scholarly journals Sea Level Changes Along Global Coasts from Satellite Altimetry, GPS and Tide Gauge

10.5772/58972 ◽  
2015 ◽  
Author(s):  
Guiping Feng ◽  
Shuanggen Jin
Keyword(s):  
Sea Level ◽  
Satellite Altimetry ◽  
Tide Gauge ◽  
Sea Level Changes

scholarly journals Recent Sea Level Change in the Black Sea from Satellite Altimetry and Tide Gauge Observations

2020 ◽  
Vol 9 (3) ◽  
pp. 185 ◽  
Author(s):  
Nevin Avşar ◽  
Şenol Kutoğlu
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Black Sea ◽  
Satellite Altimetry ◽  
Tide Gauge ◽  
The Black Sea ◽  
Sea Level Changes ◽  
Early 19Th Century ◽  
Mean Sea Level ◽  
The Mean

Global mean sea level has been rising at an increasing rate, especially since the early 19th century in response to ocean thermal expansion and ice sheet melting. The possible consequences of sea level rise pose a significant threat to coastal cities, inhabitants, infrastructure, wetlands, ecosystems, and beaches. Sea level changes are not geographically uniform. This study focuses on present-day sea level changes in the Black Sea using satellite altimetry and tide gauge data. The multi-mission gridded satellite altimetry data from January 1993 to May 2017 indicated a mean rate of sea level rise of 2.5 ± 0.5 mm/year over the entire Black Sea. However, when considering the dominant cycles of the Black Sea level time series, an apparent (significant) variation was seen until 2014, and the rise in the mean sea level has been estimated at about 3.2 ± 0.6 mm/year. Coastal sea level, which was assessed using the available data from 12 tide gauge stations, has generally risen (except for the Bourgas Station). For instance, from the western coast to the southern coast of the Black Sea, in Constantza, Sevastopol, Tuapse, Batumi, Trabzon, Amasra, Sile, and Igneada, the relative rise was 3.02, 1.56, 2.92, 3.52, 2.33, 3.43, 5.03, and 6.94 mm/year, respectively, for varying periods over 1922–2014. The highest and lowest rises in the mean level of the Black Sea were in Poti (7.01 mm/year) and in Varna (1.53 mm/year), respectively. Measurements from six Global Navigation Satellite System (GNSS) stations, which are very close to the tide gauges, also suggest that there were significant vertical land movements at some tide gauge locations. This study confirmed that according to the obtained average annual phase value of sea level observations, seasonal sea level variations in the Black Sea reach their maximum annual amplitude in May–June.

Sea level in Thule measured with tide gauge, GNSS-IR and Satellite Altimetry

2020 ◽  
Author(s):  
Trine S. Dahl-Jensen ◽  
Shfaqat Abbas Khan ◽  
Simon D.P. Williams ◽  
Ole B. Andersen ◽  
Carsten A. Ludwigsen
Keyword(s):  
Sea Level ◽  
Satellite Altimetry ◽  
Tide Gauge ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Sea Level Changes ◽  
Level Measurement ◽  
Time Period ◽  
The Right ◽  
Gps Station

<p>Recent studies show that under the right conditions relative sea level can be measured using GNSS interferometric reflectometry (GNSS-IR). We test the possibility of using an existing GNET GPS station in Thule, Greenland, to measure inter annual changes in sea level by comparing sea level measurements from GNSS-IR with tide gauge observations and satellite altimetry data. GNET is a network of 56 permanent GPS stations positioned on the bedrock around the edge fo the Greenland ice sheet with the main purpose of monitoring ice mass changes. Currently, Thule is the only location in Greenland where we have both a tide gauge and a GPS station that is suitable for sea level measurement covering the same time period for more than a couple of years. If successful a number of other GPS stations are also expected to be suitable for GNSS-IR measurements of sea level. However, they lack the tide gauge station for testing.<br>We compare the measured sea level with uplift measured using the GPS and modeled from height changes of the Greenland ice sheet as well as sea surface temperatures and modeled sea level changes from gravimetry, in order to investigate the origin of sea level changes in the region.  <br> </p>

Estimation of Vertical Land Motion at the Tide Gauges in Turkey

2020 ◽  
Author(s):  
Muharrem Hilmi Erkoç ◽  
Uğur Doğan ◽  
Seda Özarpacı ◽  
Hasan Yildiz ◽  
Erdinç Sezen
Keyword(s):  
Time Series ◽  
Sea Level ◽  
Satellite Altimetry ◽  
Tide Gauge ◽  
Marmara Sea ◽  
Tide Gauges ◽  
Sea Level Changes ◽  
Coordinate Time ◽  
Coordinate Time Series ◽  
Vertical Land Motion

<p>This study aims to estimate vertical land motion (VLM) at tide gauges (TG), located in the Mediterranean, Aegean and the Marmara Sea coasts of Turkey, from differences of multimission satellite altimetry and TG sea level time series. Initially, relative sea level trends are estimated at 7 tide gauges stations operated by the Turkish General Directorate of Mapping over the period 2001-2019. Subsequently, absolute sea level trends independent from VLM are computed from multimission satellite altimetry data over the same period. We have computed estimates of linear trends of difference time series between altimetry and tide gauge sea level after removing seasonal signals by harmonic analysis from each time series to estimate the vertical land motion (VLM) at tide gauges. Traditional way of VLM determination at tide gauges is to use GPS@TG or preferably CGPS@TG data. We therefore, processed these GPS data, collected over the years by several TG-GPS campaigns and by continuous GPS stations close to the TG processed by GAMIT/GLOBK software. Subsequently, the GPS and CGPS vertical coordinate time series are used to estimate VLM. These two different VLM estimates, one from GPS and CGPS coordinate time series and other from altimetry-TG sea level time series differences are compared.</p><p> </p><p><strong>Keywords: Vertical land motion, Sea Level Changes, Tide gauge, Satellite altimetry, GPS, CGPS </strong></p>

scholarly journals Optimal mathematical and statistical models to estimate vertical crustal movements using satellite altimetry and tide gauge data

