scholarly journals Coastal sea level rise at Senetosa (Corsica) during the Jason altimetry missions

Ocean Science ◽  
2020 ◽  
Vol 16 (5) ◽  
pp. 1165-1182 ◽  
Author(s):  
Yvan Gouzenes ◽  
Fabien Léger ◽  
Anny Cazenave ◽  
Florence Birol ◽  
Pascal Bonnefond ◽  
...  
Keyword(s):  
High Resolution ◽  
Sea Level Rise ◽  
Sea Level ◽  
Leading Edge ◽  
Satellite System ◽  
Careful Examination ◽  
Coastal Zones ◽  
Coastal Sea ◽  
Potential Contributor ◽  
Global Navigation Satellite

Abstract. In the context of the ESA Climate Change Initiative project, we are engaged in a regional reprocessing of high-resolution (20 Hz) altimetry data of the classical missions in a number of the world's coastal zones. It is done using the ALES (Adaptive Leading Edge Subwaveform) retracker combined with the X-TRACK system dedicated to improve geophysical corrections at the coast. Using the Jason-1 and Jason-2 satellite data, high-resolution, along-track sea level time series have been generated, and coastal sea level trends have been computed over a 14-year time span (from July 2002 to June 2016). In this paper, we focus on a particular coastal site where the Jason track crosses land, Senetosa, located south of Corsica in the Mediterranean Sea, for two reasons: (1) the rate of sea level rise estimated in this project increases significantly in the last 4–5 km to the coast compared to what is observed further offshore, and (2) Senetosa is the calibration site for the TOPEX/Poseidon and Jason altimetry missions, which are equipped for that purpose with in situ instrumentation, in particular tide gauges and a Global Navigation Satellite System (GNSS) antenna. A careful examination of all the potential errors that could explain the increased rate of sea level rise close to the coast (e.g., spurious trends in the geophysical corrections, imperfect inter-mission bias estimate, decrease of valid data close to the coast and errors in waveform retracking) has been carried out, but none of these effects appear able to explain the trend increase. We further explored the possibility that it results from real physical processes. Change in wave conditions was investigated, but wave setup was excluded as a potential contributor because the magnitude was too low and too localized in the immediate vicinity of the shoreline. A preliminary model-based investigation about the contribution of coastal currents indicates that it could be a plausible explanation of the observed change in sea level trend close to the coast.

scholarly journals Coastal Sea Level rise at Senetosa (Corsica) during the Jason altimetry missions

2020 ◽  
Author(s):  
Yvan Gouzenes ◽  
Fabien Léger ◽  
Anny Cazenave ◽  
Florence Birol ◽  
Pascal Bonnefond ◽  
...  
Keyword(s):  
High Resolution ◽  
Sea Level Rise ◽  
Sea Level ◽  
Leading Edge ◽  
Careful Examination ◽  
Coastal Zones ◽  
Small Magnitude ◽  
Coastal Sea ◽  
Potential Contributor ◽  
Set Up

Abstract. In the context of the ESA Climate Change Initiative project, we are engaged in a regional reprocessing of high-resolution (20 Hz) altimetry data of the classical missions in a number of coastal zones worldwide. It is done using the ALES (Adaptive Leading Edge Subwaveform) retracker combined with the X-TRACK system dedicated to improve geophysical corrections at the coast. Using the Jason-1 & 2 satellite data, high-resolution, along-track sea level time series have been generated and coastal sea level trends have been computed over a 14-year time span (from July 2002 to June 2016). In this paper, we focus on a particular coastal site where a Jason track crosses land, Senetosa, located south of Corsica in the Mediterranean Sea, for two reasons: (1) the rate of sea level rise estimated in this project increases significantly in the last 4–5 km to the coast, compared to what is observed further offshore, and (2) Senetosa is the calibration site for the Topex/Poseidon and Jason altimetry missions, equipped for that purpose with in situ instrumentation, in particular tide gauges and GNSS antennas. A careful examination of all the potential errors that could explain the increased rate of sea level rise close to the coast (e.g., spurious trends in the geophysical corrections, imperfect intermission bias estimate, decrease of valid data close to the coast and errors in waveform retracking) has been carried out, but none of these effects appear able to explain the trend increase. We further explored the possibility it results from real physical processes. Change in wave conditions was investigated but wave set up was excluded as a potential contributor because of too small magnitude and too localized in the immediate vicinity of the shoreline. Preliminary model-based investigation about the contribution of coastal currents indicates that it could be a plausible explanation of the observed change in sea level trend close to the coast.

