Monitoring of Vertical Land Motion at Tide Gauges Using Time-Series Sequential SBAS Technique

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.&#160;Keywords: Vertical land motion, Sea Level Changes, Tide gauge, Satellite altimetry, GPS, CGPS

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Vertical land motion in the Iberian Atlantic coast and its implications for sea level change evaluation

Journal of Applied Geodesy ◽

10.1515/jag-2020-0012 ◽

2020 ◽

Vol 14 (3) ◽

pp. 361-378

Author(s):

V. B. Mendes ◽

S. M. Barbosa ◽

D. Carinhas

Keyword(s):

Time Series ◽

Sea Level ◽

Satellite Altimetry ◽

Tide Gauge ◽

Atlantic Coast ◽

Sea Level Change ◽

Tide Gauges ◽

Tide Gauge Records ◽

Level Change ◽

Vertical Land Motion

AbstractIn this study, we estimate vertical land motion for 35 stations primarily located along the coastline of Portugal and Spain, using GPS time series with at least eight years of observations. Based on this set of GPS stations, our results show that vertical land motion along the Iberian coastline is characterized, in general, by a low to moderate subsidence, ranging from −2.2 mm yr−1 to 0.4 mm yr−1, partially explained by the glacial isostatic adjustment geophysical signal. The estimates of vertical land motion are subsequently applied in the analysis of tide gauge records and compared with geocentric estimates of sea level change. Geocentric sea level for the Iberian Atlantic coast determined from satellite altimetry for the last three decades has a mean of 2.5 ± 0.6 mm yr−1, with a significant range, as seen for a subset of grid points located in the vicinity of tide gauge stations, which present trends varying from 1.5 mm yr−1 to 3.2 mm yr−1. Relative sea level determined from tide gauges for this region shows a high degree of spatial variability, that can be partially explained not only by the difference in length and quality of the time series, but also for possible undocumented datum shifts, turning some trends unreliable. In general, tide gauges corrected for vertical land motion produce smaller trends than satellite altimetry. Tide gauge trends for the last three decades not corrected for vertical land motion range from 0.3 mm yr−1 to 5.0 mm yr−1 with a mean of 2.6 ± 1.4 mm yr−1, similar to that obtained from satellite altimetry. When corrected for vertical land motion, we observe a reduction of the mean to ∼1.9 ± 1.4 mm yr−1. Actions to improve our knowledge of vertical land motion using space geodesy, such as establishing stations in co-location with tide gauges, will contribute to better evaluate sea level change and its impacts on coastal regions.

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Monitoring the Vertical Land Motion of Tide Gauges and Its Impact on Relative Sea Level Changes in Korean Peninsula Using Sequential SBAS-InSAR Time-Series Analysis

Remote Sensing ◽

10.3390/rs13010018 ◽

2020 ◽

Vol 13 (1) ◽

pp. 18

Author(s):

Suresh Krishnan Palanisamy Vadivel ◽

Duk-jin Kim ◽

Jungkyo Jung ◽

Yang-Ki Cho ◽

Ki-Jong Han

Keyword(s):

Time Series ◽

Synthetic Aperture Radar ◽

Sea Level ◽

Korean Peninsula ◽

Tide Gauge ◽

Synthetic Aperture ◽

Tide Gauges ◽

Sea Level Changes ◽

Vertical Land Motion

The relative sea-level changes from tide gauges in the Korean peninsula provide essential information to understand the regional and global mean sea-level changes. Several corrections to raw tide gauge records are required to account for coastal vertical land motion (VLM), regional and local coastal variability. However, due to the lack of in-situ measurements such as leveling data and the Global Navigation Satellite System (GNSS), making precise assessments of VLM at the tide gauges is still challenging. This study aims to address the above limitation to assess the VLM in the Korean tide gauges using the time-series Interferometric Synthetic Aperture Radar (InSAR) technique. For 10 tide gauges selected in the Korean peninsula, we applied the Stanford Method for Persistent Scatterers (StaMPS)—Small Baseline Subset (SBAS) method to C-band Sentinel-1 A/B Synthetic Aperture Radar (SAR) data acquired during 2014/10–2020/05, with the novel sequential interferograms pair selection approach to increase the slowly decorrelating filtered phase (SDFP) pixels density near the tide gauges. Our findings show that overall the tide gauges in the Korean peninsula are stable, besides the largest VLM observed at Pohang tide gauge station (East Sea) of about −26.02 mm/year; also, higher rates of uplift (>1 mm/year) were observed along the coast of Yellow Sea (Incheon TG and Boryeong TG) and higher rates of subsidence (<−2 mm/year) were observed at Jeju TG and Seogwipo TG. Our approach estimates the rate of VLM at selected tide gauges with an unprecedented spatial and temporal resolution and is applicable when the in-situ and GNSS observations are not available.

