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1
de Boer, B., P. Stocchi, and R. S. W. van de Wal. "A fully coupled 3-D ice-sheet – sea-level model: algorithm and applications." Geoscientific Model Development Discussions 7, no. 3 (May 23, 2014): 3505–44. http://dx.doi.org/10.5194/gmdd-7-3505-2014.
Повний текст джерелаАнотація:
Abstract. Relative sea-level variations during the late Pleistocene cannot be reconstructed regardless of the estimates of ice-volume fluctuations. For the latter, however, the knowledge of regional and global relative sea-level variations is necessary. Overcoming this problem of circularity demands a fully coupled system where ice sheets and sea level vary consistently in space and time and dynamically affect each other. Here we present results for the past 410 000 years (410 kyr) from the coupling of a set of 3-D ice-sheet-shelf models to a global sea-level model based on the solution of gravitationally self-consistent sea-level equation. The sea-level model incorporates all the Glacial Isostatic Adjustment feedbacks for a Maxwell viscoelastic and rotating Earth model with variable coastlines. Ice volume is computed with four 3-D ice-sheet-shelf models for North America, Eurasia, Greenland and Antarctica. With an inverse approach, ice volume and temperature are derived from a benthic δ18O stacked record. The ice-sheet thickness variations are then forwarded to the sea-level model to compute the bedrock deformation, the geoid and the relative sea-level change. The latter are used to generate the new topographies for the next time step, which are forwarded to the ice-sheet models. To quantify the impact of relative sea-level variations on ice-volume evolution, we have performed coupled and uncoupled simulations. The largest differences of ice-sheet thickness change show up in the proximity of the ice-sheets edges, where relative sea-level change significantly departs from the ocean-averaged sea level variation.
2
Nakada, M., and K. Lambeck. "Glacial rebound and relative sea-level variations: a new appraisal." Geophysical Journal International 90, no. 1 (July 1, 1987): 171–224. http://dx.doi.org/10.1111/j.1365-246x.1987.tb00680.x.
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de Boer, B., P. Stocchi, and R. S. W. van de Wal. "A fully coupled 3-D ice-sheet–sea-level model: algorithm and applications." Geoscientific Model Development 7, no. 5 (September 23, 2014): 2141–56. http://dx.doi.org/10.5194/gmd-7-2141-2014.
Повний текст джерелаАнотація:
Abstract. Relative sea-level variations during the late Pleistocene can only be reconstructed with the knowledge of ice-sheet history. On the other hand, the knowledge of regional and global relative sea-level variations is necessary to learn about the changes in ice volume. Overcoming this problem of circularity demands a fully coupled system where ice sheets and sea level vary consistently in space and time and dynamically affect each other. Here we present results for the past 410 000 years (410 kyr) from the coupling of a set of 3-D ice-sheet-shelf models to a global sea-level model, which is based on the solution of the gravitationally self-consistent sea-level equation. The sea-level model incorporates the glacial isostatic adjustment feedbacks for a Maxwell viscoelastic and rotating Earth model with coastal migration. Ice volume is computed with four 3-D ice-sheet-shelf models for North America, Eurasia, Greenland and Antarctica. Using an inverse approach, ice volume and temperature are derived from a benthic δ18O stacked record. The derived surface-air temperature anomaly is added to the present-day climatology to simulate glacial–interglacial changes in temperature and hence ice volume. The ice-sheet thickness variations are then forwarded to the sea-level model to compute the bedrock deformation, the change in sea-surface height and thus the relative sea-level change. The latter is then forwarded to the ice-sheet models. To quantify the impact of relative sea-level variations on ice-volume evolution, we have performed coupled and uncoupled simulations. The largest differences of ice-sheet thickness change occur at the edges of the ice sheets, where relative sea-level change significantly departs from the ocean-averaged sea-level variations.
4
Oelsmann, Julius, Marta Marcos, Marcello Passaro, Laura Sanchez, Denise Dettmering, Sönke Dangendorf, and Florian Seitz. "Regional variations in relative sea-level changes influenced by nonlinear vertical land motion." Nature Geoscience 17, no. 2 (February 2024): 137–44. http://dx.doi.org/10.1038/s41561-023-01357-2.
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AbstractVertical land movements can cause regional relative sea-level changes to differ substantially from climate-driven absolute sea-level changes. Whereas absolute sea level has been accurately monitored by satellite altimetry since 1992, there are limited observations of vertical land motion. Vertical land motion is generally modelled as a linear process, despite some evidence of nonlinear motion associated with tectonic activity, changes in surface loading or groundwater extraction. As a result, the temporal evolution of vertical land motion, and its contribution to projected sea-level rise and its uncertainty, remains unresolved. Here we generate a probabilistic vertical land motion reconstruction from 1995 to 2020 to determine the impact of regional-scale and nonlinear vertical land motion on relative sea-level projections up to 2150. We show that regional variations in projected coastal sea-level changes are equally influenced by vertical land motion and climate-driven processes, with vertical land motion driving relative sea-level changes of up to 50 cm by 2150. Accounting for nonlinear vertical land motion increases the uncertainty in projections by up to 1 m on a regional scale. Our results highlight the uncertainty in future coastal impacts and demonstrate the importance of including nonlinear vertical land motions in sea-level change projections.
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Novita, Eva, Masita Dwi Mandini Manessa, and Mufti Petala Patria. "Relative and Absolute Sea Level Change Variability in The Palabuhanratu Bay Waters." IOP Conference Series: Earth and Environmental Science 1275, no. 1 (November 1, 2023): 012015. http://dx.doi.org/10.1088/1755-1315/1275/1/012015.
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Abstract SLR could affect the waters of Palabuhanratu Bay, which are exposed to the Indian Ocean. Sea levels are rising due to RSL and ASL changes. RSL has increased by 22.86 mm/year based on tidal data for 2013–2022. In contrast, ASL has increased by 4.48 mm/year based on satellite altimetry data for 1992–2022. The research uses the linear regression method to get the SLR value. According to earlier studies, dynamic change elements connected to alterations in the atmosphere and ocean circulation are typically considered when analyzing sea level variations. This work explores sea-level variations, including dynamic and static changes impacted by geological processes like deformation. Dynamic change factors, such as climate anomalies, ENSO, and IOD, affect these changes. Regarding RSL changes, ENSO has a more decisive influence than IOD, and vice versa for ASL changes. In the La Nina phenomenon and negative IOD phase, RSL and ASL trend changes are enhanced, whereas they are lowered in the El Nino and positive IOD phases. These waters’ sea-level variations are only slightly impacted by local processes, such as VLM. It has a more decisive influence on RSL changes than ASL.
6
Sultan, S. A. R., F. Ahmad, and D. Nassar. "Relative Contribution of External Sources of Mean Sea-level Variations at Port Sudan, Red Sea." Estuarine, Coastal and Shelf Science 42, no. 1 (January 1996): 19–30. http://dx.doi.org/10.1006/ecss.1996.0002.
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Mitrovica, J. X., and W. R. Peltier. "Constraints on mantle viscosity from relative sea level variations in Hudson Bay." Geophysical Research Letters 19, no. 12 (June 19, 1992): 1185–88. http://dx.doi.org/10.1029/92gl01285.
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Pereira, Elizabeth Santos, Jhone Araújo, Kátia Mansur, Kita Macario, Eduardo Q. Alves, and Fábio Ferreira Dias. "Variations in relative sea level in south America, Brazil: A comprehensive analysis." Quaternary Science Advances 12 (October 2023): 100116. http://dx.doi.org/10.1016/j.qsa.2023.100116.
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Zanchettin, Davide, Sara Bruni, Fabio Raicich, Piero Lionello, Fanny Adloff, Alexey Androsov, Fabrizio Antonioli, et al. "Sea-level rise in Venice: historic and future trends (review article)." Natural Hazards and Earth System Sciences 21, no. 8 (September 1, 2021): 2643–78. http://dx.doi.org/10.5194/nhess-21-2643-2021.
