Overlapping sea level time series measured using different technologies: an example from the REDMAR Spanish network

Abstract. This paper addresses the problems of overlapping sea level time series measured using different technologies and sometimes from different locations inside a harbour. The renovation of the Spanish REDMAR (RED de MAReógrafos) sea level network is taken here as an example of the difficulties encountered: up to seventeen old tide gauge stations have been replaced by radar tide gauges all around the Spanish coast, in order to fulfil the new international requirements on tsunami detection. Overlapping periods between old and new stations have allowed the comparison of records in different frequency ranges and the determination of the impact of this change of instrumentation on the long-term sea level products such as tides, surges and mean sea levels. The differences encountered are generally within the values expected, taking into account the characteristics of the different sensors, the different sampling strategies and sometimes the different locations inside the harbours. However, our analysis has also revealed in some cases the presence of significant scale errors that, overlapping with datum differences and uncertainties, as well as with hardware problems in many new radar gauges, may hinder the generation of coherent and continuous sea level time series. Comparisons with nearby stations have been combined with comparisons with altimetry time series close to each station in order to better determine the sources of error and to guarantee the precise relationships between the sea level time series from the old and the new tide gauges.

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Nonlinear absolute sea-level patterns in the long-term-trend tide gauges of the East Coast of North America

Nonlinear Engineering ◽

10.1515/nleng-2021-0001 ◽

2021 ◽

Vol 10 (1) ◽

pp. 1-15

Author(s):

Alberto Boretti

Keyword(s):

North America ◽

Sea Level ◽

East Coast ◽

Tide Gauge ◽

Tide Gauges ◽

Sea Levels ◽

Term Trend ◽

The Absolute ◽

Long Term Trend

Abstract The paper provides an estimate of the latest relative and absolute rates of rise and accelerations of the sea levels for the East Coast of North America. The computation is based on the long-term trend (LTT) tide gauge records of the relative sea levels and the Global Navigation Satellite System (GNSS) time series of the absolute position of fixed dome nearby the tide gauges. The GNSS result is used to infer the subsidence or uplift of the tide gauge instrument. The data of 33 LTT tide stations with more than 80 years of data are shown. The average relative sea-level rise is +2.22 mm/yr. subjected to a small, positive average acceleration of +0.0027 mm/yr2. The average absolute velocity of the tide gauge instruments is −0.52 mm/yr. translating in an average absolute sea-level rise of +1.70 mm/yr. This is the first paper publishing a comprehensive survey of the absolute sea-level rates of rise along the East Coast of North America using the reliable information of relative sea-level rates of rise from LTT tide gauges, plus the absolute subsidence rates from GNSS antennas that are close to the tide gauges installations.

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Effects of the basin dynamics on sea level rise in the Black Sea

10.5194/os-2016-69 ◽

2016 ◽

Author(s):

A. A. Kubryakov ◽

S. V. Stanichny ◽

D. L. Volkov

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Black Sea ◽

Tide Gauge ◽

The Black Sea ◽

Tide Gauges ◽

Tide Gauge Records ◽

Sea Levels ◽

The Difference

Abstract. Satellite altimetry measurements show that magnitude of the Black Sea level trends is spatially uneven. While the basin-averaged sea level was increasing at a rate of 3.15 mm/year from 1993 to 2014, the sea level rise varied from 0.15–2.5 mm/year in the central part to 3.5–3.8 mm/year in coastal areas and 5 mm/year in the southwestern part of the sea. These differences are caused by changes in the large- and mesoscale circulation of the Black Sea. A long-term increase of the cyclonic wind curl over the basin from 1979 to 2014 strengthened divergence in the center of the Black Sea that led to an increase of sea level near the coast and a decrease in the center of the basin. Changes in the distribution and intensity of mesoscale eddies caused the formation of the local extremes of sea level trend. The variability of the dynamic sea level (DSL) – the difference between the local and the basin-averaged sea levels – contributes significantly (up to ~ 50 % of the total variance) to the seasonal and interannual variability of sea level in the basin. The DSL variability in the Black Sea depends strongly on the basin-averaged wind curl and is well reconstructed using the ERA-Interim winds from 1979 to present, including the time when altimetry data was unavailable. The reconstruction can be used to correct historical tide gauges data for dynamic effects, which are usually neglected in the analysis of the Black Sea tide gauge records.