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Reprocessed height time series for GPS stations

Solid Earth ◽

10.5194/se-4-23-2013 ◽

2013 ◽

Vol 4 (1) ◽

pp. 23-41 ◽

Cited By ~ 8

Author(s):

S. Rudenko ◽

N. Schön ◽

M. Uhlemann ◽

G. Gendt

Keyword(s):

Time Series ◽

Tide Gauge ◽

Tide Gauges ◽

Sea Level Changes ◽

Tide Gauge Records ◽

Vertical Land Motion ◽

Global Positioning ◽

Typical Behaviour ◽

The Common ◽

Continuous Gps

Abstract. Precise weekly positions of 403 Global Positioning System (GPS) stations located worldwide are obtained by reprocessing GPS data of these stations for the time span from 4 January 1998 until 29 December 2007. The processing algorithms and models used as well as the solution and results obtained are presented. Vertical velocities of 266 GPS stations having a tracking history longer than 2.5 yr are computed; 107 of them are GPS stations located at tide gauges (TIGA observing stations). The vertical velocities calculated in this study are compared with the estimates from the co-located tide gauges and other GPS solutions. The formal errors of the estimated vertical velocities are 0.01–0.80 mm yr−1. The vertical velocities of our solution agree within 1 mm yr−1 with those of the recent solutions (ULR5 and ULR3) of the Université de La Rochelle for about 67–75 per cent of the common stations. Examples of typical behaviour of station height changes are given and interpreted. The derived height time series and vertical motions of continuous GPS at tide gauges stations can be used for correcting the vertical land motion in tide gauge records of sea level changes.

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Validation of sea surface heights from satellite altimetry along the Indian coast

10.5194/egusphere-egu21-4862 ◽

2021 ◽

Author(s):

Milaa Murshan ◽

Balaji Devaraju ◽

Nagarajan Balasubramanian ◽

Onkar Dikshit

Keyword(s):

Time Series ◽

Sea Level ◽

Satellite Altimetry ◽

Tide Gauge ◽

Atmospheric Correction ◽

North Indian Ocean ◽

Sea Surface ◽

Indian Coast ◽

Vertical Land Motion ◽

And Performance

Satellite altimetry provides measurements of sea surface height of centimeter-level accuracy over open oceans. However, its accuracy reduces when approaching the coastal areas and over land regions. Despite this downside, altimetric measurements are still applied successfully in these areas through altimeter retracking processes. This study aims to calibrate and validate retracted sea level data of Envisat, ERS-2, Topex/Poseidon, Jason-1, 2, SARAL/AltiKa, Cryosat-2 altimetric missions near the Indian coastline. We assessed the reliability, quality, and performance of these missions by comparing eight tide gauge (TG) stations along the Indian coast. These are Okha, Mumbai, Karwar, and Cochin stations in the Arabian Sea, and Nagapattinam, Chennai, Visakhapatnam, and Paradip in the Bay of Bengal. To compare the satellite altimetry and TG sea level time series, both datasets are transformed to the same reference datum. Before the calculation of the bias between the altimetry and TG sea level time series, TG data are corrected for Inverted Barometer (IB) and Dynamic Atmospheric Correction (DAC). Since there are no prior VLM measurements in our study area, VLM is calculated from TG records using the same procedure as in the Technical Report NOS organization CO-OPS 065.&#160;Keywords&#8212; Tide gauge, Sea level, North Indian ocean, satellite altimetry, Vertical land motion

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Recent sea level rise on Ireland's east coast based on multiple tide gauge analysis

10.5194/os-2020-81 ◽

2020 ◽

Author(s):

Amin Shoari Nejad ◽

Andrew C. Parnell ◽

Alice Greene ◽

Brian P. Kelleher ◽

Gerard McCarthy

Keyword(s):