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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 an average rate of relative sea-level rise 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 quantification, understanding and prediction of the individual contributions to local relative sea level, with a focus on the most recent studies. Subsidence contributed to about half of the historical relative sea-level rise in Venice. The current best estimate of the average rate of sea-level rise during the observational period from 1872 to 2019 based on tide-gauge data after removal of subsidence effects is 1.23 ± 0.13 mm/year. A higher – but more uncertain – rate of sea-level rise is observed for more recent years. Between 1993 and 2019, an average change of about +2.76 ± 1.75 mm/year is estimated from tide-gauge data after removal of subsidence. Unfortunately, satellite altimetry does not provide reliable sea-level data within the Venice Lagoon. Local sea-level changes in Venice closely depend on sea-level variations in the Adriatic Sea, which in turn are linked to sea-level variations in the Mediterranean Sea. Water mass exchange through the Strait of Gibraltar and its drivers currently constitute a source of substantial uncertainty for estimating future deviations of the Mediterranean mean sea-level trend from the global-mean value. Regional atmospheric and oceanic processes will likely contribute significant interannual and interdecadal future variability in Venetian sea level with a magnitude comparable to that observed in the past. On the basis of regional projections of sea-level rise and an understanding of the local and regional processes affecting relative sea-level trends in Venice, the likely range of atmospherically corrected relative sea-level rise in Venice by 2100 ranges between 32 and 62 cm for the RCP2.6 scenario and between 58 and 110 cm for the RCP8.5 scenario, respectively. A plausible but unlikely high-end scenario linked to strong ice-sheet melting yields about 180 cm of relative sea-level rise in Venice by 2100. Projections of human-induced vertical land motions are currently not available, but historical evidence demonstrates that they have the potential to produce a significant contribution to the relative sea-level rise in Venice, exacerbating the hazard posed by climatically induced sea-level changes.
10
Bills, Bruce G., and Thomas S. James. "Late Quaternary variations in relative sea level due to glacial cycle polar wander." Geophysical Research Letters 23, no. 21 (October 15, 1996): 3023–26. http://dx.doi.org/10.1029/96gl02886.
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Okuno, Jun'ichi, and Hideki Miura. "Last deglacial relative sea level variations in Antarctica derived from glacial isostatic adjustment modelling." Geoscience Frontiers 4, no. 6 (November 2013): 623–32. http://dx.doi.org/10.1016/j.gsf.2012.11.004.
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Hegewald, Anne, and Wilfried Jokat. "Relative sea level variations in the Chukchi region - Arctic Ocean - since the late Eocene." Geophysical Research Letters 40, no. 5 (March 6, 2013): 803–7. http://dx.doi.org/10.1002/grl.50182.
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Gargani, Julien. "Influence of Relative Sea-Level Rise, Meteoric Water Infiltration and Rock Weathering on Giant Volcanic Landslides." Geosciences 13, no. 4 (April 6, 2023): 113. http://dx.doi.org/10.3390/geosciences13040113.
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Recent studies have shown that giant landslides correlate with climatic variations. However, the precise processes involved in this phenomenon need to be better defined. This study investigates the causes of giant landslides using a modeling approach. Here, I show that the effect of meteoric water infiltration could be distinguished from that of the sea level rise in triggering paleo-landslides. It is possible to identify the cause of coastal paleo-landslides based on the age of occurrence and comparison with climatic signals when glacial maxima are wetter than during interglacial periods, as in Polynesia and East Equatorial Africa, but not in other cases (Caribbean, Indonesia). The role of pore-pressure variations and sea water loading variations is discussed. The interaction between the relative sea level rise, pre-existing relief and deep weak structure due to the presence of highly weathered lavas may trigger the conditions for a large landslide. Highly weathered lavas have very low friction angles in volcanic islands. When volcanoes are still active, pressure fluctuations in the magma chamber caused by sea level lowering are expected to play a significant role in the destabilization of the relief. Competing processes in real cases make it difficult to distinguish between these processes.
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Hamlington, Benjamin D., Christopher G. Piecuch, John T. Reager, Hrishi Chandanpurkar, Thomas Frederikse, R. Steven Nerem, John T. Fasullo, and Se-Hyeon Cheon. "Origin of interannual variability in global mean sea level." Proceedings of the National Academy of Sciences 117, no. 25 (June 8, 2020): 13983–90. http://dx.doi.org/10.1073/pnas.1922190117.
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The two dominant drivers of the global mean sea level (GMSL) variability at interannual timescales are steric changes due to changes in ocean heat content and barystatic changes due to the exchange of water mass between land and ocean. With Gravity Recovery and Climate Experiment (GRACE) satellites and Argo profiling floats, it has been possible to measure the relative steric and barystatic contributions to GMSL since 2004. While efforts to “close the GMSL budget” with satellite altimetry and other observing systems have been largely successful with regards to trends, the short time period covered by these records prohibits a full understanding of the drivers of interannual to decadal variability in GMSL. One particular area of focus is the link between variations in the El Niño−Southern Oscillation (ENSO) and GMSL. Recent literature disagrees on the relative importance of steric and barystatic contributions to interannual to decadal variability in GMSL. Here, we use a multivariate data analysis technique to estimate variability in barystatic and steric contributions to GMSL back to 1982. These independent estimates explain most of the observed interannual variability in satellite altimeter-measured GMSL. Both processes, which are highly correlated with ENSO variations, contribute about equally to observed interannual GMSL variability. A theoretical scaling analysis corroborates the observational results. The improved understanding of the origins of interannual variability in GMSL has important implications for our understanding of long-term trends in sea level, the hydrological cycle, and the planet’s radiation imbalance.
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YBERT, JEAN-PIERRE, WALTER MARESCHI BISSA, and MIRYAN KUTNER. "Relative Sea Level Variations and Climatic Evolutuion in Southeastern and Southern Brazil During the Late Holocene." Pesquisas em Geociências 28, no. 2 (December 31, 2001): 75. http://dx.doi.org/10.22456/1807-9806.20270.
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Analysis of organic sediments from a swamp forest on the coastal plain of São Paulo State (southeastern Brazil) has been carried out. Diatom and pollen contents from the same samples were analysed. This study allowed reconstruction of the regional paleoenvironment during the Late Holocene. From at least 4400 to 3250 yr BP the site was a lagoon surrounded by a relatively open forest. At ca. 3250 yr BP, after the retreat of the sea, a swamp forest occupied the area. This swamp forest remains until the present day. It was locally altered during a short period between ca. 1400 and 775 yr BP when, due to a rise in groundwater, a fresh water lake or marsh was formed. The climate was similar to the present during the whole Late Holocene, except for three slightly more humid episodes: 3250-2600, around 2000, and 1400-775 yr BP. No human impact on the vegetation was recorded during the Late Holocene. Our results show that sea level was higher than the present zero level from 4400 to 3250 yr BP, contradicting a widely accepted relative sea level trend that suggests that at least two important negative sea level oscillations occurred during the Holocene (4100-3800 and 3000-2700 yr BP). Conversely, these results tend to confirm more recent studies that propose a continuously declining relative sea level trend. Comparison of our data with those from 24 sites situated in southeastern, southern and central Brazil show that the more humid episodes recorded at Cananéia-Iguape might be correlated with El Niño like events. Trends in climatic evolution during the Late Holocene are opposite at north and south of 20ºS latitude.
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Shelekhova, T. S., N. B. Lavrova, and Yu S. Tikhonova. "Relative sea-level variations indicated by micropaleontological data from small lake bottom sediments (Kandalaksha Bay, NW Russia)." Limnology and Freshwater Biology, no. 4 (2022): 1580–82. http://dx.doi.org/10.31951/2658-3518-2022-a-4-1580.
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Abstract. The results of the micro-paleontological study of bottom sediments from a small lake on the Kandalaksha Bay shore of the White Sea are reported. Three stages in the evolution of the lake basin: marine, transitional and lacustrine were recognized. The characteristics of their diatom complexes and palynological spectra were revealed. Marine-facies sediments were shown to be dominated by poly- and mesohalobes, their share in the transition facies is twice as small, and freshwater diatom complexes contain up to 10% halophiles. Facies were shown to be reliably identified, using the pollen and spores of distinctive species indicative of certain ecological conditions. Non-pollen palynomorphs (algae Pediastrum, Botryococcus and sponge spicules) can be used for identifying various facies. These data will be used later to more reliably and objectively reconstruct variations in relative sea level and the sea shoreline migration in the Holocene. A decrease in sea level was established at the turn of 7200 cal. years and the isolation of the lake from the sea occurred about 6700 cal. years ago.
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Holland, Steven M., and Max Christie. "Changes in area of shallow siliciclastic marine habitat in response to sediment deposition: implications for onshore-offshore paleobiologic patterns." Paleobiology 39, no. 4 (2013): 511–24. http://dx.doi.org/10.1666/12053.