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Estimating contribution of high-frequency sea-level oscillations to the extreme sea levels in the Adriatic Sea

10.5194/egusphere-egu21-4602 ◽

2021 ◽

Author(s):

Krešimir Ruić ◽

Jadranka Šepić ◽

Maja Karlović ◽

Iva Međugorac

Keyword(s):

Time Series ◽

Sea Level ◽

High Frequency ◽

Adriatic Sea ◽

Tide Gauge ◽

Data Series ◽

Sea Levels ◽

Short Period ◽

Extreme Sea Levels ◽

Sea Level Oscillations

Extreme sea levels are known to hit the Adriatic Sea and to occasionally cause floods that produce severe material damage. Whereas the contribution of longer-period (T > 2 h) sea-level oscillations to the phenomena has been well researched, the contribution of the shorter period (T <&#160;2 h) oscillations is yet to be determined. With this aim, data of 1-min sampling resolution were collected for 20 tide gauges, 10 located at the Italian (north and west) and 10 at the Croatian (east) Adriatic coast. Analyses were done on time series of 3 to 15 years length, with the latest data coming from 2020, and with longer data series available for the Croatian coast. Sea level data were thoroughly checked, and spurious data were removed.&#160;For each station, extreme sea levels were defined as events during which sea level surpasses its 99.9 percentile value. The contribution of short-period oscillations to extremes was then estimated from corresponding high-frequency (T < 2 h) series. Additionally, for four Croatian tide gauge stations (Rovinj, Bakar, Split, and Dubrovnik), for period of 1956-2004, extreme sea levels were also determined from the hourly sea level time series, with the contribution of short-period oscillations visually estimated from the original tide gauge charts.&#160;&#160;Spatial and temporal distribution of contribution of short-period sea-level oscillations to the extreme sea level in the Adriatic were estimated. It was shown that short-period sea-level oscillation can significantly contribute to the overall extremes and should be considered when estimating flooding levels.&#160;

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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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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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Pacific Sea Levels Rising Very Slowly and Not Accelerating

Quaestiones Geographicae ◽

10.2478/quageo-2019-0007 ◽

2019 ◽

Vol 38 (1) ◽

pp. 179-184 ◽

Cited By ~ 1

Author(s):

Albert Parker ◽

Clifford Ollier

Keyword(s):

Pacific Ocean ◽

Sea Level ◽

Relative Rate ◽

Tide Gauges ◽

Sea Levels ◽

The Past ◽

The Pacific ◽

The Pacific Ocean ◽

Long Term Trend

AbstractOver the past decades, detailed surveys of the Pacific Ocean atoll islands show no sign of drowning because of accelerated sea-level rise. Data reveal that no atoll lost land area, 88.6% of islands were either stable or increased in area, and only 11.4% of islands contracted. The Pacific Atolls are not being inundated because the sea level is rising much less than was thought. The average relative rate of rise and acceleration of the 29 long-term-trend (LTT) tide gauges of Japan, Oceania and West Coast of North America, are both negative, −0.02139 mm yr−1and −0.00007 mm yr−2respectively. Since the start of the 1900s, the sea levels of the Pacific Ocean have been remarkably stable.

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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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Assessment of Tide Gauge Biases and Precision by the Combination of Multiple Collocated Time Series

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-18-0235.1 ◽

2019 ◽

Vol 36 (10) ◽

pp. 1983-1996 ◽

Cited By ~ 2

Author(s):

Kevin Gobron ◽

Olivier de Viron ◽

Guy Wöppelmann ◽

Étienne Poirier ◽

Valérie Ballu ◽

...

