scholarly journals MISELA: 1-minute sea-level analysis global dataset

2021 ◽  
Author(s):  
Petra Zemunik ◽  
Jadranka Šepić ◽  
Havu Pellikka ◽  
Leon Ćatipović ◽  
Ivica Vilibić
Keyword(s):  
Sea Level ◽  
Tide Gauge ◽  
Spatial Scales ◽  
Data Quality Control ◽  
Coastal Waves ◽  
Tidal Basins ◽  
Sea Level Oscillations ◽  
Control Procedures ◽  
Level Analysis ◽  
Local Research

Abstract. Sea-level observations provide information on a variety of processes occurring over different temporal and spatial scales that may contribute to coastal flooding and hazards. However, global research of sea-level extremes is restricted to hourly datasets, which prevent quantification and analyses of processes occurring at timescales between a few minutes and a few hours. These shorter period processes, like seiches, meteotsunamis, infragravity and coastal waves, may even dominate in low-tidal basins. Therefore, a new global 1-minute sea-level dataset – MISELA (Minute Sea-Level Analysis) – has been developed, encompassing quality-checked records of nonseismic sea-level oscillations at tsunami timescales (T < 2 h) obtained from 331 tide-gauge sites (https://doi.org/10.14284/456, Zemunik et al., 2021b). This paper describes data quality-control procedures applied to the MISELA dataset, world and regional coverage of tide-gauge sites and lengths of time-series. The dataset is appropriate for global, regional or local research of atmospherically-induced high-frequency sea-level oscillations, which should be included in the overall sea-level extremes assessments.

scholarly journals Minute Sea-Level Analysis (MISELA): a high-frequency sea-level analysis global dataset

2021 ◽  
Vol 13 (8) ◽  
pp. 4121-4132
Author(s):  
Petra Zemunik ◽  
Jadranka Šepić ◽  
Havu Pellikka ◽  
Leon Ćatipović ◽  
Ivica Vilibić
Keyword(s):  
Sea Level ◽  
High Frequency ◽  
Tide Gauge ◽  
Spatial Scales ◽  
Data Quality Control ◽  
Coastal Waves ◽  
Tidal Basins ◽  
Sea Level Oscillations ◽  
Control Procedures ◽  
Level Analysis

Abstract. Sea-level observations provide information on a variety of processes occurring over different temporal and spatial scales that may contribute to coastal flooding and hazards. However, global research on sea-level extremes is restricted to hourly datasets, which prevent the quantification and analyses of processes occurring at timescales between a few minutes and a few hours. These shorter-period processes, like seiches, meteotsunamis, infragravity and coastal waves, may even dominate in low tidal basins. Therefore, a new global 1 min sea-level dataset – MISELA (Minute Sea-Level Analysis) – has been developed, encompassing quality-checked records of nonseismic sea-level oscillations at tsunami timescales (T<2 h) obtained from 331 tide-gauge sites (https://doi.org/10.14284/456, Zemunik et al., 2021b). This paper describes data quality control procedures applied to the MISELA dataset, world and regional coverage of tide-gauge sites, and lengths of time series. The dataset is appropriate for global, regional or local research of atmospherically induced high-frequency sea-level oscillations, which should be included in the overall sea-level extremes assessments.

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

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

&lt;p&gt;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 &gt; 2 h) sea-level oscillations to the phenomena has been well researched, the contribution of the shorter period (T &lt;&amp;#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.&amp;#160;&lt;/p&gt;&lt;p&gt;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 &lt; 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.&amp;#160;&amp;#160;&lt;/p&gt;&lt;p&gt;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.&amp;#160;&lt;/p&gt;

How Salty Is the Global Ocean: Weighting It All or Tasting It a Sip at a Time?

2020 ◽  
Author(s):  
Rui Ponte ◽  
Qiang Sun ◽  
Chao Liu ◽  
Xinfeng Liang
Keyword(s):  
Sea Ice ◽  
Sea Level ◽  
Hydrological Cycle ◽  
Global Ocean ◽  
Data Quality Control ◽  
Argo Data ◽  
Terrestrial Water ◽  
Control Procedures ◽  
Global Mean Sea Level