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Models presented here of shallow-marine siliciclastic deposition show that the widths of depth-defined regions differ markedly in response to sea-level change. These models add to recent studies that have emphasized the highly specific response of habitat area to sea-level change. Collectively, these studies indicate that a particular bathymetric zone on a particular margin may vary substantially in area during a sea-level change, while other such zones and margins may experience little or even opposite responses. In the models presented here, intermediate-depth and deep-water regions tend to show sinusoidal variations in width, with widening during relative falls in sea level and narrowing during relative rises. The shallow-water region displays markedly non-sinusoidal change and is consistently characterized by abrupt widening at the beginning of the highstand systems tract and an equally abrupt narrowing at the onset of sea-level fall at the beginning of the falling-stage systems tract. These onshore-offshore differences in how width and area change with sea level may explain why taxa in shallow-water settings tend to be more abundant, eurytopic, and widespread than those in deeper-water settings. Likewise, these models suggest that the evolution of novelty in nearshore habitats may be a response to wide variation in shallow-marine area during sea-level change.
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Iz, H. Bâki, C. K. Shum, and T. Y. Yang. "Conflation of satellite altimetry and tide gauge records at coast." Journal of Geodetic Science 10, no. 1 (October 27, 2020): 62–68. http://dx.doi.org/10.1515/jogs-2020-0113.
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AbstractThis study demonstrates that absolute (geocentric) and relative sea level trends, sea level acceleration, low frequency sea level variations and linear trends in vertical crustal movements experienced at a tide gauge station can be estimated simultaneously using conflated satellite altimetry and tide gauge measurements without the aid of GPS measurements. The formulation is the first of its kind in sea level studies and its effectiveness is exemplified using tide gauge, and satellite altimetry measurements carried out in the vicinity of a tide gauge station.
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Ballu, Valérie, Médéric Gravelle, Guy Wöppelmann, Olivier de Viron, Paul Rebischung, Mélanie Becker, and Pierre Sakic. "Vertical land motion in the Southwest and Central Pacific from available GNSS solutions and implications for relative sea levels." Geophysical Journal International 218, no. 3 (May 27, 2019): 1537–51. http://dx.doi.org/10.1093/gji/ggz247.
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SUMMARY Coastal populations are impacted by relative sea level variations, which consist both of absolute sea level variations and of vertical land motions. This paper focuses on the Southwest and Central Pacific region, a recognized vulnerable region to sea level rise and where a large range of vertical land motion dynamics is observed. We analyse vertical displacement rates obtained from Global Navigation Satellite Systems (GNSS) by different analysis centres. We study the role played by modelled parameters, such as step discontinuities (due to equipment changes, earthquakes, etc.), in the position time-series analysis. We propose a new modelling approach based on a joint inversion of GNSS position time-series from different analysis centres. The final uncertainty on the vertical land motion rates is estimated as a combination of the uncertainty due to the GNSS data processing itself and the uncertainty due to the stability of the reference frame in which the GNSS data are expressed. We find that the dominant trend in the Southwest and Central Pacific is a moderate subsidence, with an average rate of −1.1 mm yr–1, but significant variations are observed, with displacement rates varying from an uplift of 1.6 ± 0.3 mm yr–1 to a subsidence of −5.4 ± 0.3 mm yr–1. Taking into account the geodynamic context, we assess, for each station, the relevance of current estimates of linear vertical displacement rate and uncertainty for forecasting future coastal sea levels.
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Kayanne, Hajime, Teruaki Ishii, Eiji Matsumoto, and Nobuyuki Yonekura. "Late Holocene Sea-Level Change on Rota and Guam, Mariana Islands, and Its Constraint on Geophysical Predictions." Quaternary Research 40, no. 2 (September 1993): 189–200. http://dx.doi.org/10.1006/qres.1993.1071.
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AbstractHolocene emergent reefs and notches are well distributed on Rota and Guam. Relative sea-level changes at these islands are reconstructed based on geomorphological observations and borings on present and emergent reefs, together with 54 radiocarbon dates. Sea level rose gradually to a maximum of 1.8 m between 6000 and 4200 yr B.P. and reached its highest level by 4200 yr B.P. on both islands. After 3200 yr B.P. abrupt uplift caused emergence of the reef. By subtracting the tectonic effect, we obtained the sea-level change in the Marianas: sea level reached its present level by 4200 yr B.P. and has remained almost stable since then. Reconstructed late Holocene sea-level change in the Mariana Islands provides constraints on geophysical models of sea-level variations.
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Machado, Giseli Modolo Vieira, Alex Cardoso Bastos, Alex da Silva de Freitas, and Jose Antônio Baptista Neto. "Sedimentary, Geochemical and Micropaleontological Responses to Sea Level Variations in the Vitoria Estuary, Espírito Santo." Radiocarbon 60, no. 2 (March 6, 2018): 583–600. http://dx.doi.org/10.1017/rdc.2018.5.
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AbstractMarine insertion indicators in the Vitoria estuary (ES) revealed relative variations in sea level during the Holocene in three sediment cores. Sedimentological, geochemical (C/N ratio), and paleontological (shells and palynomorphs) analysis and 14C dating associated five sedimentary facies to different estuarine deposits. A C/N ratio <10 at the core base indicated organic matter of marine origin. Moving up the cores to 110–150 cm, an abrupt increase in C/N to 26–63 in every core suggests the sudden entry of higher plants into the estuary, potentially the moment sea level retreated. High continental (10,743 palynomorphs/g) and low marine palynomorph concentrations (323 palynomorphs/g) suggest a primarily continental source even during transgression and at high sea level. Around 8973 cal BP, an open bay already existed in the region of Vitoria. Sea level potentially exceeded the current level around 7110 cal BP. The transgressive maximum was at 5567 cal BP. Marine insertion indicators, such as marine shells, low C/N ratios and foraminiferal linings, did not always respond directly to sea level oscillations. These discrepancies probably result from lateral variations in sedimentary deposits from transport patterns and from variations in organic matter and palynomorph preservation due to differences in river and obstacle proximity.
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Leijala, Ulpu, Jan-Victor Björkqvist, Milla M. Johansson, Havu Pellikka, Lauri Laakso, and Kimmo K. Kahma. "Combining probability distributions of sea level variations and wave run-up to evaluate coastal flooding risks." Natural Hazards and Earth System Sciences 18, no. 10 (October 24, 2018): 2785–99. http://dx.doi.org/10.5194/nhess-18-2785-2018.
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Abstract. Tools for estimating probabilities of flooding hazards caused by the simultaneous effect of sea level and waves are needed for the secure planning of densely populated coastal areas that are strongly vulnerable to climate change. In this paper we present a method for combining location-specific probability distributions of three different components: (1) long-term mean sea level change, (2) short-term sea level variations and (3) wind-generated waves. We apply the method at two locations in the Helsinki archipelago to obtain total water level estimates representing the joint effect of the still water level and the wave run-up for the present, 2050 and 2100. The variability of the wave conditions between the study sites leads to a difference in the safe building levels of up to 1 m. The rising mean sea level in the Gulf of Finland and the uncertainty related to the associated scenarios contribute notably to the total water levels for the year 2100. A test with theoretical wave run-up distributions illustrates the effect of the relative magnitude of the sea level variations and wave conditions on the total water level. We also discuss our method's applicability to other coastal regions.
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Pajak, Katarzyna, Kamil Kowalczyk, Jānis Kaminskis, and Magdalena Idzikowska. "Studying the Sensitivity of Satellite Altimetry, Tide Gauge and GNSS Observations to Changes in Vertical Displacements." Geomatics and Environmental Engineering 15, no. 4 (September 17, 2021): 45–58. http://dx.doi.org/10.7494/geom.2021.15.4.45.
Повний текст джерелаАнотація:
Tide gauge observations provide sea level relative to the Earth’s crust, while satellite altimetry measures sea level variations relative to the centre of the Earth’s mass. Local vertical land motion can be a significant contribution to the measured sea level change.Satellite altimetry was traditionally used to study the open ocean, but this technology is now being used over inland seas too.The difference of both observations can be used to estimate vertical crustal movement velocities along the sea coast. In this paper, vertical crustal movement velocities were investigated at tide gauge sites along the Adriatic Sea coast by analyzing differences between Tide Gauge (TG) and Satellite Altimetry (SA) observations. Furthermore, the estimated vertical motion rates were compared with those from nearby GNSS measurements.The study determines the practical relationships between these vertical crustal movements and those determined from unrelated data acquired from the neighbouring GNSS stations. The results show general consistence with the present geodynamics in the Adriatic Sea coastal zone.
