scholarly journals Statistical trend analysis and extreme distribution of significant wave height from 1958 to 1999 – an application to the Italian Seas

Ocean Science ◽  
2010 ◽  
Vol 6 (2) ◽  
pp. 525-538 ◽  
Author(s):  
G. Martucci ◽  
S. Carniel ◽  
J. Chiggiato ◽  
M. Sclavo ◽  
P. Lionello ◽  
...  
Keyword(s):  
Extreme Values ◽  
Wave Model ◽  
Northern Adriatic Sea ◽  
Sea State ◽  
Northern Adriatic ◽  
Significant Wave ◽  
Peak Over Threshold ◽  
Wave Heights ◽  
Italian Coasts ◽  
A Site

Abstract. The study is a statistical analysis of sea states timeseries derived using the wave model WAM forced by the ERA-40 dataset in selected areas near the Italian coasts. For the period 1 January 1958 to 31 December 1999 the analysis yields: (i) the existence of a negative trend in the annual- and winter-averaged sea state heights; (ii) the existence of a turning-point in late 80's in the annual-averaged trend of sea state heights at a site in the Northern Adriatic Sea; (iii) the overall absence of a significant trend in the annual-averaged mean durations of sea states over thresholds; (iv) the assessment of the extreme values on a time-scale of thousand years. The analysis uses two methods to obtain samples of extremes from the independent sea states: the r-largest annual maxima and the peak-over-threshold. The two methods show statistical differences in retrieving the return values and more generally in describing the significant wave field. The r-largest annual maxima method provides more reliable predictions of the extreme values especially for small return periods (<100 years). Finally, the study statistically proves the existence of decadal negative trends in the significant wave heights and by this it conveys useful information on the wave climatology of the Italian seas during the second half of the 20th century.

scholarly journals Statistical trend analysis and extreme distribution of significant wave height from 1958 to 1999 – an application to the Italian Seas

2009 ◽  
Vol 6 (3) ◽  
pp. 2005-2036 ◽  
Author(s):  
G. Martucci ◽  
S. Carniel ◽  
J. Chiggiato ◽  
M. Sclavo ◽  
P. Lionello ◽  
...  
Keyword(s):  
Extreme Values ◽  
Wave Model ◽  
Northern Adriatic Sea ◽  
Sea State ◽  
Northern Adriatic ◽  
Significant Wave ◽  
Peak Over Threshold ◽  
Wave Heights ◽  
Italian Coasts ◽  
A Site

Abstract. The study is a statistical analysis of sea states timeseries derived using the wave model WAM forced by the ERA-40 dataset in selected areas near the Italian coasts. For the period 1 January 1958 to 31 December 1999 the analysis yields: (i) the existence of a negative trend in the annual- and winter-averaged sea state heights; (ii) the existence of a turning-point in late 70's in the annual-averaged trend of sea state heights at a site in the Northern Adriatic Sea; (iii) the overall absence of a significant trend in the annual-averaged mean durations of sea states over thresholds; (iv) the assessment of the extreme values on a time-scale of thousand years. The analysis uses two methods to obtain samples of extremes from the independent sea states: the r-largest annual maxima and the peak-over-threshold. The two methods show statistical differences in retrieving the return values and more generally in describing the significant wave field. The study shows the existence of decadal negative trends in the significant wave heights and by this it conveys useful information on the wave climatology of the Italian seas during the second half of the 20th century.

scholarly journals Accuracy of altimeter data in inner and coastal seas

2018 ◽  
Author(s):  
Luigi Cavaleri ◽  
Luciana Bertotti ◽  
Paolo Pezzutto
Keyword(s):  
Wind Speed ◽  
High Frequency ◽  
Adriatic Sea ◽  
Wave Model ◽  
Altimeter Data ◽  
Northern Adriatic Sea ◽  
Large Wave ◽  
Northern Adriatic ◽  
Wave Heights ◽  
One Year

Abstract. We carry out an inter comparison among four different altimeters, Cryosat, Jason2, Jason3, Sentinel-3. This is done checking the altimeter data versus the same wind and wave model results of a given area, the Mediterranean Sea, for one year period. The four datasets are consistent for wind speed, but they show substantial differences for wave heights. The verification of a Sentinel-3 pass close to coast in the Northern Adriatic Sea shows irregular spiky large wave height values close to coast. The problem worsens using high frequency altimeter data.

