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

<p><span>A</span>ccurate knowledge of sea level change, especially close to the coast, is of major importance in order to analyze <span>and</span> understand drivers of local sea level change and to plan coastal protection measures. <span>S</span>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’s groundtrack.</p><p>The <span>altimeter emits</span> a radar pulse from the satellite to the Earth’s surface and measure the power reflected over time from the radar footprint forming a so called “waveform”. 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 <span>increasingly</span> uncertain or even fail when the satellite groundtrack <span>approaches the coastline</span>. In order to still derive meaningful geophysical parameters it is necessary to reprocess or “retrack” those waveforms with specialized algorithms resulting in improved estimates.</p><p>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 <span>Brown model used in CA-STAR</span> is replaced by the Signal model Involving Numerical Convolution for SAR (SINCS) model, already implemented in the Technical University Darmstadt – University Bonn SAR-Reduced SAR (TUDaBo SAR-RDSAR) processing scheme.</p><p><span>T</span>he combination of the updated STARv2.5 processing scheme with the SINCS <span>model</span> (STARS) allows to <span>retrieve</span> high quality sea level estimates for contemporary DDA altimeter missions. We will <span>provide</span> validation results for Cryosat-2 and Sentinel-3 data in the North Sea region <span>for the </span><span>time</span><span> period</span> 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 <span>for </span>DDA. While originally developed for coastal regions, the STAR processing scheme also leads to improved open ocean results.</p>

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.

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 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

scholarly journals Salt-marsh reconstructions of relative sea-level change in the North Atlantic during the last 2000 years

2014 ◽  
Vol 99 ◽  
pp. 1-16 ◽  
Author(s):  
Natasha L.M. Barlow ◽  
Antony J. Long ◽  
Margot H. Saher ◽  
W. Roland Gehrels ◽  
Mark H. Garnett ◽  
...  
Keyword(s):  
Salt Marsh ◽  
Sea Level ◽  
North Atlantic ◽  
Sea Level Change ◽  
Relative Sea Level ◽  
Level Change ◽  
The North ◽  
The North Atlantic

Coastal Sea Level Change from in the North Eastern Atlantic

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

&lt;p&gt;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&amp;#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.&amp;#160;&lt;/p&gt;&lt;p&gt;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.&amp;#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.&amp;#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.&amp;#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.&lt;/p&gt;&lt;p&gt;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.&amp;#160;The long-term sea level variability derived from SAR data show a similar behaviour with increasing length of the time series.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

scholarly journals The Flux-Anomaly-Forced Model Intercomparison Project (FAFMIP) contribution to CMIP6: investigation of sea-level and ocean climate change in response to CO<sub>2</sub> forcing

2016 ◽  
Vol 9 (11) ◽  
pp. 3993-4017 ◽  
Author(s):  
Jonathan M. Gregory ◽  
Nathaelle Bouttes ◽  
Stephen M. Griffies ◽  
Helmuth Haak ◽  
William J. Hurlin ◽  
...  
Keyword(s):  
Sea Level ◽  
North Atlantic ◽  
Water Flux ◽  
Sea Level Change ◽  
Model Intercomparison ◽  
Ocean Climate ◽  
Level Change ◽  
The North ◽  
Intercomparison Project ◽  
Flux Perturbation

Abstract. The Flux-Anomaly-Forced Model Intercomparison Project (FAFMIP) aims to investigate the spread in simulations of sea-level and ocean climate change in response to CO2 forcing by atmosphere–ocean general circulation models (AOGCMs). It is particularly motivated by the uncertainties in projections of ocean heat uptake, global-mean sea-level rise due to thermal expansion and the geographical patterns of sea-level change due to ocean density and circulation change. FAFMIP has three tier-1 experiments, in which prescribed surface flux perturbations of momentum, heat and freshwater respectively are applied to the ocean in separate AOGCM simulations. All other conditions are as in the pre-industrial control. The prescribed fields are typical of pattern and magnitude of changes in these fluxes projected by AOGCMs for doubled CO2 concentration. Five groups have tested the experimental design with existing AOGCMs. Their results show diversity in the pattern and magnitude of changes, with some common qualitative features. Heat and water flux perturbation cause the dipole in sea-level change in the North Atlantic, while momentum and heat flux perturbation cause the gradient across the Antarctic Circumpolar Current. The Atlantic meridional overturning circulation (AMOC) declines in response to the heat flux perturbation, and there is a strong positive feedback on this effect due to the consequent cooling of sea-surface temperature in the North Atlantic, which enhances the local heat input to the ocean. The momentum and water flux perturbations do not substantially affect the AMOC. Heat is taken up largely as a passive tracer in the Southern Ocean, which is the region of greatest heat input, while the weakening of the AMOC causes redistribution of heat towards lower latitudes. Future analysis of these and other phenomena with the wider range of CMIP6 FAFMIP AOGCMs will benefit from new diagnostics of temperature and salinity tendencies, which will enable investigation of the model spread in behaviour in terms of physical processes as formulated in the models.

scholarly journals Organic stratigraphy and its applications with examples from the North American Western Interior and Antarctica

1992 ◽  
Vol 6 ◽  
pp. 147-147
Author(s):  
Stephen R. Jacobson ◽  
Rosemary A. Askin
Keyword(s):  
Organic Matter ◽  
Sea Level ◽  
Organic Geochemistry ◽  
Sea Level Change ◽  
Molecular Data ◽  
Hydrocarbon Exploration ◽  
Level Change ◽  
The North ◽  
Global Sea Level ◽  
Age Relations

Both insoluble (particulate) and soluble (molecular) sedimentary organic matter carry signatures of physical, chemical, and biological processes. These signatures may reflect (a) primary age-diagnostic, organism-specific, and environmentally-sensitive processes; (b) secondary factors related to mode of transportation, deposition, and preservation; and (c) tertiary agents that indicate post-burial alteration of the organic matter. Application of any or all organic matter data recorded in rocks can be used to solve geologic problems.Organic stratigraphy may be applied to hydrocarbon exploration. Our example uses both particulate and molecular data to reconstruct the age relations of Cretaceous-Lower Tertiary sediments in Wyoming, to determine the age of thrust fault motion, and to demonstrate constraints on the timing of upward petroleum migration to available trapped reservoirs.Another perspective helps establish chronostratigraphic frameworks for correlations of global sea-level change. Our example from Antarctic sediments that span the Cretaceous-Tertiary boundary reflects perturbations in relative sea-level and the consequential changes in the distribution of organic particulates from marine and terrestrial regimes. These data can be compared to age-equivalent data from other parts of the world, and test global sea-level change.Both of these applications demonstrate the versatility of organic matter in solving geologic problems. Data from contemporaneous land plants, freshwater and marine organic-walled micro-organisms provide clues on their lifestyle and subsequent afterlife alteration. Organic stratigraphy represents a long anticipated integration of several paleontological disciplines. It combines aspects of palynology, organic geochemistry, paleobotany, and coal petrography into a coherent science, with an enhanced capability to provide significant applications in the future.

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