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Meyssignac, B., X. Fettweis, R. Chevrier, and G. Spada. "Regional Sea Level Changes for the Twentieth and the Twenty-First Centuries Induced by the Regional Variability in Greenland Ice Sheet Surface Mass Loss." Journal of Climate 30, no. 6 (March 1, 2017): 2011–28. http://dx.doi.org/10.1175/jcli-d-16-0337.1.
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Abstract Surface mass balance (SMB) variations of the Greenland ice sheet (GrIS) have been identified as an important contributor to contemporary and projected global mean sea level variations, but their impact on the regional sea level change pattern is still poorly known. This study proposes estimates of GrIS SMB over 1900–2100 based on the output of 32 atmosphere–ocean general circulation models and Earth system models involved in phase 5 of the Climate Model Intercomparison Project (CMIP5). It is based on a downscaling technique calibrated against the Modèle Atmosphérique Régional (MAR) regional climate model and it provides an ensemble of 32 Greenland SMB estimates for each Greenland major drainage basin. Because the GrIS SMB does not respond uniformly to greenhouse gas (GHG) emissions, the southern part of the GrIS is more sensitive to climate warming. This study shows that this part should be in imbalance in the twenty-first century sooner than the northern part. This regional variability significantly affects the associated relative sea level pattern over the entire ocean and particularly along the U.S. East Coast and the northern coast of Europe. This highlights the necessity of taking into account GrIS regional SMB changes to evaluate accurately relative sea level changes in future projections.
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Weisse, Ralf, Inga Dailidienė, Birgit Hünicke, Kimmo Kahma, Kristine Madsen, Anders Omstedt, Kevin Parnell, et al. "Sea level dynamics and coastal erosion in the Baltic Sea region." Earth System Dynamics 12, no. 3 (August 17, 2021): 871–98. http://dx.doi.org/10.5194/esd-12-871-2021.
Повний текст джерелаАнотація:
Abstract. There are a large number of geophysical processes affecting sea level dynamics and coastal erosion in the Baltic Sea region. These processes operate on a large range of spatial and temporal scales and are observed in many other coastal regions worldwide. This, along with the outstanding number of long data records, makes the Baltic Sea a unique laboratory for advancing our knowledge on interactions between processes steering sea level and erosion in a climate change context. Processes contributing to sea level dynamics and coastal erosion in the Baltic Sea include the still ongoing viscoelastic response of the Earth to the last deglaciation, contributions from global and North Atlantic mean sea level changes, or contributions from wind waves affecting erosion and sediment transport along the subsiding southern Baltic Sea coast. Other examples are storm surges, seiches, or meteotsunamis which primarily contribute to sea level extremes. Such processes have undergone considerable variation and change in the past. For example, over approximately the past 50 years, the Baltic absolute (geocentric) mean sea level has risen at a rate slightly larger than the global average. In the northern parts of the Baltic Sea, due to vertical land movements, relative mean sea level has decreased. Sea level extremes are strongly linked to variability and changes in large-scale atmospheric circulation. The patterns and mechanisms contributing to erosion and accretion strongly depend on hydrodynamic conditions and their variability. For large parts of the sedimentary shores of the Baltic Sea, the wave climate and the angle at which the waves approach the nearshore region are the dominant factors, and coastline changes are highly sensitive to even small variations in these driving forces. Consequently, processes contributing to Baltic sea level dynamics and coastline change are expected to vary and to change in the future, leaving their imprint on future Baltic sea level and coastline change and variability. Because of the large number of contributing processes, their relevance for understanding global figures, and the outstanding data availability, global sea level research and research on coastline changes may greatly benefit from research undertaken in the Baltic Sea.
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Makaroğlu, Özlem, Norbert R. Nowaczyk, Kadir K. Eriş, and M. Namık Çağatay. "High-resolution palaeomagnetic record from Sea of Marmara sediments for the last 70 ka." Geophysical Journal International 222, no. 3 (June 5, 2020): 2024–39. http://dx.doi.org/10.1093/gji/ggaa281.
Повний текст джерелаАнотація:
SUMMARY Magnetostratigraphic and geochemical analyses were performed on two sediment cores recovered from the Sea of Marmara to investigate geomagnetic field variations over the last 70 ka. A chronology for each of the two cores was developed from eight AMS 14C datings, tephrochronology, and tuning of Ca concentrations with stadials and interstadials observed in Greenland ice core oxygen isotope data. Based on the age models, cores MD01–2430 and MRS-CS19 reach back to 70 and 32 ka, respectively. High average sedimentation rates of 43 cm kyr–1 for core MD01–2430 and 68 cm kyr–1 for core MRS-CS19 allow high-resolution reconstruction of geomagnetic field variations for the Sea of Marmara. Mineral magnetic properties are sensitive to glacioeustatic sea level changes and palaeoclimate variations in this region, reflecting the variable palaeoenvironmental conditions of the Sea of Marmara during last 70 ka. Despite the impairment of the palaeomagnetic record in some stratigraphic intervals due to early diagenesis, relative palaeointensity variations in the Sea of Marmara sediments correlate well with similar records derived from other regions, such as the nearby Black Sea and the GLOPIS-75 stack. The directional record derived from the Sea of Marmara cores exhibits typical palaeosecular variation patterns, with directional anomalies at 41 and 18 ka, representing the Laschamps and postulated Hilina Pali excursions, respectively. Both directional anomalies are also associated with palaeointensity minima. A further palaeointensity minimum at 34.5 ka is likely related to the Mono Lake excursion, with no directional deviation documented in the Sea of Marmara palaeomagnetic record so far.
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Surić, Maša. "Rekonstruiranje promjena morske razine na istočnoj obali Jadrana (Hrvatska) – pregled." Geoadria 14, no. 2 (January 11, 2017): 181. http://dx.doi.org/10.15291/geoadria.550.
Повний текст джерелаАнотація:
Rocky karstified coast, low tidal range, indented shoreline with numerous islands, diverse coastal biocenoses, abundant palaeontological, archaeological and historical evidence, relatively dense tide-gauge stations and developing GPS network – all these facts offer optimal prerequisite for the sea-level changes studies on the Croatian coast. Through various methodological approaches (geomorphological, biostratigraphical, archaeological/historical, mareographic, geodetic, radiometric), most of these issues have been used in order to reconstruct relative sea and land motions, yielding scattered and sometimes erroneous results. Unfortunately, some of them have been often uncritically used as the basis for the subsequent research. Only recently, with multidisciplinary approach, sequences of relative sea-level variations have been successfully revealed, but opportunities that eastern Adriatic coast offers will, undoubtedly, ensure relatively rapid research progress.
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Thompson, Philip R., Mark A. Merrifield, Judith R. Wells, and Chantel M. Chang. "Wind-Driven Coastal Sea Level Variability in the Northeast Pacific." Journal of Climate 27, no. 12 (June 5, 2014): 4733–51. http://dx.doi.org/10.1175/jcli-d-13-00225.1.
Повний текст джерелаАнотація:
Abstract The rate of coastal sea level change in the northeast Pacific (NEP) has decreased in recent decades. The relative contributions to the decreased rate from remote equatorial wind stress, local longshore wind stress, and local windstress curl are examined. Regressions of sea level onto wind stress time series and comparisons between NEP and Fremantle sea levels suggest that the decreased rate in the NEP is primarily due to oceanic adjustment to strengthened trade winds along the equatorial and coastal waveguides. When taking care to account for correlations between the various wind stress time series, the roles of longshore wind stress and local windstress curl are found to be of minor importance in comparison to equatorial forcing. The predictability of decadal sea level change rates along the NEP coastline is therefore largely determined by tropical variability. In addition, the importance of accounting for regional, wind-driven sea level variations when attempting to calculate accelerations in the long-term rate of sea level rise is demonstrated.
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Gomez, Natalya, Konstantin Latychev, and David Pollard. "A Coupled Ice Sheet–Sea Level Model Incorporating 3D Earth Structure: Variations in Antarctica during the Last Deglacial Retreat." Journal of Climate 31, no. 10 (April 26, 2018): 4041–54. http://dx.doi.org/10.1175/jcli-d-17-0352.1.