Performance Assessment of GNSS-R Polarimetric Observations for Sea Level Monitoring

2021 ◽  
Author(s):  
Mahmoud Rajabi ◽  
Mstafa Hoseini ◽  
Hossein Nahavandchi ◽  
Maximilian Semmling ◽  
Markus Ramatschi ◽  
...  
Keyword(s):  
Time Series ◽  
Circular Polarization ◽  
Sea Level ◽  
Tide Gauge ◽  
Satellite System ◽  
Sea Surface ◽  
Analysis Tool ◽  
Lower Accuracy ◽  
Coastal Sea ◽  
Global Navigation Satellite

<p>Determination and monitoring of the mean sea level especially in the coastal areas are essential, environmentally, and as a vertical datum. Ground-based Global Navigation Satellite System Reflectometry (GNSS-R) is an innovative way which is becoming a reliable alternative for coastal sea-level altimetry. Comparing to traditional tide gauges, GNSS-R can offer different parameters of sea surface, one of which is the sea level. The measurements derived from this technique can cover wider areas of the sea surface in contrast to point-wise observations of a tide gauge.  </p><p>We use long-term ground-based GNSS-R observations to estimate sea level. The dataset includes one-year data from January to December 2016. The data was collected by a coastal GNSS-R experiment at the Onsala space observatory in Sweden. The experiment utilizes three antennas with different polarization designs and orientations. The setup has one up-looking, and two sea-looking antennas at about 3 meters above the sea surface level. The up-looking antenna is Right-Handed Circular Polarization (RHCP). The sea-looking antennas with RHCP and Left-Handed Circular Polarization (LHCP) are used for capturing sea reflected Global Positioning System (GPS) signals. A dedicated reflectometry receiver (GORS type) provides In-phase and Quadrature (I/Q) correlation sums for each antenna based on the captured interferometric signal. The generated time series of I/Q samples from different satellites are analyzed using the Least Squares Harmonic Estimation (LSHE) method. This method is a multivariate analysis tool which can flexibly retrieve the frequencies of a time series regardless of possible gaps or unevenly spaced sampling. The interferometric frequency, which is related to the reflection geometry and sea level, is obtained by LSHE with a temporal resolution of 15 minutes. The sea level is calculated based on this frequency in six modes from the three antennas in GPS L1 and L2 signals.</p><p>Our investigation shows that the sea-looking antennas perform better compared to the up-looking antenna. The highest accuracy is achieved using the sea-looking LHCP antenna and GPS L1 signal. The annual Root Mean Square Error (RMSE) of 15-min GNSS-R water level time series compared to tide gauge observations is 3.7 (L1) and 5.2 (L2) cm for sea-looking LHCP, 5.8 (L1) and 9.1 (L2) cm for sea-looking RHCP, 6.2 (L1) and 8.5 (L2) cm for up-looking RHCP. It is worth noting that the GPS IIR block satellites show lower accuracy due to the lack of L2C code. Therefore, the L2 observations from this block are eliminated.</p>

scholarly journals Tracking of geodetic height of sea level in the west of Java Sea, Indonesia: A preliminary assessment

2019 ◽  
Vol 94 ◽  
pp. 01003 ◽  
Author(s):  
Poerbandono ◽  
Kosasih Prijatna ◽  
Irwan Gumilar
Keyword(s):  
Sea Level ◽  
Global Navigation Satellite System ◽  
Satellite System ◽  
Careful Examination ◽  
Navigation Satellite ◽  
The West ◽  
Geodetic Height ◽  
Java Sea ◽  
Global Navigation ◽  
Global Navigation Satellite