Keyword(s):

Time Series ◽

Sea Level ◽

Variance Component ◽

Tide Gauge ◽

Electrical Contact ◽

Combination Method ◽

Tide Gauges ◽

Contact Probe ◽

Component Estimation ◽

Cross Calibration

AbstractThis study proposes a method for the cross calibration of tide gauges. Based on the combination of at least three collocated sea level time series, it takes advantage of the least squares variance component estimation (LS-VCE) method to assess both sea level biases and uncertainties in real conditions. The method was applied to a multi-instrument experiment carried out on Aix Island, France, in 2016. Six tide gauges were deployed to carry out simultaneous sea level recordings for 11 h. The best results were obtained with an electrical contact probe, which reaches a 3-mm uncertainty. The method allows us to assess both the biases and the precision—that is, the full accuracy—for each instrument. The results obtained with the proposed combination method have been compared to that of a buddy-checking method. It showed that the combination of all the time series also provides more precise bias estimates.

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LEVEL VARIABILITY OF THE SEA OF OKHOTSK COASTAL AREAS AT THE BEGINING OF THE 21ST CENTURY AND ITS REPRESENTATIONIN THE GLOBAL REANALYSIS DATABASES

THE LIFE OF THE EARTH ◽

10.29003/m1770.0514-7468.2020_42_4/411-424 ◽

2020 ◽

Vol 42 (4) ◽

pp. 411-424

Author(s):

Aleksandr KHOLOPTSEV ◽

Sergey PODPORIN

Keyword(s):

Sea Level ◽

Sea Of Okhotsk ◽

Tide Gauge ◽

Coastal Areas ◽

Global Ocean ◽

Satellite Monitoring ◽

Climate Data ◽

Sea Levels ◽

The Sea Of Okhotsk

The paper aims to investigate basic features of modern long-term variations of the Okhotsk Sea level in its coastal areas and establish feasibility of certain retrospective analysis databases usage for determination of mean rates of the above processes. The reanalysis databases considered include Global Ocean Physics Reanalysis GLORYS12v.1 by the Copernicus Marine Environment Monitoring Service and ICDC-reanalysis supported by the Integrated Climate Data Center, which provide coverage of the sea in question. The raised problem is of significant interest for physiographers, oceanographers and involved in coastal shipping and marine safety in the Sea of Okhotsk. Long-term sea level variations are most accurately monitored by tide gauge stations, which, however, are scarce along the coast of the sea in question. Less accurate and not uniformly available through easier to use and collect data is the satellite monitoring by radar altimeters. Global retrospective analyses based on mathematical modelling are considered to be an effective instrument to assess sea levels at any given time at any point.

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Historical tide-gauge sea-level observations in Alicante and Santander (Spain) since the 19th century

10.5194/egusphere-egu2020-7596 ◽

2020 ◽

Author(s):

Marta Marcos ◽

Bernat Puyol ◽

Angel Amores ◽

Begoña Pérez Gómez ◽

M. Ángeles Fraile ◽

...

Keyword(s):

Time Series ◽

Sea Level ◽

New Records ◽

Tide Gauge ◽

Mediterranean Coast ◽

Northern Spain ◽

National Archives ◽

The 19Th Century ◽

Daily Time

A set of historical tide-gauge sea-level records from two locations in Santander (Northern Spain) and Alicante (Spanish Mediterranean coast) have been recovered from logbooks stored in national archives. Sea-level measurements have been digitised, quality-controlled and merged into three consistent sea-level time series (two in Alicante and one in Santander) using high precision levelling information. The historical sea-level record in Santander consists of a daily time series spanning the period 1876-1924 and it is further connected to the modern tide-gauge station nearby, ensuring datum continuity up to the present. The sea-level record in Alicante starts in 1870 with daily averaged values until the 1920s and hourly afterwards, and is still in operation, thus representing the longest tide-gauge sea-level time series in the Mediterranean Sea. The long-term consistency and reliability of the new records is discussed based on the comparison with nearby tide gauge time series.

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