missions locally affects the constructed time-series.The impact of these new SAR observations in climate change studies is assessed by evaluating regional and local time series of sea level. At distances to coast smaller than 10 Kilometers the sea level change derived from SAR and LRM data is in good agreement. The long-term sea level variability derived from monthly time-series of LRM altimetry and of land motion-corrected tide gauges agrees within 1 mm/yr for half of in-situ German stations.&#160;The long-term sea level variability derived from SAR data show a similar behaviour with increasing length of the time series.&#160;

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Time-Series Prediction of Sea Level Change in the East Coast of Peninsular Malaysia from the Supervised Learning Approach

International Journal of Design & Nature and Ecodynamics ◽

10.18280/ijdne.150314 ◽

2020 ◽

Vol 15 (3) ◽

pp. 409-415

Author(s):

Vivien Lai ◽

Marlinda Malek ◽

Samsuri Abdullah ◽

Sarmad Latif ◽

Ali Ahmed

Keyword(s):

Time Series ◽

Supervised Learning ◽

Sea Level ◽

East Coast ◽

Time Series Prediction ◽

Sea Level Change ◽

Peninsular Malaysia ◽

Learning Approach ◽

Level Change

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Sea-Level Reconstructions and Archaeological Indicators: A Case Study from the Submerged Hellenistic Harbor at Akko, Israel

10.5194/egusphere-egu21-2376 ◽

2021 ◽

Author(s):

Alyssa Victoria Pietraszek ◽

Oded Katz ◽

Jacob Sharvit ◽

Beverly Goodman-Tchernov

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Sea Level Change ◽

Relative Sea Level ◽

Factors Affecting ◽

Sea Levels ◽

Level Change ◽

Structural Deterioration ◽

Short And Long Term

With the impending threat of continued sea-level rise and coastal inundation, it is important to understand the short- and long-term factors affecting sea-level in a particular region. Such a feat can be accomplished by turning to indicators of past sea-levels. This study aims to highlight the utility of archaeological indicators in sea-level reconstructions, using Akko on Israel&#8217;s northern Mediterranean micro-tidal coast as a case study. Here, installations belonging to the maritime metropolis&#8217; Hellenistic Period (3rd to 1st centuries BCE) harbor, which have well-constrained chronological and elevational limitations, were identified at depths averaging 1.1 to 1.2 meters below present sea-level (mbpsl). These features would have been located sub-aerially during the time of their construction and use, indicating a change in relative sea-level in the area since this time. Utilizing a multiple proxy approach incorporating marine sedimentological and geoarchaeological methodologies with previously recorded regional data, three possible explanations for this apparent sea-level change were assessed: structural deterioration, sea-level rise, and vertical tectonic movements. This study revealed that, although signs of structural deterioration are apparent in some parts of the quay, this particular harbor installation is well-established as in situ as it has a continuous upper surface and its southern edge is built directly on the underlying bedrock. Consequently, the harbor&#8217;s current submarine position can instead be attributed to sea-level change and/or vertical tectonic displacements. While this amount of sea-level rise (over 1 m) is in agreement with glacio-hydro-eustatic values suggested for other areas of the Mediterranean, it falls below those previously reported locally. In addition, most studies suggest that the tectonic movement along this stretch of coastline is negligible. These new data provide a reliable relative sea-level marker with very little error with regard to maximum sea-level, thereby renewing the overall consideration of the tectonic and sea-level processes that have been active along this stretch of coastline during the last 2,500 years.

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Global sea-level and ocean-mass budgets using advanced data products and uncertainty characterisation

10.5194/egusphere-egu21-10174 ◽

2021 ◽

Author(s):

Martin Horwath ◽

Anny Cazenave ◽

Keyword(s):

Time Series ◽

Sea Level ◽

Satellite Altimetry ◽

Sea Level Change ◽

Mass Change ◽

Level Change ◽

Ocean Mass ◽

Global Mean Sea Level ◽

Global Sea Level ◽

Global Mean

Studies of the global sea-level budget (SLB) and ocean-mass budget (OMB) are essential to assess the reliability of our knowledge of sea-level change and its contributors. The SLB is considered closed if the observed sea-level change agrees with the sum of independently assessed steric and mass contributions. The OMB is considered closed if the observed ocean-mass change is compatible with the sum of assessed mass contributions.&#160;Here we present results from the Sea-Level Budget Closure (SLBC_cci) project conducted in the framework of ESA&#8217;s Climate Change Initiative (CCI). We used data products from CCI projects as well as newly-developed products based on CCI products and on additional data sources. Our focus on products developed in the same framework allowed us to exercise a consistent uncertainty characterisation and its propagation to the budget closure analyses, where the SLB and the OMB are assessed simultaneously.&#160;We present time series of global mean sea-level changes from satellite altimetry; new time series of the global mean steric component generated from Argo drifter data with incorporation of sea surface temperature data; time series of ocean-mass change derived from GRACE satellite gravimetry; time series of global glacier mass change from a global glacier model; time series of mass changes of the Greenland Ice Sheet and the Antarctic Ice Sheet both from satellite radar altimetry and from GRACE; as well as time series of land water storage change from the WaterGAP global hydrological model. Our budget analyses address the periods 1993&#8211;2016 (covered by the satellite altimetry records) and 2003&#8211;2016 (covered by GRACE and the Argo drifter system). In terms of the mean rates of change (linear trends), the SLB is closed within uncertainties for both periods, and the OMB, assessable for 2003&#8211;2016 only, is also closed within uncertainties. Uncertainties (1-sigma) arising from the combined uncertainties of the elements of the different budgets considered are between 0.26 mm/yr and 0.40 mm/yr, that is, on the order of 10% of the magnitude of global mean sea-level rise, which is 3.05 &#177; 0.24 mm/yr and 3.65 &#177; 0.26 mm/yr for 1993-2016 and 2003-2016, respectively. We also assessed the budgets on a monthly time series basis. The statistics of monthly misclosure agrees with the combined uncertainties of the budget elements, which amount to typically 2-3 mm for the 2003&#8211;2016 period. We discuss possible origins of the residual misclosure.