Time Series ◽

Sea Level Rise ◽

Sea Level ◽

Continuous Time ◽

East Coast ◽

Tide Gauge ◽

Tide Gauges ◽

Missing Value ◽

Global Average ◽

Good Agreement

Abstract. We analysed multiple tide gauges from the east coast of Ireland over the period 1938–2018. We validated the different time series against each other and performed a missing value imputation exercise, which enabled us to produce a homogenised record. The recordings of all tide gauges were found to be in good agreement between 2003–2015, though this was markedly less so from 2016 to the present. We estimate the sea level rise in Dublin port for this period at 10 mm yr−1. The rate over the longer period of 1938–2015 was 1.67 mm yr−1 which is in good agreement with the global average. We found that the rate of sea level rise in the longer term record is cyclic with some extreme upward and downward trends. However, starting around 1980, Dublin has seen significantly higher rates that have been always positive since 1996, and this is mirrored in the surrounding gauges. Furthermore, our analysis indicates an increase in sea level variability since 1980. Both decadal rates and continuous time rates are calculated and provided with uncertainties in this paper.

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Sinking Tide Gauge Revealed by Space-borne InSAR: Implications for Sea Level Acceleration at Pohang, South Korea

Remote Sensing ◽

10.3390/rs11030277 ◽

2019 ◽

Vol 11 (3) ◽

pp. 277 ◽

Cited By ~ 5

Author(s):

Suresh Palanisamy Vadivel ◽

Duk-jin Kim ◽

Jungkyo Jung ◽

Yang-Ki Cho ◽

Ki-Jong Han ◽

...

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Tide Gauge ◽

Tide Gauges ◽

Tide Gauge Records ◽

Relative Sea Level ◽

Tide Gauge Station ◽

Sea Level Acceleration ◽

Vertical Land Motion ◽

Gauge Station

Vertical land motion at tide gauges influences sea level rise acceleration; this must be addressed for interpreting reliable sea level projections. In recent years, tide gauge records for the Eastern coast of Korea have revealed rapid increases in sea level rise compared with the global mean. Pohang Tide Gauge Station has shown a +3.1 cm/year sea level rise since 2013. This study aims to estimate the vertical land motion that influences relative sea level rise observations at Pohang by applying a multi-track Persistent Scatter Interferometric Synthetic Aperture Radar (PS-InSAR) time-series analysis to Sentinel-1 SAR data acquired during 2015–2017. The results, which were obtained at a high spatial resolution (10 m), indicate vertical ground motion of −2.55 cm/year at the Pohang Tide Gauge Station; this was validated by data from a collocated global positioning system (GPS) station. The subtraction of InSAR-derived subsidence rates from sea level rise at the Pohang Tide Gauge Station is 6 mm/year; thus, vertical land motion significantly dominates the sea level acceleration. Natural hazards related to the sea level rise are primarily assessed by relative sea level changes obtained from tide gauges; therefore, tide gauge records should be reviewed for rapid vertical land motion along the vulnerable coastal areas.

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Using continuous GPS and absolute gravity to separate vertical land movements and changes in sea-level at tide-gauges in the UK

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2006.1746 ◽

2006 ◽

Vol 364 (1841) ◽

pp. 917-930 ◽

Cited By ~ 45

Author(s):

F.N Teferle ◽

R.M Bingley ◽

S.D.P Williams ◽

T.F Baker ◽

A.H Dodson

Keyword(s):

Time Series ◽

Sea Level ◽

Tide Gauge ◽

Absolute Gravity ◽

Tide Gauges ◽

Tide Gauge Record ◽

Vertical Movements ◽

Movement Component ◽

The Uk ◽

Continuous Gps

Researchers investigating climate change have used historical tide-gauge measurements from all over the world to investigate the changes in sea-level that have occurred over the last century or so. However, such estimates are a combination of any true sea-level variations and any vertical movements of the land at the specific tide-gauge. For a tide- gauge record to be used to determine the climate related component of changes in sea-level, it is therefore necessary to correct for the vertical land movement component of the observed change in sea-level. In 1990, the Institute of Engineering Surveying and Space Geodesy and Proudman Oceanographic Laboratory started developing techniques based on the Global Positioning System (GPS) for measuring vertical land movements (VLM) at tide-gauges in the UK. This paper provides brief details of these early developments and shows how they led to the establishment of continuous GPS (CGPS) stations at a number of tide-gauges. The paper then goes on to discuss the use of absolute gravity (AG), as an independent technique for measuring VLM at tide-gauges. The most recent results, from CGPS time-series dating back to 1997 and AG time-series dating back to 1995/1996, are then used to demonstrate the complementarity of these two techniques and their potential for providing site-specific estimates of VLM at tide-gauges in the UK.