This paper assesses the agreement between observed heights of sea level from Global Navigation Satellite System (GNSS) and a global model of Mean Sea Surface (MSS). The assessment of the agreement is carried out according to the direct comparison between the height of MSS model and the geodetic height of actual sea level. Here, MSS is generated according to Gravity Recovery And Climate Experiment (GRACE) Gravity Model (GGM) and Mean Dynamic Ocean Topography (MDOT). The tracking of geodetic heights of actual sea level are done by Wide Area Differential (WA D) and Real Time Precise Point Positioning (RTPPP) Global Navigation Satellite System (GNSS) along an approximately 180 Nm SW-NE transect of away-return ship track in the west of the Java Sea, Indonesia. It is found that the overall agreement between geodetic height of sea level and MSS observed by WA DGNSS is 7.5 cm (away tracking), while those observed by RTPPP GNSS is 39.5 cm (away tracking) and 36.0 cm (return tracking). This work recommends selection of the best-fit tide model and careful examination on the dynamics of antenna offset due to vessel attitude.

scholarly journals Sea Level Rise Scenario for 2100 A.D. in the Heritage Site of Pyrgi (Santa Severa, Italy)

2019 ◽  
Author(s):  
Marco Anzidei ◽  
Fawzi Doumaz ◽  
Antonio Vecchio ◽  
Enrico Serpelloni ◽  
Luca Pizzimenti ◽  
...  
Keyword(s):  
High Resolution ◽  
Sea Level Rise ◽  
Sea Level ◽  
Storm Surges ◽  
Coastal Zones ◽  
Heritage Sites ◽  
Historical Structures ◽  
Vertical Land Motion ◽  
Climatic Scenarios ◽  
The Mediterranean

Sea level rise is one of the main factor of risk for the preservation of cultural heritage sites located along the coasts of the Mediterranean basin. Coastal retreat, erosion and storm surges are yet posing serious threats to archaeological and historical structures built along the coastal zones of this region. In order to assess the coastal changes by the end of 2100 under an expected sea level rise of about 1 m, a detailed determination of the current coastline position and the availability of high resolution DSM, is needed. This paper focuses on the use of very high-resolution UAV imagery for the generation of ultra-high resolution mapping of the coastal archaeological area of Pyrgi, near Rome (Italy). The processing of the UAV imagery resulted in the generation of a DSM and an orthophoto, with an accuracy of 1.94 cm/pixel. The integration of topographic data with two sea level rise projections in the IPCC AR5 2.6 and 8.5 climatic scenarios for this area of the Mediterranean, were used to map sea level rise scenarios for 2050 and 2100. The effects of the Vertical Land Motion (VLM) as estimated from two nearby continuous GPS stations located as much as close to the coastline, were included in the analysis. Relative sea level rise projections provide values at 0.30±0.15 cm by 2050 and 0.56±0.22 by 2100, for the IPCC AR5 8.5 scenarios and at 0.13±0.05 cm by 2050 and 0.17±0.22 by 2100, for the IPCC AR5 2.6 scenario. These values of rise will correspond to a potential beach loss between 12.6% and 23.5% in 2100 for RCP 2.6 and 8.5 scenarios, respectively, while during the highest tides the beach will be reduced up to 46.4%. With these sea level rise scenarios, Pyrgi with its nearby Etruscan temples and the medieval castle of Santa Severa will be soon exposed to high risk of marine flooding, especially during storm surges, thus requiring suitable adaptation strategies.

scholarly journals Sea Level Rise Scenario for 2100 A.D. in the Heritage Site of Pyrgi (Santa Severa, Italy)