2019 ◽  
Vol 9 (1) ◽  
pp. 144-153
Author(s):  
H. Bâki Iz ◽  
T. Y. Yang ◽  
C. K. Shum ◽  
C. Y. Kuo
Keyword(s):  
Sea Level ◽  
Statistical Models ◽  
Satellite Altimetry ◽  
Tide Gauge ◽  
Crustal Movement ◽  
Sea Level Changes ◽  
Unknown Parameters ◽  
Vertical Crustal Movement ◽  
Proposed Model ◽  
Systematic Effects

Abstract Knowledge of vertical crustal movement is fundamental to quantify absolute sea level changes at tide gauge locations as well as for satellite altimetry calibration validations. While GPS measurements at collocated tide gauge stations fulfill this need, currently only few hundred tide gauge stations are equipped with GPS, and their measurements do not span a long period of time. In the past, several studies addressed this problem by calculating relative and geocentric trends from the tide gauge and satellite altimetry measurements respectively, and then difference the two trends to calculate the rate of changes at the tide gauge stations. However, this approach is suboptimal. This study offers an optimal statistical protocol based on the method of condition equations with unknown parameters. An example solution demonstrates the proposed mathematical and statistical models’ optimality in estimating vertical crustal movement and its standard error by comparing them with the results of current methods. The proposed model accounts for the effect of autocorrelations in observed tide gauge and satellite altimetry sea level time series, adjusts observed corrections such as inverted barometer effects, and constraints tide gauge and satellite altimeter measurement to close. The new model can accommodate estimating other systematic effects such as pole tides that are not eliminated by differencing.

scholarly journals Measuring Coastal Absolute Sea-Level Changes Using GNSS Interferometric Reflectometry

2021 ◽  
Vol 13 (21) ◽  
pp. 4319
Author(s):  
Dongju Peng ◽  
Lujia Feng ◽  
Kristine M. Larson ◽  
Emma M. Hill
Keyword(s):  
Sea Level ◽  
Satellite Altimetry ◽  
Tide Gauge ◽  
Global Navigation Satellite Systems ◽  
Coastal Zones ◽  
Sea Level Changes ◽  
Tide Gauge Records ◽  
Sea Levels ◽  
Satellite Systems ◽  
Linear Trends

Rising sea levels pose one of the greatest threats to coastal zones. However, sea-level changes near the coast, particularly absolute sea-level changes, have been less well monitored than those in the open ocean. In this study, we aim to investigate the potential of Global Navigation Satellite Systems Interferometric Reflectometry (GNSS-IR) to measure coastal absolute sea-level changes and tie on-land (coastal GNSS) and offshore (satellite altimetry) observations into the same framework. We choose three coastal GNSS stations, one each in regions of subsidence, uplift and stable vertical land motions, to derive both relative sea levels and sea surface heights (SSH) above the satellite altimetry reference ellipsoid from 2008 to 2020. Our results show that the accuracy of daily mean sea levels from GNSS-IR is <1.5 cm compared with co-located tide-gauge records, and amplitudes of annual cycle and linear trends estimated from GNSS-IR measurements and tide-gauge data agree within uncertainty. We also find that the de-seasoned and de-trended SSH time series from GNSS-IR and collocated satellite altimetry are highly correlated and the estimated annual amplitudes and linear trends statistically agree well, indicating that GNSS-IR has the potential to monitor coastal absolute sea-level changes and provide valuable information for coastal sea-level and climate studies.

The sources of sea-level rise in the Mediterranean Sea since 1960

2021 ◽  
Author(s):  
Francisco Mir Calafat ◽  
Thomas Frederikse ◽  
Kevin Horsburgh ◽  
Nadim Dayoub
Keyword(s):  
Sea Level Rise ◽  
Mediterranean Sea ◽  
Sea Level ◽  
Satellite Altimetry ◽  
Tide Gauge ◽  
Sea Level Changes ◽  
Tide Gauge Records ◽  
Land Mass ◽  
The Mediterranean ◽  
Dynamic Sea Level

&lt;p&gt;Sea-level change is geographically non-uniform, with regional departures that can reach several times the global average. Characterizing this spatial variability and understanding its causes is crucial to the design of adaptation strategies for sea-level rise. This, as it turns out, is no easy feat, primarily due to the sparseness of the observational sea-level record in time and space. Long tide gauge records are restricted to a few locations along the coast. Satellite altimetry offers a better spatial coverage but only since 1992. In the Mediterranean Sea, the tide gauge network is heavily biased towards the European shorelines, with only one record with at least 35 years of data on the African coasts. Past studies have attempted to address the difficulties related to this data sparseness in the Mediterranean Sea by combining the available tide gauge records with satellite altimetry observations. The vast majority of such studies represent sea level through a combination of altimetry-derived empirical orthogonal functions whose temporal amplitudes are then inferred from the tide gauge data. Such methods, however, have tremendous difficulty in separating trends and variability, make no distinction between relative and geocentric sea level, and tell us nothing about the causes of sea level changes. Here, we combine observational data from tide gauges and altimetry with sea-level fingerprints of land-mass changes through a Bayesian hierarchical model to quanify the sources of sea-level rise since 1960 at any arbitrary location in the Mediterranean Sea. We find that Mediterranean sea level rose at a relatively low rate from 1960 to 1990, primarily due to dynamic sea-level changes in the nearby Atlantic, at which point it started rising significantly faster with comparable contributions from dynamic sea level and land-mass changes.&lt;/p&gt;

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