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Abstract A gravitationally self-consistent, global sea level model with 3D viscoelastic Earth structure is interactively coupled to a 3D dynamic ice sheet model, and the coupled model is applied to simulate the evolution of ice cover, sea level changes, and solid Earth deformation over the last deglaciation, from 40 ka to the modern. The results show that incorporating lateral variations in Earth’s structure across Antarctica yields local differences in the modeled ice history and introduces significant uncertainty in estimates of both relative sea level change and modern crustal motions through the last deglaciation. An analysis indicates that the contribution of glacial isostatic adjustment to modern records of sea level change and solid Earth deformation in regions of Antarctica underlain by low mantle viscosity may be more sensitive to ice loading during the late Holocene than across the last deglaciation.
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Antonioli, Fabrizio, Stefano Furlani, Paolo Montagna, Paolo Stocchi, Lucio Calcagnile, Gianluca Quarta, Jonathan Cecchinel, et al. "Submerged Speleothems and Sea Level Reconstructions: A Global Overview and New Results from the Mediterranean Sea." Water 13, no. 12 (June 14, 2021): 1663. http://dx.doi.org/10.3390/w13121663.
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This study presents a global overview of the submerged speleothems used to reconstruct paleo sea levels and reports new results from two stalactites collected in the Mediterranean Sea. Coastal cave deposits significantly contributed to the understanding of global and regional sea-level variations during the Middle and Late Quaternary. The studied speleothems cover the last 1.4 Myr and focused mainly on Marine Isotope Stages (MIS) 1, 2, 3, 5.1, 5.3, 5.5, 7.1, 7.2, 7.3 and 7.5. The results indicate that submerged speleothems represent extraordinary archives that can provide detailed information on former sea-level changes. The two stalactites collected in the central Mediterranean Sea, at Favignana and Ustica islands (Sicily, Italy), are both characterized by continental, phreatic or marine layers. The U-Th and 14C ages of the new speleothems provide results of great interest for relative sea-level changes over the last 1000 years.
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Araújo, Maria da Assunção. "Climate, tectonics and beach erosion: the case of Espinho (NW Portuguese coast)." Estudos do Quaternário / Quaternary Studies, no. 5 (June 21, 2018): 39–50. http://dx.doi.org/10.30893/eq.v0i5.59.
Повний текст джерелаАнотація:
Sea level is a very changeable surface. Furthermore, the land may also be moving, in a slower rate,generating relative sea level changes. The causes of relative sea level changes are variable, but the onesthat cause more intense variations are related to climate.During Little Ice Age (LIA) Northern Hemisphere's summer temperatures fell significantly below theAD 1961–1990 range. This climate situation was responsible for a greater discharge of rivers, whichcould lead to a greater transportation of sediments to the coastline. During these cold periods, sea levelwas lower than in present time. All this could imply a coastline progradation, with the successiveabandon of older beach ridges, reinforcing the sandy supply for dune building. The coastal situationshould be, in some sense, the opposite of the situations that we face today.In present warm period, rivers carry less sediment than during LIA. Moreover, the recent sea level risecontributes to a coastal migration inlands and the erosion of previous beaches and dunes.Our investigation on ancient marine levels and Holocene cemented dunes suggests that the area nearEsmoriz (20 km south of Porto, NW Portuguese coast) is probably subsiding. This possible subsidence,together with recent sea level rise, induced by the end of LIA, could explain the severe coastal erosionthat is taking place at Espinho area (15 km south of Porto) since the middle of the XIX century.This example shows clearly the complexity of relative sea-level changes. Because of this complexity,sea level curves are not similar worldwide, as they depend on the interference of multiple time-scalesphenomena.
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Enzel, Yehouda, Revital Bookman (Ken Tor), David Sharon, Haim Gvirtzman, Uri Dayan, Baruch Ziv, and Mordechai Stein. "Late Holocene climates of the Near East deduced from Dead Sea level variations and modern regional winter rainfall." Quaternary Research 60, no. 3 (July 2003): 263–73. http://dx.doi.org/10.1016/j.yqres.2003.07.011.
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AbstractThe Dead Sea is a terminal lake of one of the largest hydrological systems in the Levant and may thus be viewed as a large rain gauge for the region. Variations of its level are indicative of the climate variations in the region. Here, we present the decadal- to centennial-resolution Holocene lake-level curve of the Dead Sea. Then we determine the regional hydroclimatology that affected level variations. To achieve this goal we compare modern natural lake-level variations and instrumental rainfall records and quantify the hydrology relative to lake-level rise, fall, or stability. To quantify that relationship under natural conditions, rainfall data pre-dating the artificial Dead Sea level drop since the 1960s are used. In this respect, Jerusalem station offers the longest uninterrupted pre-1960s rainfall record and Jerusalem rains serve as an adequate proxy for the Dead Sea headwaters rainfall. Principal component analysis indicates that temporal variations of annual precipitation in all stations in Israel north of the current 200 mm yr−1 average isohyet during 1940–1990 are largely synchronous and in phase (∼70% of the total variance explained by PC1). This station also represents well northern Jordan and the area all the way to Beirut, Lebanon, especially during extreme drought and wet spells. We (a) determine the modern, and propose the past regional hydrology and Eastern Mediterranean (EM) climatology that affected the severity and length of droughts/wet spells associated with multiyear episodes of Dead Sea level falls/rises and (b) determine that EM cyclone tracks were different in average number and latitude in wet and dry years in Jerusalem. The mean composite sea level pressure and 500-mb height anomalies indicate that the potential causes for wet and dry episodes span the entire EM and are rooted in the larger-scale northern hemisphere atmospheric circulation. We also identified remarkably close association (within radiocarbon resolution) between climatic changes in the Levant, reflected by level changes, and culture shifts in this region.
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Oldale, Robert N., Steven M. Colman, and Glen A. Jones. "Radiocarbon Ages from Two Submerged Strandline Features in the Western Gulf of Maine and a Sea-Level Curve for the Northeastern Massachusetts Coastal Region." Quaternary Research 40, no. 1 (July 1993): 38–45. http://dx.doi.org/10.1006/qres.1993.1054.
Повний текст джерелаАнотація:
AbstractNew radiocarbon dates provide ages for two submerged strandline features on the Massachusetts inner shelf. These ages provide limited control on a relative sea-level (RSL) curve for the late Wisconsinan and Holocene. The curve indicates a late Wisconsinan high stand of RSL of +33 m about 14,000 yr ago and a very short-lived relative low stand of about -43 m at about 12,000 yr ago followed by a rise to present sea level. Rapid changes of RSL around 12,000 yr ago may be related to changes in global glacial meltwater discharge and eustatic sea-level change shown by dated corals off Barbados. Variations in the magnitude and timing of RSL change from south to north along the coast of the western Gulf of Maine are due to greater crustal depression and later deglaciation to the north.
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Avşar, Nevin, and Şenol Kutoğlu. "Recent Sea Level Change in the Black Sea from Satellite Altimetry and Tide Gauge Observations." ISPRS International Journal of Geo-Information 9, no. 3 (March 24, 2020): 185. http://dx.doi.org/10.3390/ijgi9030185.
Повний текст джерелаАнотація:
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.
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Steffen, H., P. Wu, and H. Wang. "Optimal locations of sea-level indicators in glacial isostatic adjustment investigations." Solid Earth Discussions 5, no. 2 (December 18, 2013): 2419–48. http://dx.doi.org/10.5194/sed-5-2419-2013.