2020 ◽  
Vol 8 (2) ◽  
pp. 64 ◽  
Author(s):  
Marco Anzidei ◽  
Fawzi Doumaz ◽  
Antonio Vecchio ◽  
Enrico Serpelloni ◽  
Luca Pizzimenti ◽  
...  
Keyword(s):  
High Resolution ◽  
Sea Level Rise ◽  
Sea Level ◽  
Storm Surges ◽  
Coastal Zones ◽  
Dune System ◽  
Intergovernmental Panel ◽  
Historical Structures ◽  
Vertical Land Motion ◽  
The Mediterranean

Sea level rise is one of the main risk factors for the preservation of cultural heritage sites located along the coasts of the Mediterranean basin. Coastal retreat, erosion, and storm surges are posing serious threats to archaeological and historical structures built along the coastal zones of this region. In order to assess the coastal changes by the end of 2100 under the expected sea level rise of about 1 m, we need a detailed determination of the current coastline position based on high resolution Digital Surface Models (DSM). This paper focuses on the use of very high-resolution Unmanned Aerial Vehicles (UAV) imagery for the generation of ultra-high-resolution mapping of the coastal archaeological area of Pyrgi, Italy, which is located near Rome. The processing of the UAV imagery resulted in the generation of a DSM and an orthophoto with an accuracy of 1.94 cm/pixel. The integration of topographic data with two sea level rise projections in the Intergovernmental Panel on Climate Change (IPCC) AR5 2.6 and 8.5 climatic scenarios for this area of the Mediterranean are used to map sea level rise scenarios for 2050 and 2100. The effects of the Vertical Land Motion (VLM) as estimated from two nearby continuous Global Navigation Satellite System (GNSS) stations located as close as possible to the coastline are included in the analysis. Relative sea level rise projections provide values at 0.30 ± 0.15 cm by 2050 and 0.56 ± 0.22 cm by 2100 for the IPCC AR5 8.5 scenarios and at 0.13 ± 0.05 cm by 2050 and 0.17 ± 0.22 cm by 2100, for the IPCC Fifth Assessment Report (AR5) 2.6 scenario. These values of rise correspond to a potential beach loss between 12.6% and 23.5% in 2100 for Representative Concentration Pathway (RCP) 2.6 and 8.5 scenarios, respectively, while, during the highest tides, the beach will be provisionally reduced by up to 46.4%. In higher sea level positions and storm surge conditions, the expected maximum wave run up for return time of 1 and 100 years is at 3.37 m and 5.76 m, respectively, which is capable to exceed the local dune system. With these sea level rise scenarios, Pyrgi with its nearby Etruscan temples and the medieval castle of Santa Severa will be exposed to high risk of marine flooding, especially during storm surges. Our scenarios show that suitable adaptation and protection strategies are required.

Land subsidence and sea-level rise for six coastal zones of the Mediterranean region: implications for flooding scenarios for 2100 from the SAVEMEDCOASTS-2 project

2021 ◽  
Author(s):  
Michele Crosetto ◽  
Marco Anzidei ◽  
Giovanna Forlenza ◽  
José Navarro ◽  
Petros Patias ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Land Subsidence ◽  
Mediterranean Region ◽  
Tide Gauge ◽  
Storm Surges ◽  
Satellite System ◽  
Coastal Zones ◽  
Intergovernmental Panel ◽  
The Mediterranean