&lt;div class=&quot;page&quot; title=&quot;Page 1&quot;&gt; &lt;div class=&quot;section&quot;&gt; &lt;div class=&quot;layoutArea&quot;&gt; &lt;div class=&quot;column&quot;&gt; &lt;p&gt;Global ocean mean salinity &lt;em&gt;S &lt;/em&gt;is a key indicator of the Earth's hydrological cycle and the exchanges of freshwater between the terrestrial water and ice reservoirs and the ocean. We explore two different ways of determining how salty the ocean is: (1) use in situ salinity measurements to taste the ocean a sip at a time and obtain a sample average; (2) use space gravimetry to weigh the whole ocean including sea-ice, and then separate sea-ice effects to infer changes in liquid freshwater content and thus &lt;em&gt;S&lt;/em&gt;. Focusing on the 2005-2019 period, we assess monthly series of &lt;em&gt;S &lt;/em&gt;derived from five different in situ gridded products, based mostly but not exclusively on Argo data, versus a series obtained from GRACE and GRACE Follow-On data and available sea ice mass estimates.&lt;/p&gt; &lt;p&gt;There is little consistency in &lt;em&gt;S &lt;/em&gt;series from the two methods for all time scales examined (seasonal, interannual, long-term trend). In situ series show larger variability, particularly at the longest scales, and are somewhat incoherent with the GRACE-derived series. In addition, there are wide spread differences among all the in situ &lt;em&gt;S &lt;/em&gt;series, which denote their considerable sensitivity to choice of data, quality control procedures, and mapping methods. Results also suggest that in situ &lt;em&gt;S &lt;/em&gt;values are prone to systematic biases, with most series showing increases after around 2014 that are equivalent to a drop in barystatic sea level of tens of centimeters! Estimates derived from GRACE are much smaller in magnitude and consistent with contributions of freshwater to the global mean sea level budgets, and they are thus more reliable than in situ-based &lt;em&gt;S &lt;/em&gt;estimates. The existence of GRACE-derived estimates can serve as a consistency check on in situ measurements, revealing potential unknown biases and providing a way to cross-calibrate the latter data.&lt;/p&gt; &lt;/div&gt; &lt;/div&gt; &lt;/div&gt; &lt;/div&gt;

scholarly journals Neapolitan volcanic area Tide Gauge Network (Southern Italy): Ground Displacements and Sea-Level Oscillations

2021 ◽  
Vol 52 ◽  
pp. 105-118
Author(s):  
Umberto Tammaro ◽  
Francesco Obrizzo ◽  
Umberto Riccardi ◽  
Adriano La Rocca ◽  
Salvatore Pinto ◽  
...  
Keyword(s):  
Sea Level ◽  
Southern Italy ◽  
Tide Gauge ◽  
Low Frequency ◽  
Campi Flegrei ◽  
Volcanic Area ◽  
Tide Gauge Records ◽  
Gulf Of Naples ◽  
Sea Level Oscillations ◽  
Resolution Model

Abstract. In this study, we investigate the oscillations of relative sea level through the analysis of tide gauge records about 10-year long collected in the Gulfs of Pozzuoli and Napoli (Southern Italy). The main goal of this study is to provide a suitable resolution model of the sea tides including low frequency (seiches), tidal bands and non-linear tides. The spectral analyses of the tide gauge records lead us to identify a number of seiche periods some of them already known from the literature and some other unknown. Furthermore, we target a non-conventional purpose of the tidal analysis, namely extracting from the tide gauge records the volcano-tectonic signal (vertical ground displacement) in the resurgent Campi Flegrei caldera. We suggest a method to filter out the volcano-tectonic signal (bradyseism) from the tide gauge records by deconvolving it from two records, one collected in the active volcanic area (Pozzuoli) and the other one collected in a tectonically stable station (Napoli), located beyond the caldera rim. Finally, we retrieve the relative mean sea level change in the Gulf of Naples and compare it with the trend found in five tide gauges spread along the Italian coast.

scholarly journals Sea level analysis using tide gauge observations at the northern delta coast, Egypt

2021 ◽  
Vol 10 (1) ◽  
pp. 361-371
Author(s):  
Ali M. Radwan ◽  
Mohamed Magdy ◽  
Mostafa Rabah ◽  
Ahmed Saber ◽  
Ahmed Zaki
Keyword(s):  
Sea Level ◽  
Tide Gauge ◽  
Level Analysis

scholarly journals The Zone of Influence: Matching sea level variability from coastal altimetry and tide gauges for vertical land motion estimation

2020 ◽  
Author(s):  
Julius Oelsmann ◽  
Marcello Passaro ◽  
Denise Dettmering ◽  
Christian Schwatke ◽  
Laura Sanchez ◽  
...  
Keyword(s):  
Sea Level ◽  
Tide Gauge ◽  
Spatial Scales ◽  
Tide Gauges ◽  
Relative Sea Level ◽  
Sea Level Variability ◽  
Vertical Land Motion ◽  
Spatial Coverage ◽  
Coupling Procedure ◽  
Zone Of Influence