Повний текст джерелаАнотація:
Abstract. Fréchet (sensitivity) kernels are an important tool in glacial isostatic adjustment (GIA) investigations to understand lithospheric thickness, mantle viscosity and ice-load model variations. These parameters influence the interpretation of geologic, geophysical and geodetic data, which contribute to our understanding of global change. Recently, sensitivity kernels have been extended to laterally heterogeneous Earth models using the finite-element formulation, which enabled detailed studies on the sensitivity of the different geodetic observations of GIA such as GPS and terrestrial and space gravimetry. In this study, we discuss global sensitivities of relative sea-level (RSL) data of the last 18 000 yr. This also includes indicative RSL-like data (e.g. lake levels) on the continents far off the coasts. We present detailed sensitivity maps for four parameters important in GIA investigations (ice-load history, lithospheric thickness, background viscosity, lateral viscosity variations) for up to 9 dedicated times. Assuming an accuracy of 2 m of RSL data of all ages, we highlight areas around the world where, if the environmental conditions allowed its deposition and survival until today, RSL data of at least this accuracy may help to quantify the GIA modelling parameters above. The sensitivity to ice-load history variations is the dominating pattern covering in times of 14 ka BP and older almost the whole world. Lithospheric thickness variations are mainly only possible to be determined in certain high-latitude areas around the large former and current ice sheets. Background viscosity as well as lateral viscosity variations can be traced at most coast and shelf areas around the world, especially when dated to be older than 10 ka BP. The latter three are almost everywhere overlapped by the ice-load history pattern. In general we find that the more recent the data are, the smaller is the area of possible RSL locations which could provide enough information on the four GIA modelling parameters. But, we also note that when the accuracy of RSL data can be improved, e.g. from 2 m to 1 m, these areas become larger allowing better inference of background viscosity and lateral heterogeneity. Although the patterns depend on the chosen models and error limit, our results are indicative enough to outline areas where one should look for helpful RSL data of a certain time period.
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Allison, Lesley C., Matthew D. Palmer, and Ivan D. Haigh. "Projections of 21st century sea level rise for the coast of South Africa." Environmental Research Communications 4, no. 2 (February 1, 2022): 025001. http://dx.doi.org/10.1088/2515-7620/ac4a90.
Повний текст джерелаАнотація:
Abstract As a result of planetary heating, global mean sea level has increased since the end of the 19th century. Sea level rise is accelerating and will continue to rise over the 21st century and beyond. On top of the global mean signal there are large regional variations in the magnitude of sea level rise. At a local level, reliable projections of probable and possible future sea level change are vital for coastal management planning. In this work we present an observational analysis of recent sea level variations at locations around the coast of South Africa using tide gauge records and satellite altimetry data. In recent decades, sea level around South Africa has increased at a rate of around 3 mm year−1, consistent with estimates of global mean sea level rise over that time. We apply existing methods (that are rooted in the methods of the 5th Assessment Report of the Intergovernmental Panel on Climate Change, but with a number of methodological innovations) to produce sea level projections for eight locations around the coast of South Africa under low (RCP2.6) and high (RCP8.5) emissions scenarios. In the year 2100 locations around South Africa are projected to experience sea level rise (relative to 1986–2005) of approximately 0.5 m (0.25–0.8 m) following RCP2.6, or around 0.85 m (0.5–1.4 m) following RCP8.5. These increases are around 7%–14% larger than projections of global mean sea level, due to the local amplification of increases in several components of the sea level budget. The results from this work suggest that successful mitigation efforts to reduce greenhouse gas emissions would have a clear benefit in limiting 21st century sea level rise for South Africa.
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Jugier, Rémi, Michaël Ablain, Robin Fraudeau, Adrien Guerou, and Pierre Féménias. "On the uncertainty associated with detecting global and local mean sea level drifts on Sentinel-3A and Sentinel-3B altimetry missions." Ocean Science 18, no. 5 (September 1, 2022): 1263–74. http://dx.doi.org/10.5194/os-18-1263-2022.
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Abstract. An instrumental drift in the point target response (PTR) parameters has been detected on the Copernicus Sentinel-3A altimetry mission. It will affect the accuracy of sea level sensing, which could result in errors in sea level change estimates of a few tenths of a millimeter per year. In order to accurately evaluate this drift, a method for detecting global and regional mean sea level relative drifts between two altimetry missions is implemented. Associated uncertainties are also accurately calculated thanks to a detailed error budget analysis. A drift on both Sentinel-3A (S3A) and Sentinel-3B (S3B) global mean sea level (GMSL) is detected with values significantly higher than expected. For S3A, the relative GMSL drift detected is 1.0 mm yr−1 with Jason-3 and 1.3 mm yr−1 with SARAL/AltiKa. For S3B, the relative GMSL drift detected is −3.4 mm yr−1 with Jason-3 and −2.2 mm yr−1 with SARAL/AltiKa. The drift detected at global level does not show detectable regional variations above the uncertainty level of the proposed method. The investigations led by the altimeter experts can now explain the origin of this drift for S3A and S3B. The ability of the implemented method to detect a sea level drift with respect to the length of the common period is also analyzed. We find that the minimum detectable sea level drift over a 5-year period is 0.3 mm yr−1 at the global scale and 1.5 mm yr−1 at the 2400 km regional scale. However, these levels of uncertainty do not meet the sea level stability requirements for climate change studies.
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Merrifield, Mark A. "A Shift in Western Tropical Pacific Sea Level Trends during the 1990s." Journal of Climate 24, no. 15 (August 1, 2011): 4126–38. http://dx.doi.org/10.1175/2011jcli3932.1.
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Abstract Pacific Ocean sea surface height trends from satellite altimeter observations for 1993–2009 are examined in the context of longer tide gauge records and wind stress patterns. The dominant regional trends are high rates in the western tropical Pacific and minimal to negative rates in the eastern Pacific, particularly off North America. Interannual sea level variations associated with El Niño–Southern Oscillation events do not account for these trends. In the western tropical Pacific, tide gauge records indicate that the recent high rates represent a significant trend increase in the early 1990s relative to the preceding 40 years. This sea level trend shift in the western Pacific corresponds to an intensification of the easterly trade winds across the tropical Pacific. The wind change appears to be distinct from climate variations centered in the North Pacific, such as the Pacific decadal oscillation. In the eastern Pacific, tide gauge records exhibit higher-amplitude decadal fluctuations than in the western tropical Pacific, and the recent negative sea level trends are indistinguishable from these fluctuations. The shifts in trade wind strength and western Pacific sea level rate resemble changes in dominant global modes of outgoing longwave radiation and sea surface temperature. It is speculated that the western Pacific sea level response indicates a general strengthening of the atmospheric circulation over the tropical Pacific since the early 1990s that has developed in concert with recent warming trends.
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Ramkumar, Muthuvairavasamy. "Discrimination of tectonic dynamism, quiescence and third order relative sea level cycles of the Cauvery Basin, South India." Annales g?ologiques de la Peninsule balkanique, no. 76 (2015): 19–45. http://dx.doi.org/10.2298/gabp1576.
Повний текст джерелаАнотація:
Application of integrated stratigraphic modeling of sedimentary basins with the help of sequence and chemostratigraphic methods for improved understanding on the relative roles of depositional pattern and history of a Barremian-Danian stratigraphic record of the Cauvery Basin, India was attempted. Through enumeration of facies characteristics, tectonic structures and geochemical characteristics of the sedimentary rocks the use of geochemical signatures in distinguishing the relative roles of major factors has been evaluated. The results indicate that the geochemical signatures of the sedimentary rocks accurately record the prevalent geological processes and an ability to distinguish them through employing stratigraphic variations of compositional values and discrimination diagrams help in understanding the basinal history better. In addition, predomination of relative sea level fluctuations and active nature of tectonic movements during few time slices, which in turn was overwhelmed by sea level fluctuations are also inferred.
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Roseby, Zoë A., Katherine Southall, Fermin Alvarez-Agoues, Niamh Cahill, Gerard D. McCarthy, and Robin J. Edwards. "Two Centuries of Relative Sea-Level Rise in Dublin, Ireland, Reconstructed by Geological Tide Gauge." Open Quaternary 9 (August 22, 2023): 3. http://dx.doi.org/10.5334/oq.121.
Повний текст джерелаАнотація:
We demonstrate the utility and reproducibility of the saltmarsh foraminifera-based ‘geological tide gauge’ (GTG) approach by developing two independent records of relative sea-level (RSL) change for Dublin, Ireland. Our records, recovered from two different saltmarshes, indicate that RSL rose at a century-scale rate of 1.5 ± 0.9 mm yr–1 over the last 200 years. This compares favourably with the shorter, but more precise, mean sea level (MSL) record from the Dublin Port tide gauge, which indicates long-term (1953–2016 CE) rise at a rate of 1.1 ± 0.5 mm yr–1. When corrected for the influence of glacio-isostatic adjustment our saltmarsh-based reconstruction suggests sea levels in Dublin rose at a rate of 1.6 ± 0.9 mm yr–1 since the start of the 19th century, which is in excellent agreement with the regional value of MSL rise over the same period (1.5 ± 0.2 mm yr–1) calculated from a compilation of tide gauge records around Britain. Whilst our record has decadal-scale temporal resolution (1 sample every 8 years), we are currently unable to resolve multidecadal-scale variations in the rate of sea-level rise which are masked by the size of the vertical uncertainties (± 20 cm) associated with our reconstruction of palaeomarsh-surface elevation. We discuss the challenges of applying the GTG approach in the typically minerogenic saltmarshes of the NE Atlantic margin and outline potential solutions that would facilitate the production of Common Era RSL reconstructions in the region.