<p>Here we show and discuss the first results arising from the SAVEMEDCOASTS-2 Project (Sea Level Rise Scenarios along the Mediterranean Coasts - 2, funded by the European Commission ECHO), which aims to respond to the need for people and assets prevention from natural disasters in the Mediterranean coastal zones placed at less than 1 m above sea level, which are vulnerable to the combined effect of sea-level rise and land subsidence.</p><p>We use geodetic data from global navigation satellite system (GNSS), synthetic aperture radar interferometric measurements (InSAR), Lidar and tide gauge data, and the latest IPCC - SROCC projections of sea-level rise released by the Intergovernmental Panel on Climate Change, to estimate the Relative Sea Level Rise to realize marine flooding scenarios expected for 2100 AD in six targeted areas of the Mediterranean region.</p><p>We focus on the Ebro (Spain), Rhone (France), and Nile (Egypt) river deltas; the reclamation area of Basento (Italy), the coastal plain of Thessaloniki (Greece), and the Venice lagoon (Italy). Results, from Copernicus Sentinel-1A (S1A) and Sentinel-1B (S1B) sensors, highlighted the variable spatial rates of land subsidence up to some cm/yr in most of the investigated areas representing a relevant driver of local SLR. All the investigated zones show valuable coastal infrastructures and natural reserves where SLR and land subsidence are exacerbating coastal retreat, land flooding, and storm surges.</p><p>The hazard implications for the population living along the shore should push land planners and decision-makers to take into account scenarios similar to that reported in this study for cognizant coastal management.</p>

Observed coastal sea level changes in Southeast Asia from retracked altimetry over 2002-present

2020 ◽  
Author(s):  
Yvan Gouzènes ◽  
Fabien Léger ◽  
Anny Cazenave ◽  
Florence Birol ◽  
Marcello Passaro ◽  
...  
Keyword(s):  
Time Series ◽  
Southeast Asia ◽  
Sea Level ◽  
Processing System ◽  
Leading Edge ◽  
Open Ocean ◽  
Small Scale ◽  
Coastal Zones ◽  
Sea Level Changes ◽  
Coastal Sea

<p>We present results of contemporary coastal sea level changes along the coasts of different<br>regions of Southeast Asia derived from a dedicated reprocessing of satellite altimetry data.<br>This work is performed in the context of the ESA ‘Climate Change Initiative’ sea level project<br>dedicated to provide altimetry-based sea level time series in the world coastal zones. Here is<br>focus on Southeast Asian Seas. High-frequency (20 Hz) sea level data from the Jason-1,<br>Jason-2 and Jason-3 missions are considered. The data are first retracked using the ALES<br>adaptive leading edge subwaveform retracker and further combined with the X-TRACK<br>processing system developed to optimize the accuracy of the sea level time series in coastal<br>oceans. Rates of sea level change are estimated over the period 2002-present along the Jasontracks,<br>from the open ocean to the coast. Different coastal sea level trend behaviors are<br>observed over the study period: constant trends from open ocean to the coast, sometimes<br>decreasing trends, or increasing trends within the last few km to the coast. We compare the<br>computed coastal trends in Southeast Asia with results we previously obtained in other<br>regions (Mediterranean Sea, Western Africa, Northeastern Europe). We further discuss the<br>various small-scale processes able to explain departure of the coastal sea level rate from the<br>offshore (open ocean) rate.</p>

Coastal sea level changes in Africa from retracked Jason altimetry over 2002-2020

2021 ◽  
Author(s):  
Yvan Gouzenes ◽  
Anny Cazenave ◽  
Fabien Léger ◽  
Florence Birol ◽  
Marcello Passaro ◽  
...  
Keyword(s):  
Sea Level ◽  
Leading Edge ◽  
Small Scale ◽  
Coastal Zones ◽  
Sea Level Changes ◽  
Ice Melt ◽  
The World ◽  
Coastal Sea ◽  
Fresh Water Input ◽  
Global Mean

<p>Climate-related sea level changes in the world coastal zones result from the superposition of the global mean rise due to ocean warming and land ice melt, regional changes mostly caused by non-uniform ocean thermal expansion and salinity changes, and small-scale coastal processes (e.g., shelf currents, wind & waves changes, fresh water input from rivers, etc.). So far, satellite altimetry has provided global gridded sea level time series up to 10-15 km to the coast only, preventing estimation of sea level changes very close to the coast. In the context of the ESA Climate Change Initiative coastal sea level project, we have developed a complete reprocessing of high-resolution (20 Hz) Jason-1, 2 and 3 altimetry data along the world coastal zones using the ALES (Adaptative Leading Edge Subwaveform) retracker combined with the XTRACK system dedicated to improve geophysical corrections at the coast. Here we present coastal sea level trends over the period 2002-2020 along the whole African continent. Different coastal sea level trend behaviors are observed over the study period. We compare the computed coastal trends in Africa with results we previously obtained in other regions (Mediterranean Sea, Northeastern Europe, north Indian Sea, southeast Asia and Australia).</p>

scholarly journals An open-source low-cost sensor for SNR-based GNSS reflectometry: design and long-term validation towards sea-level altimetry

