Reconstruction and Projection of Sea Level Around the Korean Peninsula Using Cyclostationary Empirical Orthogonal Functions

Abstract. Since the advent of the modern satellite altimeter era, the understanding of the sea level has increased dramatically. The satellite altimeter record, however, dates back only to the 1990s. The tide gauge record, on the other hand, extends through the 20th century, but with poor spatial coverage when compared to the satellites. Many studies have been conducted to extend the spatial resolution of the satellite data into the past by finding novel ways to combine the satellite data and tide gauge data in what are known as sea level reconstructions. However, most of the reconstructions of sea level were conducted on a global scale, leading to reduced accuracy on regional levels, particularly where there are relatively few tide gauges. The sea around the Korean Peninsula is one such area with few tide gauges prior to 1960. In this study, new methods are proposed to reconstruct the past sea level and project the future sea level around the Korean Peninsula. Using spatial patterns obtained from a cyclo-stationary empirical orthogonal function decomposition of satellite data, we reconstruct sea level over the time period from 1900 to 2014. Sea surface temperature data and altimeter data are used simultaneously in the reconstruction process, leading to an elimination of reliance on tide gauge data. Although the tide gauge data was not used in the reconstruction process, the reconstructed results showed better agreement with the tide gauge observations in the region than previous studies that incorporated the TG data. This study demonstrates a reconstruction technique that can be used on regional levels, with particular emphasis on areas with poor tide gauge coverage.

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Reconstruction of sea level around the Korean Peninsula using cyclostationary empirical orthogonal functions

Ocean Science ◽

10.5194/os-14-959-2018 ◽

2018 ◽

Vol 14 (5) ◽

pp. 959-970 ◽

Cited By ~ 1

Author(s):

Se-Hyeon Cheon ◽

Benjamin D. Hamlington ◽

Kyung-Duck Suh

Keyword(s):

Sea Level ◽

Satellite Data ◽

Korean Peninsula ◽

Tide Gauge ◽

Tide Gauges ◽

Tide Gauge Data ◽

Satellite Altimeter ◽

Reconstruction Process ◽

Spatial Coverage ◽

Gauge Data

Abstract. Since the advent of the modern satellite altimeter era, the understanding of the sea level has increased dramatically. The satellite altimeter record, however, dates back only to the 1990s. The tide gauge record, on the other hand, extends through the 20th century but with poor spatial coverage when compared to the satellites. Many studies have been conducted to create a dataset with the spatial coverage of the satellite datasets and the temporal length of the tide gauge records by finding novel ways to combine the satellite data and tide gauge data in what is known as sea level reconstruction. However, most of the reconstructions of sea level were conducted on a global scale, leading to reduced accuracy on regional levels, especially when there are relatively few tide gauges. The seas around the Korean Peninsula are one such area with few tide gauges before 1960. In this study, new methods are proposed to reconstruct past sea level around the Korean Peninsula. Using spatial patterns obtained from a cyclostationary empirical orthogonal function decomposition of satellite data, we reconstruct sea level over the period from 1900 to 2014. Sea surface temperature data and altimeter data are used simultaneously in the reconstruction process, leading to an elimination of reliance on tide gauge data. Although we did not use the tide gauge data in the reconstruction process, the reconstructed sea level has a better agreement with the tide gauge observations in the region than previous studies that incorporated the tide gauge data. This study demonstrates a reconstruction technique that can potentially be used at regional levels, with particular emphasis on areas with poor tide gauge coverage.

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Review and Assessment of gap-filling methods from tide-gauges: Maxima missing at the Esbjerg, Denmark station, before 1910.

10.5194/egusphere-egu2020-4487 ◽

2020 ◽

Author(s):

Peter Thejll

Keyword(s):

