Australia: An Unstable Platform for Tide-Gauge Measurements of Changing Sea Levels: A Discussion

Researchers demonstrate the value of combining GPS and satellite data on vertical motion of the Earth's surface with tide gauge measurements to track rising sea levels.

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Assessment of static flood modeling techniques: application to contrasting marshes flooded during Xynthia (western France)

Natural Hazards and Earth System Science ◽

10.5194/nhess-13-1595-2013 ◽

2013 ◽

Vol 13 (6) ◽

pp. 1595-1612 ◽

Cited By ~ 50

Author(s):

J. F. Breilh ◽

E. Chaumillon ◽

X. Bertin ◽

M. Gravelle

Keyword(s):

Tide Gauge ◽

Western Coast ◽

Flood Modeling ◽

Sea Levels ◽

Modeling Methods ◽

Dynamic Methods ◽

Modeling Techniques ◽

Storm Surge Modeling ◽

Tide Gauge Measurements ◽

Flooded Areas

Abstract. This study aims to assess the performance of raster-based flood modeling methods on a wide diversity of coastal marshes. These methods are applied to the flooding associated with the storm Xynthia, which severely hit the western coast of France in February 2010. Static and semi-dynamic methods are assessed using a combination of LiDAR data, post-storm delineation of flooded areas and sea levels originating from both tide gauge measurements and storm surge modeling. Static methods are applied to 27 marshes showing a wide geomorphological diversity. It appears that these methods are suitable for marshes with a small distance between the coastline and the landward boundary of the marsh, which causes these marshes to flood rapidly. On the contrary, these methods overpredict flooded areas for large marshes where the distance between the coastline and the landward boundary of the marsh is large, because the flooding cannot be considered as instantaneous. In this case, semi-dynamic methods based on surge overflowing volume calculations can improve the flooding prediction significantly. This study suggests that static and semi-dynamic flood modeling methods can be attractive and quickly deployed to rapidly produce predictive flood maps of vulnerable areas under certain conditions, particularly for small distances between the coastline and the landward boundary of the low-lying coastal area.

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Antarctic Peninsula sea levels: a real-time system for monitoring Drake Passage transport

Antarctic Science ◽

10.1017/s0954102006000472 ◽

2006 ◽

Vol 18 (3) ◽

pp. 429-436 ◽

Cited By ~ 10

Author(s):

P.L. Woodworth ◽

C.W. Hughes ◽

D.L. Blackman ◽

V.N. Stepanov ◽

S.J. Holgate ◽

...

Keyword(s):

Southern Ocean ◽

Real Time ◽

Antarctic Peninsula ◽

Tide Gauge ◽

Drake Passage ◽

Southern Annular Mode ◽

Time System ◽

International Polar Year ◽

Real Time System ◽

Sea Levels

Sub-surface pressure (SSP) data from tide gauges at three bases on the Pacific coast of the Antarctic Peninsula, together with SSP information from a bottom pressure recorder deployed on the south side of the Drake Passage, have been used to study the relationships between SSP, Drake Passage transport, and the strength of Southern Ocean zonal winds as represented by the Southern Annular Mode. High correlations were obtained between all parameters, confirming results obtained previously with independent data sets, and demonstrating the value of information from the permanent Rothera base, the southern-most site considered. These are important findings with regard to the design, installation and maintenance of observation networks in Antarctica. In particular, they provide the necessary justification for Antarctic Peninsula tide gauge infrastructure investment in the lead up to International Polar Year. Data delivery from Rothera and Vernadsky is currently being improved and should soon enable the first near real-time system for monitoring Drake Passage transport variability on intraseasonal timescales, an essential component of a Southern Ocean Observing System.

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

10.5194/egusphere-egu21-4602 ◽

2021 ◽

Author(s):

Krešimir Ruić ◽

Jadranka Šepić ◽

Maja Karlović ◽

Iva Međugorac

Keyword(s):

Time Series ◽

Sea Level ◽

High Frequency ◽

Adriatic Sea ◽

Tide Gauge ◽

Data Series ◽

Sea Levels ◽

Short Period ◽

Extreme Sea Levels ◽

Sea Level Oscillations

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

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Synthetically generated low-pressure systems to support studies of sea level extremes

10.5194/ems2021-132 ◽

2021 ◽

Author(s):

Mika Rantanen ◽

Jani Särkkä ◽

Jani Räihä ◽

Matti Kämäräinen ◽

Kirsti Jylhä

Keyword(s):

Sea Level ◽

Power Plants ◽

Tide Gauge ◽

Gaussian Function ◽

Low Pressure ◽

Tide Gauge Records ◽

Pressure System ◽

Sea Levels ◽

Input Parameters ◽

Low Pressure Systems

Extremely high sea levels on the Finnish coast are typically caused by close passages of extratropical cyclones (ETCs), which raise the sea level with their associated extreme winds and lower air pressure. For coastal infrastructure, such as nuclear power plants, it is crucial to study physically possible sea level heights associated with ETCs. Such sea levels are not straightforward to determine from observational datasets only, because tide gauge records&#160; cover about 100 years and do not necessarily capture the most extreme cases having return periods longer than 100 years.In this study, a method for generating an ensemble of synthetic low-pressure systems is being developed to investigate the extreme sea level heights on the Finnish coast of Baltic sea. As input parameters for the method, the point of origin, velocity of the center of the cyclone and depth of the pressure anomaly need to be given. Based on the input parameters, the method forms an idealized low-pressure system using a two-dimensional Gaussian function. In order to find extreme, but still reasonable values for the input parameters, cyclone tracks from ERA5 reanalysis data will be analysed.The ensemble of synthetic low pressure systems (i.e. the wind and pressure data) is used as an input to a numerical sea level model. As a result, we have an ensemble of simulated sea levels, from which we can determine the properties of the ETCs that induce the highest sea levels on a given location on the coast. The preliminary simulation results show that this method works well, forming a basis for studies on extreme sea levels.&#160;&#160;