GPS Solutions ◽  
2021 ◽  
Vol 25 (2) ◽  
Author(s):  
M. A. R. Fagundes ◽  
I. Mendonça-Tinti ◽  
A. L. Iescheck ◽  
D. M. Akos ◽  
F. Geremia-Nievinski
Keyword(s):  
Open Source ◽  
Sea Level ◽  
Tide Gauge ◽  
Signal To Noise Ratio ◽  
Low Cost ◽  
Satellite System ◽  
Open Science ◽  
Coastal Sea ◽  
Commercial Off The Shelf ◽  
Global Navigation Satellite

AbstractMonitoring sea level is critical due to climate change observed over the years. Global Navigation Satellite System Reflectometry (GNSS-R) has been widely demonstrated for coastal sea-level monitoring. The use of signal-to-noise ratio (SNR) observations from ground-based stations has been especially productive for altimetry applications. SNR records an interference pattern whose oscillation frequency allows retrieving the unknown reflector height. Here we report the development and validation of a complete hardware and software system for SNR-based GNSS-R. We make it available as open source based on the Arduino platform. It costs about US$200 (including solar power supply) and requires minimal assembly of commercial off-the-shelf components. As an initial validation towards applications in coastal regions, we have evaluated the system over approximately 1 year by the Guaíba Lake in Brazil. We have compared water-level altimetry retrievals with independent measurements from a co-located radar tide gauge (within 10 m). The GNSS-R device ran practically uninterruptedly, while the reference radar gauge suffered two malfunctioning periods, resulting in gaps lasting for 44 and 38 days. The stability of GNSS-R altimetry results enabled the detection of miscalibration steps (10 cm and 15 cm) inadvertently introduced in the radar gauge after it underwent maintenance. Excluding the radar gaps and its malfunctioning periods (reducing the time series duration from 317 to 147 days), we have found a correlation of 0.989 and RMSE of 2.9 cm in daily means. To foster open science and lower the barriers for entry in SNR-based GNSS-R research and applications, we make a complete bill of materials and build tutorials freely available on the Internet so that interested researchers can  replicate the system.

scholarly journals High-rate altimetry in SNR-based GNSS-R: Proof-of-concept of a synthetic vertical array

2021 ◽  
Author(s):  
Mauricio Kenji Yamawaki ◽  
Felipe Geremia-Nievinski ◽  
João Francisco Monico
Keyword(s):  
Sea Level ◽  
Signal To Noise Ratio ◽  
Satellite System ◽  
High Rate ◽  
Proof Of Concept ◽  
Radio Waves ◽  
Vertical Array ◽  
Remote Sensing Technique ◽  
Single Antenna ◽  
Global Navigation Satellite

Global Navigation Satellite System Reflectometry (GNSS-R) has emerged as a promising remote sensing technique for coastal sea level monitoring. The GNSS-R based on signal-to-noise ratio (SNR) observations employs a single antenna and a conventional receiver. It performs best for low elevation satellites, where direct and reflected radio waves are very similar in polarization and direction of arrival. One of the disadvantages of SNR-based GNSS-R for sea level altimetry is its low temporal resolution, which is of the order of one hour for each independent satellite pass. Here we present a proof-of-concept based on a synthetic vertical array. It exploits the mechanical movement of a single antenna at high rate (about 1 Hz). SNR observations can then be fit to a known modulation, of the order of the antenna sweeping rate. We demonstrate that centimetric altimetry precision can be achieved in a 5-minute session. [©2021 IEEE]

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