Sea Level ◽

Tide Gauge ◽

Model Fit ◽

Tide Gauges ◽

Harmonic Model ◽

Gap Filling ◽

Tide Gauge Data ◽

Tide Gauge Record ◽

Long Baseline ◽

Gauge Data

Information on extremes of the sea-level is obtained from tide-gauge records. &#160;Such records may have gaps.Estimates of potential changes in the size and/or frequency of sea-level extremes are hampered by long gaps, or when just the high extremes are missing due, e.g. to equipment failure.Methods used for filling such gaps can be based on having multiple records from gauges near each other; but what to do if there is only one record? This problem can typically occur when old tide-gauge records are used -- the use of multiple recorders at the same place is more wide-spread today. However, especially older and therefore longer records hold the key to obtaining long-baseline insights into the temporal evolution of extreme tides and thus impacts of e.g. climate change.In this work, we review and assess methods for gap filling. We asses using the 'known truth' method, i.e. by applying realistic gaps to complete gauge records and reconstructing and then comparing errors calculated as the diffrence between modelled and actual values. &#160;We compare a simple harmonic model fit method to various spline methods as well as Neural network and deep learning approches. &#160;We also test a hybrid method which uses not just tide-gauge data but also air pressure readings from a meteorological station near the tide-gauge.We then attempt to fill in the missing maxima of the Esbjerg, Denmark hourly tide-gauge record since 1889. Particularly, before 1910 the maxima above 300 cm are missing (Bijl, et al., 1999), and we try to fill these in.

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Aegean Sea-Level Variability in the Past Half-Century Based on Tide Gauge Data

International Journal of Environment and Geoinformatics ◽

10.30897/ijegeo.1014344 ◽

2022 ◽

Vol 9 (1) ◽

pp. 162-169

Author(s):

Cem ŞENDURAN ◽

Sedat KABDAŞLI

Keyword(s):

Sea Level ◽

Tide Gauge ◽

Aegean Sea ◽

Tide Gauge Data ◽

Sea Level Variability ◽

Half Century ◽

The Past ◽

Past Half Century ◽

Gauge Data ◽

Past Half

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Measuring rates of present-day relative sea-level rise in low-elevation coastal zones: A critical evaluation

10.5194/os-2018-75 ◽

2018 ◽

Cited By ~ 1

Author(s):

Molly E. Keogh ◽

Torbjörn E. Törnqvist

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Land Surface ◽

Tide Gauge ◽

Tide Gauges ◽

Coastal Zones ◽

Tide Gauge Data ◽

Relative Sea Level ◽

Gauge Data ◽

Coastal Louisiana

Abstract. Although tide gauges are the primary source of data used to calculate multi-decadal to century-scale rates of relative sea-level change, we question the reliability of tide-gauge data in rapidly subsiding low-elevation coastal zones (LECZs). Tide gauges measure relative sea-level rise (RSLR) with respect to the base of associated benchmarks. Focusing on coastal Louisiana, the largest LECZ in the United States, we find that these benchmarks (n = 35) are anchored an average of 21.5 m below the land surface. Because at least 60 % of subsidence occurs in the top 5–10 m of the sediment column in this area, tide gauges in coastal Louisiana do not capture the primary contributor to RSLR. Similarly, GPS stations (n = 10) are anchored an average of > 14.3 m below the land surface and therefore also do not capture shallow subsidence. As a result, tide gauges and GPS stations in coastal Louisiana, and likely in LECZs worldwide, systematically underestimate rates of RSLR as experienced at the land surface. We present an alternative approach that explicitly measures RSLR in LECZs with respect to the land surface and eliminates the need for tide-gauge data. Shallow subsidence is measured by rod surface-elevation table‒marker horizons (RSET-MHs) and added to measurements of deep subsidence from GPS data, plus sea-level rise from satellite altimetry. We show that for a LECZ the size of coastal Louisiana (25,000–30,000 km2), about 40 RSET-MH instruments suffice to collect useful data. Rates of RSLR obtained from this approach are substantially higher than rates as inferred from tide-gauge data. We therefore conclude that LECZs may be at higher risk of flooding, and within a shorter time horizon, than previously assumed.