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The northern and the eastern Adriatic Sea floods: connecting the extreme sea-levels to cyclone pathways

10.5194/egusphere-egu21-8201 ◽

2021 ◽

Author(s):

Tihana Dević ◽

Jadranka Šepić ◽

Darko Koračin

Keyword(s):

Sea Level ◽

Tide Gauge ◽

Middle Eastern ◽

Origin Time ◽

Northern Adriatic ◽

Sea Levels ◽

North West ◽

Mediterranean Cyclones ◽

Extreme Sea Levels ◽

The Moment

An objective method for tracking pathways of cyclone centres over Europe was developed and applied to the ERA-Interim reanalysis atmospheric data (1979-2014). The method was used to determine trajectories of those Mediterranean cyclones which generated extreme sea levels along the northern and the eastern Adriatic coast during the period from 1979 to 2014. Extreme events were defined as periods during which sea level was above 99.95 percentile value of time series of hourly sea-level data measured at the Venice (northern Adriatic), Split (middle eastern Adriatic) and Dubrovnik (south-eastern Adriatic) tide-gauge stations. The cyclone pathways were tracked backwards from the moment closest to the moment of maximum sea level up to the cyclone origin time, or at most, up to 72 hours prior the occurrence of the sea-level maximum.Our results point out that extreme sea levels in Venice normally appear during synoptic situations in which a cyclone centre is located to the south-west and north-west of Venice, i.e., when it can be found over the Gulf of Genoa, or the Alps. On the contrary, extreme sea levels in Dubrovnik are usually associates with cyclone centres above the middle Adriatic, whereas floods in Split seem to appear during both above-described types of situations.Occurrence times and intensity of cyclones and extreme sea-levels was further associated with the NAO index. It has been shown that the deepest cyclones and corresponding extreme floods tend to occur during the negative NAO phase. &#160;&#160;

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Atmospheric circulation changes and their impact on extreme sea levels around Australia

Natural Hazards and Earth System Science ◽

10.5194/nhess-19-1067-2019 ◽

2019 ◽

Vol 19 (5) ◽

pp. 1067-1086 ◽

Cited By ~ 4

Author(s):

Frank Colberg ◽

Kathleen L. McInnes ◽

Julian O'Grady ◽

Ron Hoeke

Keyword(s):

Sea Level ◽

Large Scale ◽

Climate Models ◽

Tide Gauge ◽

Austral Summer ◽

Sea Level Changes ◽

Sea Level Variability ◽

Sea Levels ◽

Extreme Sea Levels ◽

Coastal Sea

Abstract. Projections of sea level rise (SLR) will lead to increasing coastal impacts during extreme sea level events globally; however, there is significant uncertainty around short-term coastal sea level variability and the attendant frequency and severity of extreme sea level events. In this study, we investigate drivers of coastal sea level variability (including extremes) around Australia by means of historical conditions as well as future changes under a high greenhouse gas emissions scenario (RCP 8.5). To do this, a multi-decade hindcast simulation is validated against tide gauge data. The role of tide–surge interaction is assessed and found to have negligible effects on storm surge characteristic heights over most of the coastline. For future projections, 20-year-long simulations are carried out over the time periods 1981–1999 and 2081–2099 using atmospheric forcing from four CMIP5 climate models. Changes in extreme sea levels are apparent, but there are large inter-model differences. On the southern mainland coast all models simulated a southward movement of the subtropical ridge which led to a small reduction in sea level extremes in the hydrodynamic simulations. Sea level changes over the Gulf of Carpentaria in the north are largest and positive during austral summer in two out of the four models. In these models, changes to the northwest monsoon appear to be the cause of the sea level response. These simulations highlight a sensitivity of this semi-enclosed gulf to changes in large-scale dynamics in this region and indicate that further assessment of the potential changes to the northwest monsoon in a larger multi-model ensemble should be investigated, together with the northwest monsoon's effect on extreme sea levels.

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Very-Long-Baseline Interferometry Applied to Geophysics

Symposium - International Astronomical Union ◽

10.1017/s0074180900173115 ◽

1993 ◽

Vol 156 ◽

pp. 133-144

Author(s):

W. E. Carter ◽

D. S. Robertson

Keyword(s):

Very Long Baseline Interferometry ◽

Tide Gauge ◽

Global Changes ◽

Long Baseline ◽

Tidal Forces ◽

The Earth ◽

Tide Gauge Measurements ◽

Rotation Of The Earth ◽

Global Reference Frame

Very-long-baseline Interferometry (VLBI) has opened for study a broad new spectrum of geophysical phenomena including: direct observation of the tectonic motions and deformations of the Earth's crustal plates, observations of unprecedented detail of the variations in the rotation of the Earth, and direct measurement of the elastic deformations of the Earth in response to tidal forces. These new measurements have placed significant constraints on models of the interior structure of the Earth; for example, measurements of the variations in the Earth's nutation have been shown to be particularly sensitive to the shape of the core-mantle boundary. The VLBI measurements will allow us to construct a global reference frame accurate at the centimeter level. Such a frame will be essential to studying long-term global changes, especially those changes related to sea-level variations as recorded by tide gauge measurements.

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