Abstract. Vertical land motion (VLM) at the coast is a substantial contributor to relative sea level change. In this work, we present a refined method for its determination, which is based on the combination of absolute satellite alimetry (SAT) sea level measurements and relative sea level changes recorded by tide gauges (TG). These measurements complement VLM estimates based on GNSS (Global Navigation Satellite System) by increasing their spatial coverage. Trend estimates from SAT and TG combination are particularly sensitive to the quality and resolution of applied altimetry data as well as to the coupling procedure of altimetry and tide gauges. Hence, a multi-mission, dedicated coastal along-track altimetry dataset is coupled with highfrequent tide gauge measurements at 58 stations. To improve the coupling-procedure, a so-called `Zone of Influence’ is defined to identify coherent zones of sea level variability on the basis of relative levels of comparability between tide gauge and altimetry observations. Selecting 20 % of the most representative absolute sea level observations in a 300 km radius around the tide gauges results in the best VLM-estimates in terms of accuracies and uncertainties. At this threshold, VLM_SAT-TG estimates have median formal uncertainties of 0.59 mm/year. Validation against GNSS VLM estimates yields a root-mean-square (RMS_VLM) of VLM_SAT-TG and VLM_GNSS differences of 1.28 mm/year, demonstrating the level of accuracy of our approach. Compared to a reference 250 km radius selection of sea level anomalies, the 300 km Zone of Influence improves trend accuracies by 12 % and uncertainties by 28 %. With progressing record lengths, the spatial scales of coastal sea level trend coherency increase. Therefore the relevance of the ZOI for improving VLM_SAT-TG accuracies decreases. Further individual Zone of Influence adaptations offer the prospect of bringing the accuracy of the estimates below 1 mm/year.

Recent relative sea-level trends: an attempt to quantify the forcing factors

2006 ◽  
Vol 364 (1841) ◽  
pp. 821-844 ◽  
Author(s):  
Hans-Peter Plag
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Tide Gauge ◽  
Spatial Scales ◽  
Ice Sheets ◽  
Global Ocean ◽  
Tide Gauges ◽  
Global Average ◽  
Global Sea Level ◽  
The Antarctic

Local sea-level is affected by a number of forcing factors, which all contribute to the trends observed by tide gauges. Here we use the fingerprints of main factors contributing to secular sea-level trends to construct an initial empirical model that explains best the trends in sea-level as recorded by the large number of coastal tide gauges over the last 50 years. The forcing factors considered include steric changes derived from observations, post-glacial rebound as predicted by geophysical models and mass changes in the Greenland and Antarctic ice sheets as predicted by the static sea-level equation. The approximation of the observed spatial pattern of sea-level trends through a model based on the spatial fingerprints of the main forcing factors fully utilizes the information contents of the available observations and models and allows the interpolation of the sea-level trends between the tide gauges. As a result, we obtain the global picture of sea-level trends due to the forcing factors accounted for in the analysis. Moreover, we derive constraints on the mass changes of the large ice sheets. The empirical models explain about 15% of the variance of the sea-level trends. Nevertheless, the models are correlated with the observations on the level of 0.38±0.07, indicating that most of the unexplained variance is due to contributions with small spatial scales. Averaged over the last five decades, the results indicate that the Antarctic and Greenland ice sheets have been melting with an equivalent contribution to global sea-level rise of 0.39±0.11 and 0.10±0.05 mm yr −1 , respectively. The steric signal derived from observations is clearly identified in the sea-level trends and is found to be at a minimum of 0.2 mm yr −1 , with the most likely value being close to 0.35 mm yr −1 . The global tide gauge network, which covers only a small fraction of the ocean surface, appears to sense an average sea-level rise larger than the global average. Extrapolating the regression models to the global ocean and taking into account the uncertainties in the extrapolation results in a most likely global average of the order of 1.05±0.75 mm yr −1 .

scholarly journals Coastal sea level response to the tropical cyclonic forcing in the northern Indian Ocean

Ocean Science ◽  
2015 ◽  
Vol 11 (1) ◽  
pp. 159-173 ◽  
Author(s):  
P. Mehra ◽  
M. Soumya ◽  
P. Vethamony ◽  
K. Vijaykumar ◽  
T. M. Balakrishnan Nair ◽  
...  
Keyword(s):  
Sea Level ◽  
West Coast ◽  
Arabian Sea ◽  
East Coast ◽  
Tide Gauge ◽  
Meteorological Data ◽  
Linear Regression Analysis ◽  
The West ◽  
Cyclonic Storm ◽  
Sea Level Oscillations