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Tide gauge data archaeology provides natural subsidence rates along the coasts of the Po Plain and of the Veneto-Friuli Plain, Italy

Geophysical Journal International ◽

10.1093/gji/ggaa602 ◽

2020 ◽

Author(s):

S Zerbini ◽

S Bruni ◽

F Raicich

Keyword(s):

Time Series ◽

Sea Level ◽

Tide Gauge ◽

Anthropogenic Activities ◽

Reliable Estimate ◽

Tide Gauges ◽

Tide Gauge Data ◽

Northern Adriatic ◽

Po Plain ◽

Gauge Data

Summary In Northern Italy, natural subsidence affects the Po and Veneto-Friuli Plains. Anthropogenic activities which started during the 1930s enhanced the natural rates considerably. Information on land lowering can be obtained not only by geodetic or geological data, but also analyzing and comparing sea-level time series of neighboring tide gauges. In the Northern Adriatic, several tide gauge stations were operational before the onset of the anthropogenic activities. We analyzed data spanning the period 1873–1922 from Marina di Ravenna, Venice and Trieste, in Italy. The 1897–1922 data of Pula, Croatia, were also considered for the analysis, but this time series was finally discarded because too short. Trieste, located in a relatively stable area, is characterized by a sea-level rate of 1.21 ± 0.35 mm/yr (1875–1922) that can be assumed to be a reliable estimate of the local sea-level rise during the period of interest. We compared the rate observed at Trieste with those obtained at Marina di Ravenna, 3.09 ± 0.31 mm/yr (1873–1922), and Venice, 2.05 ± 0.22 mm/yr (1873–1922). This comparison shows that the natural subsidence rate decreases from Marina di Ravenna to Venice and Trieste, turning out to be 1.88 ± 0.47 mm/yr and 0.84 ± 0.41 mm/yr at Marina di Ravenna and Venice, respectively.

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Measuring rates of present-day relative sea-level rise in low-elevation coastal zones: a critical evaluation

Ocean Science ◽

10.5194/os-15-61-2019 ◽

2019 ◽

Vol 15 (1) ◽

pp. 61-73 ◽

Cited By ~ 15

Author(s):

Molly E. Keogh ◽

Torbjörn E. Törnqvist

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Land Surface ◽

Tide Gauge ◽

Tide Gauges ◽

Coastal Zones ◽

Tide Gauge Data ◽

Relative Sea Level ◽

Gauge Data ◽

Coastal Louisiana

Abstract. Although tide gauges are the primary source of data used to calculate multi-decadal- to century-scale rates of relative sea-level change, we question the usefulness of tide-gauge data in rapidly subsiding low-elevation coastal zones (LECZs). Tide gauges measure relative sea-level rise (RSLR) with respect to the base of associated benchmarks. Focusing on coastal Louisiana, the largest LECZ in the United States, we find that these benchmarks (n=35) are anchored an average of 21.5 m below the land surface. Because at least 60 % of subsidence occurs in the top 5 m of the sediment column in this area, tide gauges in coastal Louisiana do not capture the primary contributor to RSLR. Similarly, global navigation satellite system (GNSS) stations (n=10) are anchored an average of > 14.3 m below the land surface and therefore also do not capture shallow subsidence. As a result, tide gauges and GNSS stations in coastal Louisiana, and likely in LECZs worldwide, systematically underestimate rates of RSLR as experienced at the land surface. We present an alternative approach that explicitly measures RSLR in LECZs with respect to the land surface and eliminates the need for tide-gauge data in this context. Shallow subsidence is measured by rod surface-elevation table–marker horizons (RSET-MHs) and added to measurements of deep subsidence from GNSS data, plus sea-level rise from satellite altimetry. We show that for an LECZ the size of coastal Louisiana (25 000–30 000 km2), about 40 RSET-MH instruments suffice to collect useful data. Rates of RSLR obtained from this approach are substantially higher than rates as inferred from tide-gauge data. We therefore conclude that LECZs may be at higher risk of flooding within a shorter time horizon than previously assumed.

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An Attempt to Observe Vertical Land Motion along the Norwegian Coast by CryoSat-2 and Tide Gauges

Remote Sensing ◽

10.3390/rs11070744 ◽

2019 ◽

Vol 11 (7) ◽

pp. 744 ◽

Cited By ~ 1

Author(s):

Martina Idžanović ◽

Christian Gerlach ◽

Kristian Breili ◽

Ole Andersen

Keyword(s):