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The zone of influence: matching sea level variability from coastal altimetry and tide gauges for vertical land motion estimation

Ocean Science ◽

10.5194/os-17-35-2021 ◽

2021 ◽

Vol 17 (1) ◽

pp. 35-57

Author(s):

Julius Oelsmann ◽

Marcello Passaro ◽

Denise Dettmering ◽

Christian Schwatke ◽

Laura Sánchez ◽

...

Keyword(s):

Sea Level ◽

Spatial Scales ◽

Tide Gauges ◽

Sea Level Changes ◽

Relative Sea Level ◽

Sea Level Variability ◽

Vertical Land Motion ◽

Spatial Coverage ◽

Coupling Procedure ◽

Zone Of Influence

Abstract. Vertical land motion (VLM) at the coast is a substantial contributor to relative sea level change. In this work, we present a refined method for its determination, which is based on the combination of absolute satellite altimetry (SAT) sea level measurements and relative sea level changes recorded by tide gauges (TGs). These measurements complement VLM estimates from the GNSS (Global Navigation Satellite System) by increasing their spatial coverage. Trend estimates from the SAT and TG combination are particularly sensitive to the quality and resolution of applied altimetry data as well as to the coupling procedure of altimetry and TGs. Hence, a multi-mission, dedicated coastal along-track altimetry dataset is coupled with high-frequency TG measurements at 58 stations. To improve the coupling procedure, a so-called “zone of influence” (ZOI) is defined, which confines coherent zones of sea level variability on the basis of relative levels of comparability between TG and altimetry observations. Selecting 20 % of the most representative absolute sea level observations in a 300 km radius around the TGs results in the best VLM estimates in terms of accuracy and uncertainty. At this threshold, VLMSAT-TG estimates have median formal uncertainties of 0.58 mm yr−1. Validation against GNSS VLM estimates yields a root mean square (rmsΔVLM) of VLMSAT-TG and VLMGNSS differences of 1.28 mm yr−1, demonstrating the level of accuracy of our approach. Compared to a reference 250 km radius selection, the 300 km zone of influence improves trend accuracies by 15 % and uncertainties by 35 %. With increasing record lengths, the spatial scales of the coherency in coastal sea level trends increase. Therefore, the relevance of the ZOI for improving VLMSAT-TG accuracy decreases. Further individual zone of influence adaptations offer the prospect of bringing the accuracy of the estimates below 1 mm yr−1.

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Two-dimensional reconstruction of past sea level (1950–2003) from tide gauge data and an Ocean General Circulation Model

Climate of the Past ◽

10.5194/cp-5-217-2009 ◽

2009 ◽

Vol 5 (2) ◽

pp. 217-227 ◽

Cited By ~ 37

Author(s):

W. Llovel ◽

A. Cazenave ◽

P. Rogel ◽

A. Lombard ◽

M. B. Nguyen

Keyword(s):

Time Series ◽

Sea Level ◽

General Circulation ◽

Tide Gauge ◽

Circulation Model ◽

Ocean General Circulation Model ◽

Two Dimensional ◽

Tide Gauges ◽

Dimensional Reconstruction ◽

Ocean General Circulation

Abstract. A two-dimensional reconstruction of past sea level is proposed at yearly interval over the period 1950–2003 using tide gauge records from 99 selected sites and 44-year long (1960–2003) 2°×2° sea level grids from the OPA/NEMO ocean general circulation model with data assimilation. We focus on the regional variability and do not attempt to compute the global mean trend. An Empirical Orthogonal Function decomposition of the reconstructed sea level grids over 1950–2003 displays leading modes that reflect two main components: (1) a long-term (multi-decadal), regionally variable signal and (2) an interannual, regionally variable signal dominated by the signature of El Nino-Southern Oscillation. Tests show that spatial trend patterns of the 54-year long reconstructed sea level significantly depend on the temporal length of the two-dimensional sea level signal used for the reconstruction (i.e., the length of the gridded OPA/NEMO sea level time series). On the other hand, interannual variability is well reconstructed, even when only ~10-years of model grids are used. The robustness of the results is assessed, leaving out successively each of the 99 tide gauges used for the reconstruction and comparing observed and reconstructed time series at the non considered tide gauge site. The reconstruction performs well at most tide gauges, especially at interannual frequency.

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