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Jara-Muñoz, Julius, and Daniel Melnick. "Unraveling Sea-Level Variations and Tectonic Uplift in Wave-Built Marine Terraces, Santa María Island, Chile." Quaternary Research 83, no. 1 (January 2015): 216–28. http://dx.doi.org/10.1016/j.yqres.2014.10.002.
Повний текст джерелаАнотація:
AbstractThe architecture of coastal sequences in tectonically-active regions results mostly from a combination of sea-level and land-level changes. The objective of this study is to unravel these signals by combining sequence stratigraphy and sedimentology of near-shore sedimentary sequences in wave-built terraces. We focus on Santa María Island at the south-central Chile margin, which hosts excellent exposures of coastal sediments from Marine Isotope Stage 3. A novel method based on statistical analysis of grain-size distributions coupled with facies descriptions provided a detailed account of transgressive–regressive cycles. Radiocarbon ages from paleosols constrain the chronology between > 53 and ~ 31 cal ka BP. Because the influence of glaciations can be neglected, we calculated relative sea-level curves by tying the onset of deposition on a bedrock abrasion platform to a global sea-level curve. The observed depositional cycles match those predicted for uplift rates between 1.2 and 1.8 m/ka. The studied sedimentary units represent depositional cycles that resulted in reoccupation events of an existing marine terrace. Our study demonstrates wave-built marine terrace deposits along clastic shorelines in temperate regions can be used to distinguish between tectonic uplift and climate-induced sea-level changes.
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Simon, K. M., R. E. M. Riva, and L. L. A. Vermeersen. "Constraint of glacial isostatic adjustment in the North Sea with geological relative sea level and GNSS vertical land motion data." Geophysical Journal International 227, no. 2 (July 7, 2021): 1168–80. http://dx.doi.org/10.1093/gji/ggab261.
Повний текст джерелаАнотація:
SUMMARY In this study, we focus on improved constraint of the glacial isostatic adjustment (GIA) signal at present-day, and its role as a contributor to present-day sea level budgets. The main study area extends from the coastal regions of northwestern Europe to northern Europe. Both Holocene relative sea level (RSL) data as well as vertical land motion (VLM) data are incorporated as constraints in a semi-empirical GIA model. 71 geological rates of GIA-driven RSL change are inferred from Holocene proxy data and 108 rates of vertical land motion from GNSS provide an additional measure of regional GIA deformation. Within the study area, the geological RSL data complement the spatial gaps of the VLM data and vice versa. Both data sets are inverted in a semi-empirical GIA model to yield updated estimates of regional present-day GIA deformations. A regional validation using tide gauges is presented for the North Sea, where the GIA signal may be complicated by lateral variations in Earth structure and existing predictions of regional and global GIA models show discrepancies. The model validation in the North Sea region suggests that geological data are needed to fit independent estimates of GIA-related RSL change inferred from tide gauge rates, indicating that geological rates from Holocene data do provide an important additional constraint for data-driven approaches to GIA estimation.
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Sola, Fernando, Juan C. Braga, and Gunnar Sælen. "Contradictory coeval vertical facies changes in upper Miocene heterozoan carbonate–terrigenous deposits (Sierra de Gádor, Almería, SE Spain)." Journal of Sedimentary Research 92, no. 3 (March 31, 2022): 257–74. http://dx.doi.org/10.2110/jsr.2022.010.
Повний текст джерелаАнотація:
ABSTRACT While spatial facies patterns can be observed in modern systems, only vertical facies successions can usually be examined in ancient deposits. Lateral facies relationships (depositional models) and relative sea-level changes throughout time are traditionally deduced from correlation of vertical facies successions along transects perpendicular to inferred paleo-shorelines. Establishing vertical facies successions and their corresponding time-equivalent proximal to distal facies patterns are, therefore, paramount in reconstructing ancient carbonate depositional systems and their response to sea-level change. In the present study of well-exposed panoramics of late Tortonian (8.1 Ma) mixed heterozoan carbonate and terrigenous deposits in La Chanata area in Sierra de Gádor, Almería, SE Spain, we show that frequent changes in facies width make it difficult to predict how variation in sea level impacts the facies distribution. The following facies are recognized: shoreline conglomerates directly overlie an erosion surface on the basement; terrigenous coralline-algal packstones extend basinwards from the conglomerates and are interpreted as shallow-water deposits stabilized by seagrass. There exist three types of facies consisting of relatively well-preserved, parautochthonous bioclasts, which occur generally seawards of the packstones: a) branching-coralline rudstones that formed from rhodolith (maërl) beds, both shorewards and basinwards from seagrass meadows where b) foliose-coralline rudstones to floatstones accumulated, and c) lenses of Heterostegina rudstones to floatstones changing laterally to any of the coralline algal facies. The factory facies of a–c show a patchy distribution with no definite arrangement in shoreline-parallel belts. The evolution of the depositional system is as follows: after filling paleovalleys in the erosion surface, deposition took place on a homoclinal ramp. The hybrid heterozoan carbonate–terrigenous deposits show a general retrogradation altered by one episode of proximal facies progradation. The width of facies across the ramp changes markedly in different episodes of relative sea-level rise: in several episodes of transgression, terrigenous coralline-algal packstones spread across the ramp locally overlying more distal facies, such as branching-coralline rudstones, thus generating regressive vertical patterns during relative sea-level rise. In other transgressive episodes packstones disappear, and the a–b factory facies pass laterally into conglomerate. The stratigraphic changes in facies width might be due to changes in general energy caused by climate variations or, alternatively, to the amount of relative sea-level rise. Large sea-level rise would result in relatively deep and calm conditions, thus favoring little fragmentation of large bioclasts during accumulation of the factory facies. Conversely, little change in accommodation would have resulted in higher-energy environments with concomitant increased physical erosion of the coralline-algae factories, thus resulting in mostly sand-size bioclasts in the packstones. In this environmental context, vertical change from distal to proximal facies can result from relative sea-level rise with increased mobilization and lateral expansion of proximal facies across the ramp. This outcome challenges the adequacy of using vertical lithofacies successions to reconstruct relative sea-level change in carbonate depositional systems.
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Steffen, H., P. Wu, and H. Wang. "Optimal locations of sea-level indicators in glacial isostatic adjustment investigations." Solid Earth 5, no. 1 (June 19, 2014): 511–21. http://dx.doi.org/10.5194/se-5-511-2014.
Повний текст джерелаАнотація:
Abstract. Fréchet (sensitivity) kernels are an important tool in glacial isostatic adjustment (GIA) investigations to understand lithospheric thickness, mantle viscosity and ice-load model variations. These parameters influence the interpretation of geologic, geophysical and geodetic data, which contribute to our understanding of global change. We discuss global sensitivities of relative sea-level (RSL) data of the last 18 000 years. This also includes indicative RSL-like data (e.g., lake levels) on the continents far off the coasts. We present detailed sensitivity maps for four parameters important in GIA investigations (ice-load history, lithospheric thickness, background viscosity, lateral viscosity variations) for up to nine dedicated times. Assuming an accuracy of 2 m of RSL data of all ages (based on analysis of currently available data), we highlight areas around the world where, if the environmental conditions allowed its deposition and survival until today, RSL data of at least this accuracy may help to quantify the GIA modeling parameters above. The sensitivity to ice-load history variations is the dominating pattern covering almost the whole world before about 13 ka (calendar years before 1950). The other three parameters show distinct patterns, but are almost everywhere overlapped by the ice-load history pattern. The more recent the data are, the smaller the area of possible RSL locations that could provide enough information to a parameter. Such an area is mainly limited to the area of former glaciation, but we also note that when the accuracy of RSL data can be improved, e.g., from 2 m to 1 m, these areas become larger, allowing better inference of background viscosity and lateral heterogeneity. Although the patterns depend on the chosen models and error limit, our results are indicative enough to outline areas where one should look for helpful RSL data of a certain time period. Our results also indicate that as long as the ice-load history is not sufficiently known, the inference of lateral heterogeneities in mantle viscosity or lithospheric thickness will be interfered by the uncertainty of the ice model.