Sea Level ◽

High Frequency ◽

Satellite Altimetry ◽

Tide Gauge ◽

Ice Sheets ◽

Tide Gauges ◽

Tide Gauge Data ◽

Norwegian Coast ◽

Vertical Land Motion ◽

Gauge Data

Present-day climate-change-related ice-melting induces elastic glacial isostatic adjustment (GIA) effects, while paleo-GIA effects describe the ongoing viscous response to the melting of late-Pleistocene ice sheets. The unloading initiated an uplift of the crust close to the centers of former ice sheets. Today, vertical land motion (VLM) rates in Fennoscandia reach values up to around 10 mm/year and are dominated by GIA. Uplift signals from GIA can be computed by solving the sea-level equation (SLE), S ˙ = N ˙ − U ˙ . All three quantities can also be determined from geodetic observations: relative sea-level variations ( S ˙ ) are observed by means of tide gauges, while rates of absolute sea-level change ( N ˙ ) can be observed by satellite altimetry; rates of VLM ( U ˙ ) can be determined by GPS (Global Positioning System). Based on the SLE, U ˙ can be derived by combining sea-surface measurements from satellite altimetry and relative sea-level records from tide gauges. In the present study, we have combined 7.5 years of CryoSat-2 satellite altimetry and tide-gauge data to estimate linear VLM rates at 20 tide gauges along the Norwegian coast. Thereby, we made use of monthly averaged tide-gauge data from PSMSL (Permanent Service for Mean Sea Level) and a high-frequency tide-gauge data set with 10-min sampling rate from NMA (Norwegian Mapping Authority). To validate our VLM estimates, we have compared them with the independent semi-empirical land-uplift model NKG2016LU_abs for the Nordic-Baltic region, which is based on GPS, levelling, and geodynamical modeling. Estimated VLM rates from 1 Hz CryoSat-2 and high-frequency tide-gauge data reflect well the amplitude of coastal VLM as provided by NKG2016LU_abs. We find a coastal average of 2.4 mm/year (average over all tide gauges), while NKG2016LU_abs suggests 2.8 mm/year; the spatial correlation is 0.58.

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Review article: Sea-level rise in Venice: historic and future trends

10.5194/nhess-2020-351 ◽

2020 ◽

Cited By ~ 1

Author(s):

Davide Zanchettin ◽

Sara Bruni ◽

Fabio Raicich ◽

Piero Lionello ◽

Fanny Adloff ◽

...

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Tide Gauge ◽

Tide Gauge Data ◽

Relative Sea Level ◽

Mean Sea Level ◽

The Past ◽

Gauge Data ◽

Relative Sea Level Rise ◽

Global Mean

Abstract. The City of Venice and the surrounding lagoonal ecosystem are highly vulnerable to variations in relative sea level. In the past ~150 years, this was characterized by a secular linear trend of about 2.5 mm/year resulting from the combined contributions of vertical land movement and sea-level rise. This literature review reassesses and synthesizes the progress achieved in understanding, estimating and predicting the individual contributions to local relative sea level, with focus on the most recent publications. The current best estimate of historical sea-level rise in Venice, based on tide-gauge data after removal of subsidence effects, is 1.23 ± 0.13 mm/year (period from 1872 to 2019). Subsidence thus contributed to about half of the observed relative sea-level rise over the same period. A higher – yet more uncertain – rate of sea-level rise is observed during recent decades, estimated from tide-gauge data to be about 2.76 ± 1.75 mm/year in the period 1993–2019 for the climatic component alone. An unresolved issue is the contrast between the observational capacity of tide gauges and satellite altimetry, with the latter tool not covering the Venice Lagoon. Water mass exchanges through the Gibraltar Strait currently constitute a source of substantial uncertainty for estimating future deviations of the Mediterranean mean sea-level trend from the global-mean value. Subsidence and regional atmospheric and oceanic circulation mechanisms can deviate Venetian relative sea-level trends from the global mean values for several decades. Regional processes will likely continue to determine significant interannual and interdecadal variability of Venetian sea level with magnitude comparable to that observed in the past, as well as non-negligible differential trends. Our estimate of the likely range of mean sea-level rise in Venice by 2100 due to climate change is presently estimated between 11 and 110 centimetres. An improbable yet possible high-end scenario linked to strong ice-sheet melting yields about 170 centimetres of mean sea-level rise in Venice by 2100. Projections of natural and human induced vertical land motions are currently not available, but historical evidence demonstrates that they can produce a significant contribution to the relative sea-level rise in Venice, further increasing the hazard posed by climatically-induced sea-level changes.

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