Abstract. The study examines the observed storm-generated sea level variation due to deep depression (event 1: E1) in the Arabian Sea from 26 November to 1 December 2011 and a cyclonic storm "THANE" (event 2: E2) over the Bay of Bengal during 25–31 December 2011. The sea level and surface meteorological measurements collected during these extreme events exhibit strong synoptic disturbances leading to storm surges of up to 43 cm on the west coast and 29 cm on the east coast of India due to E1 and E2. E1 generated sea level oscillations at the measuring stations on the west coast (Ratnagiri, Verem and Karwar) and east coast (Mandapam and Tuticorin) of India with significant energy bands centred at periods of 92, 43 and 23 min. The storm surge is a well-defined peak with a half-amplitude width of 20, 28 and 26 h at Ratnagiri, Verem and Karwar, respectively. However, on the east coast, the sea level oscillations during Thane were similar to those during calm period except for more energy in bands centred at periods of ~ 100, 42 and 24 min at Gopalpur, Gangavaram and Kakinada, respectively. The residual sea levels from tide gauge stations in Arabian Sea have been identified as Kelvin-type surges propagating northwards at a speed of ~ 6.5 m s−1 with a surge peak of almost constant amplitude. Multi-linear regression analysis shows that the local surface meteorological data (daily mean wind and atmospheric pressure) is able to account for ~ 57 and ~ 69% of daily mean sea level variability along the east and west coasts of India. The remaining part of the variability observed in the sea level may be attributed to local coastal currents and remote forcing.

scholarly journals Statistical properties of coastal long waves analysed through sea-level time-gradient functions: exemplary analysis of the Siracusa, Italy, tide-gauge data

2015 ◽  
Vol 3 (9) ◽  
pp. 5247-5286
Author(s):  
L. Bressan ◽  
S. Tinti
Keyword(s):  
Sea Level ◽  
Control Function ◽  
Tide Gauge ◽  
Distribution Functions ◽  
Storm Waves ◽  
Sea Level Oscillations ◽  
Wave Range ◽  
Waves And Tides ◽  
T Distribution ◽  
Fft Analysis

Abstract. This study presents a new method to analyse the properties of the sea-level signal recorded by coastal tide gauges in the long wave range that is in a window between wind/storm waves and tides and is typical of several phenomena like local seiches, coastal shelf resonances and tsunamis. The method consists of computing four specific functions based on the time gradient (slope) of the recorded sea level oscillations, namely the instantaneous slope IS, and three more functions based on IS, that are the sea level SL, the background slope BS and the control function CF. These functions are examined through a traditional spectral FFT analysis and also through a statistical analysis showing that they can be characterised by probability distribution functions PDFs such as the Student's t distribution (IS and SL) and the Beta distribution (CF). As an example, the method has been applied to data from the tide-gauge station of Siracusa, Italy.

scholarly journals Statistical properties of coastal long waves analysed through sea-level time-gradient functions: exemplary analysis of the Siracusa, Italy, tide-gauge data

2016 ◽  
Vol 16 (1) ◽  
pp. 223-237 ◽  
Author(s):  
L. Bressan ◽  
S. Tinti
Keyword(s):  
Sea Level ◽  
Control Function ◽  
Tide Gauge ◽  
Distribution Functions ◽  
Storm Waves ◽  
Sea Level Oscillations ◽  
Wave Range ◽  
Waves And Tides ◽  
T Distribution ◽  
Fft Analysis

Abstract. This study presents a new method to analyse the properties of the sea-level signal recorded by coastal tide gauges in the long wave range that is in a window between wind/storm waves and tides and is typical of several phenomena like local seiches, coastal shelf resonances and tsunamis. The method consists of computing four specific functions based on the time gradient (slope) of the recorded sea level oscillations, namely the instantaneous slope (IS) as well as three more functions based on IS, namely the reconstructed sea level (RSL), the background slope (BS) and the control function (CF). These functions are examined through a traditional spectral fast Fourier transform (FFT) analysis and also through a statistical analysis, showing that they can be characterised by probability distribution functions PDFs such as the Student's t distribution (IS and RSL) and the beta distribution (CF). As an example, the method has been applied to data from the tide-gauge station of Siracusa, Italy.

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