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Bamber, J., and R. Riva. "The sea level fingerprint of recent ice mass fluxes." Cryosphere 4, no. 4 (December 21, 2010): 621–27. http://dx.doi.org/10.5194/tc-4-621-2010.
Повний текст джерелаАнотація:
Abstract. The sea level contribution from glacial sources has been accelerating during the first decade of the 21st Century (Meier et al., 2007; Velicogna, 2009). This contribution is not distributed uniformly across the world's oceans due to both oceanographic and gravitational effects. We compute the sea level signature for ice mass fluxes due to changes in the gravity field, Earth's rotation and related effects for the nine year period 2000–2008. Mass loss from Greenland results in a relative sea level (RSL) reduction for much of North Western Europe and Eastern Canada. RSL rise from this source is concentrated around South America. Losses in West Antarctica marginally compensate for this and produce maxima along the coastlines of North America, Australia and Oceania. The combined far-field pattern of wastage from all ice melt sources, is dominated by losses from the ice sheets and results in maxima at latitudes between 20° N and 40° S across the Pacific and Indian Oceans, affecting particularly vulnerable land masses in Oceania. The spatial pattern of RSL variations from ice mass losses used in this study is time-invariant and cumulative. Thus, sea level rise, based on the gravitational effects from the ice losses considered here, will be amplified for this sensitive region.
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Buonocore, Berardino, Yuri Cotroneo, Vincenzo Capozzi, Giuseppe Aulicino, Giovanni Zambardino, and Giorgio Budillon. "Sea-Level Variability in the Gulf of Naples and the “Acqua Alta” Episodes in Ischia from Tide-Gauge Observations in the Period 2002–2019." Water 12, no. 9 (September 2, 2020): 2466. http://dx.doi.org/10.3390/w12092466.
Повний текст джерелаАнотація:
This work presents an 18-year-long (2002–2019) tide-gauge dataset collected on the Island of Ischia (Gulf of Naples, Southern Tyrrhenian Sea) that can contribute to the analysis of the basic features of sea-level variability in this region. Analysis of tidal constituents shows that the Gulf of Naples is characterized by the absence of any amphidromic system. In this area, sea-level changes due to the astronomical component of the tide are generally limited to ±20 cm with respect to the mean sea level, but the impact of this variability is enhanced by global sea-level increase and the effect of regional atmospheric perturbations that might also triple sea-level variations. The effects of these events, whose frequency has increased in recent decades, has been dramatic in coastal areas where intense social and economic activity occurs, e.g., in Ischia. On interannual time scales, the results indicate that the relative sea-level rise in Ischia has a magnitude of 3.9 mm/year. Special attention is dedicated to the “acqua alta” episodes and to their linkage with long-term sea-level trends and atmospheric forcing.
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Beelen, Daan, Christopher A. L. Jackson, Stefano Patruno, David M. Hodgson, and João P. Trabucho Alexandre. "The effects of differential compaction on clinothem geometries and shelf-edge trajectories." Geology 47, no. 11 (September 6, 2019): 1011–14. http://dx.doi.org/10.1130/g46693.1.
Повний текст джерелаАнотація:
Abstract The geometry of basin-margin strata documents changes in water depth, slope steepness, and sedimentary facies distributions. Their stacking patterns are widely used to define shelf-edge trajectories, which reflect long-term variations in sediment supply and relative sea-level change. Here, we present a new method to reconstruct the geometries and trajectories of clinoform-bearing basin-margin successions. Our sequential decompaction technique explicitly accounts for downdip lithology variations, which are inherent to basin-margin stratigraphy. Our case studies show that preferential compaction of distal, fine-grained foresets and bottomsets results in a vertical extension of basin-margin strata and a basinward rotation of the original shelf-edge trajectory. We discuss the implications these effects have for sea-level reconstructions and for predicting the timing of sediment transfer to the basin floor.
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Kalaugher, P. G., and P. Grainger. "The influence of changes in sea level on coastal cliff instability in Devon." Geological Society, London, Engineering Geology Special Publications 7, no. 1 (1991): 361–67. http://dx.doi.org/10.1144/gsl.eng.1991.007.01.31.
Повний текст джерелаАнотація:
AbstractMajor variations in sea level have resulted from climatic changes during the Quaternary. In addition, beyond the maximum limit of glaciation, periglacial climates in southern Britain have produced Quaternary deposits which can affect the nature of coastal slopes and their response to marine erosion. Examples are given of cliffs in head (solifluction) deposits which overlie raised shore platforms in Devon. The present styles and distribution of coastal landslide hazards, recorded in recent surveys, are directly related to past Quaternary sea levels and climatic fluctuations. Future trends in relative sea level are a significant factor in the determination of the hazards in the longer term, as there could be changes in the level at which marine erosion is effective. Rankings of the hazards, which should in any case be updated routinely by repeated monitoring of the landslide activity, ought to reflect expected changes in sea level.
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Bamber, J., and R. Riva. "The sea level fingerprint of 21st century ice mass fluxes." Cryosphere Discussions 4, no. 3 (September 3, 2010): 1593–606. http://dx.doi.org/10.5194/tcd-4-1593-2010.
Повний текст джерелаАнотація:
Abstract. The sea level contribution from glacial sources has been accelerating during the 21st century (Meier et al., 2007; Velicogna, 2009). This contribution is not distributed uniformly across the world's oceans due to both oceanographic and gravitational effects. We compute the sea level signature of 21st century ice mass fluxes due to changes in the gravity field, Earth's rotation and related effects. Mass loss from Greenland results in a relative sea level (RSL) reduction for much of North Western Europe and Eastern Canada. RSL rise from this source is concentrated around South America. Losses in West Antarctica marginally compensate for this and produce maxima along the coastlines of North America, Australia and Oceania. The combined far-field pattern of wastage from all ice melt sources, is dominated by losses from the ice sheets and results in maxima at latitudes between 20° N and 40° S across the Pacific and Indian Oceans, affecting particularly vulnerable land masses in Oceania. The spatial pattern of RSL variations due to the observed ice mass loss is temporally invariant. Thus, sea level rise, based on the land ice losses considered here, will be amplified for this sensitive region.
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Kuhn, Lidia A., Karin A. F. Zonneveld, Paulo A. Souza, and Rodrigo R. Cancelli. "Late Quaternary palaeoenvironmental evolution and sea level oscillation of Santa Catarina Island (southern Brazil)." Biogeosciences 20, no. 10 (May 23, 2023): 1843–61. http://dx.doi.org/10.5194/bg-20-1843-2023.
Повний текст джерелаАнотація:
Abstract. Sea level oscillation during the Quaternary played a major role in the geomorphology and vegetation dynamics of coastal areas in southern Brazil, encompassing ecosystems that often have a unique biodiversity. Understanding the natural evolution of these areas is essential for decision making regarding land use regulations towards sustainable development, as well as to preserve the uniqueness of the coastal ecosystems. The southern Brazil coastal plain is formed by marine, transitional and continental Quaternary deposits controlled by past variations of the sea level. These variations shaped the coastal landscape and influenced the development of different Atlantic rainforest formations, such as mangroves and restingas. In particular, the restinga formation corresponds to a specific ecosystem that covers sandy soils of marine and fluvial–marine origin formed during the Quaternary on the Brazilian coastal plain. In this contribution, we present high-resolution palynological and stable isotope data from a Holocene core retrieved from the coastal plain of Santa Catarina Island (southern Brazil). We were able to identify four different environmental zones for the last 6520 yr BP. The first zone (6520–2920 cal yr BP) is characterized by a lagoon with large marine-water influence. Notably, the observed dinoflagellate cyst association suggests that marine waters entering the region had their origin in the relatively warm and saline Brazil Current waters. During the second zone (2920–1520 cal yr BP), marine-water contribution to the lagoon decreased until it became disconnected from the sea. The third zone (1520–550 cal yr BP) was marked by the decrease of the water level until it dried out and led to the colonization of herbaceous vegetation over the palaeo-lagoon. The last zone (550 cal yr BP–recent) is characterized by the consolidation of the coastal-plain Atlantic rainforest (restinga vegetation). Our results form an example of the strong sensitivity of southern Brazilian ecosystem change caused by relative sea level variations. As such, this study might contribute to the debate about the potential effects of current climate change induced by global sea level variations.