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River-discharge effects on United States Atlantic and Gulf coast sea-level changes

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1805428115 ◽

2018 ◽

Vol 115 (30) ◽

pp. 7729-7734 ◽

Cited By ~ 29

Author(s):

Christopher G. Piecuch ◽

Klaus Bittermann ◽

Andrew C. Kemp ◽

Rui M. Ponte ◽

Christopher M. Little ◽

...

Keyword(s):

United States ◽

Sea Level ◽

River Discharge ◽

Sea Level Change ◽

The United States ◽

Ocean Dynamics ◽

Sea Level Changes ◽

Level Change ◽

Vertical Land Motion ◽

Coastal Sea

Identifying physical processes responsible for historical coastal sea-level changes is important for anticipating future impacts. Recent studies sought to understand the drivers of interannual to multidecadal sea-level changes on the United States Atlantic and Gulf coasts. Ocean dynamics, terrestrial water storage, vertical land motion, and melting of land ice were highlighted as important mechanisms of sea-level change along this densely populated coast on these time scales. While known to exert an important control on coastal ocean circulation, variable river discharge has been absent from recent discussions of drivers of sea-level change. We update calculations from the 1970s, comparing annual river-discharge and coastal sea-level data along the Gulf of Maine, Mid-Atlantic Bight, South Atlantic Bight, and Gulf of Mexico during 1910–2017. We show that river-discharge and sea-level changes are significantly correlated (p<0.01), such that sea level rises between 0.01 and 0.08 cm for a 1 km3 annual river-discharge increase, depending on region. We formulate a theory that describes the relation between river-discharge and halosteric sea-level changes (i.e., changes in sea level related to salinity) as a function of river discharge, Earth’s rotation, and density stratification. This theory correctly predicts the order of observed increment sea-level change per unit river-discharge anomaly, suggesting a causal relation. Our results have implications for remote sensing, climate modeling, interpreting Common Era proxy sea-level reconstructions, and projecting coastal flood risk.

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Closing the global and regional sea level budgets by combining multi-mission altimetry and GRACE(-FO) data

10.5194/egusphere-egu2020-3507 ◽

2020 ◽

Author(s):

Bernd Uebbing ◽

Christina Lück ◽

Roelof Rietbroek ◽

Kristin Vielberg ◽

Jürgen Kusche

Keyword(s):

Time Series ◽

Sea Level ◽

Sea Level Change ◽

Inversion Method ◽

Data Sets ◽

Sea Level Changes ◽

Steric Sea Level ◽

Level Change ◽

Spatial Coverage ◽

Regional Sea Level

Understanding present day sea level changes and their drivers requires the separation of the total sea level change into individual mass and steric related contributions. Total sea level rise has been observed continuously since 1993 providing a more than 25 year long time series of global and regional sea level variations. However, direct monitoring of ocean mass change has only been done since the start of the Gravity Recovery And Climate Experiment (GRACE) mission in 2002. It ended in 2017 and was succeeded by the follow-on mission (GRACE-FO) in 2018 leaving a gap of about 1 year. In the same time period of GRACE, since the early 2000s, a global array of freely drifting Argo floats samples temperature and salinity profiles of up to 2000m depth which can be converted to steric sea level change.By combining altimetry, GRACE(-FO) and Argo data sets it is possible to derive global and regional sea level budgets. The conventional approach is to analyze at least two of the data sets and derive the residual, or compare with the third one. A more recent approach is the global joint inversion method (Rietbroek et al., 2016) which fits forward-modeled spatial fingerprints to a combination of GRACE gravity data and Jason-1/-2 satellite altimetry data. This enables us, additionally, to separate altimetric sea level change into mass contributions from terrestrial hydrology, the melting of land glaciers and the ice-sheets in Greenland and Antarctica as well as contributions from steric sea level changes due to variations in ocean temperature and salinity. It also allows to include a data weighting scheme in the analysis.Here, we present global and regional sea level budget results from an updated inversion based on multi-mission altimetry (Jason-1/-2/-3, Envisat, Cryosat-2, Sentinel-3, &#8230;) providing better spatial coverage as well as new RL06 GRACE and GRACE-FO data which enables us to extend the time series of individual components of the sea level budget beyond the GRACE era from 2002-04 till 2019-06. The presented sea level budget is closed on global scale with a residual (unexplained) contribution of about 0.1 mm/yr, globally, originating in eddy-active regions. We provide consistent validation of our results against conventionally analyzed altimetry and GRACE data sets where we find agreement on global scales to be better than 0.1 mm/yr but a larger disagreement at regional scales as well as the implications of our results for deriving ocean heat content. We will also provide first results for filling the gap in the sea level budget estimates due to the gap between the GRACE and GRACE-FO missions by additionally incorporating time-variable gravity information from the Swarm mission as well as from Satellite Laser Ranging (SLR) to 5 satellites (Lageos-1/-2, Stella, Starlette, Ajisai).

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