scholarly journals Accuracy of altimeter data in inner and coastal seas

Ocean Science ◽  
2019 ◽  
Vol 15 (2) ◽  
pp. 227-233 ◽  
Author(s):  
Luigi Cavaleri ◽  
Luciana Bertotti ◽  
Paolo Pezzutto
Keyword(s):  
Wind Speed ◽  
High Frequency ◽  
Adriatic Sea ◽  
Wave Model ◽  
Altimeter Data ◽  
Data Sets ◽  
Northern Adriatic Sea ◽  
Large Wave ◽  
Northern Adriatic ◽  
Wave Heights

Abstract. We carry out an inter-comparison of four different altimeters: Cryosat, Jason-2, Jason-3, and Sentinel-3. This inter-comparison is undertaken by checking the altimeter data against the wind and wave model results of a given area, the Mediterranean Sea, for a 1-year period. The four data sets are consistent for wind speed, but they show substantial differences with respect to wave heights. The verification of a Sentinel-3 pass close to the coast in the northern Adriatic Sea shows irregular, spiky, large, wave height values close to the coast. This problem worsens when using high-frequency altimeter data.

scholarly journals Estimation of Significant Wave Heights from ASCAT Scatterometer Data via Deep Learning Network

2021 ◽  
Vol 13 (2) ◽  
pp. 195
Author(s):  
He Wang ◽  
Jingsong Yang ◽  
Jianhua Zhu ◽  
Lin Ren ◽  
Yahao Liu ◽  
...  
Keyword(s):  
Deep Learning ◽  
Wave Height ◽  
Significant Wave Height ◽  
Incidence Angle ◽  
Ocean Waves ◽  
Global Scale ◽  
Learning Technology ◽  
Sea State ◽  
Significant Wave ◽  
Wave Heights

Sea state estimation from wide-swath and frequent-revisit scatterometers, which are providing ocean winds in the routine, is an attractive challenge. In this study, state-of-the-art deep learning technology is successfully adopted to develop an algorithm for deriving significant wave height from Advanced Scatterometer (ASCAT) aboard MetOp-A. By collocating three years (2016–2018) of ASCAT measurements and WaveWatch III sea state hindcasts at a global scale, huge amount data points (>8 million) were employed to train the multi-hidden-layer deep learning model, which has been established to map the inputs of thirteen sea state related ASCAT observables into the wave heights. The ASCAT significant wave height estimates were validated against hindcast dataset independent on training, showing good consistency in terms of root mean square error of 0.5 m under moderate sea condition (1.0–5.0 m). Additionally, reasonable agreement is also found between ASCAT derived wave heights and buoy observations from National Data Buoy Center for the proposed algorithm. Results are further discussed with respect to sea state maturity, radar incidence angle along with the limitations of the model. Our work demonstrates the capability of scatterometers for monitoring sea state, thus would advance the use of scatterometers, which were originally designed for winds, in studies of ocean waves.

scholarly journals Comprehensive Wind and Wave Statistics and Extreme Values for Design and Analysis of Marine Structures in the Adriatic Sea

2021 ◽  
Vol 9 (5) ◽  
pp. 522
Author(s):  
Marko Katalinić ◽  
Joško Parunov
Keyword(s):  
Adriatic Sea ◽  
Extreme Values ◽  
Wave Climate ◽  
Offshore Structures ◽  
Model Parameters ◽  
Peak Period ◽  
Significant Wave ◽  
Wave Statistics ◽  
Wave Heights ◽  
Almost All

Wind and waves present the main causes of environmental loading on seagoing ships and offshore structures. Thus, its detailed understanding can improve the design and maintenance of these structures. Wind and wave statistical models are developed based on the WorldWaves database for the Adriatic Sea: for the entire Adriatic Sea as a whole, divided into three regions and for 39 uniformly spaced locations across the offshore Adriatic. Model parameters are fitted and presented for each case, following the conditional modelling approach, i.e., the marginal distribution of significant wave height and conditional distribution of peak period and wind speed. Extreme significant wave heights were evaluated for 20-, 50- and 100-year return periods. The presented data provide a consistent and comprehensive description of metocean (wind and wave) climate in the Adriatic Sea that can serve as input for almost all kind of analyses of ships and offshore structures.

Wave climate change in the Gulf of Bothnia

2021 ◽  
Author(s):  
Jan-Victor Björkqvist ◽  
Jani Särkkä ◽  
Hedi Kanarik ◽  
Laura Tuomi
Keyword(s):  
Climate Change ◽  
Wave Model ◽  
Wave Climate ◽  
Atmospheric Forcing ◽  
Simulation Data ◽  
Significant Wave ◽  
Gulf Of Bothnia ◽  
Wave Heights ◽  
Significant Wave Heights ◽  
Projected Changes

&lt;p&gt;Wave climate change in the Gulf of Bothnia in 2030&amp;#8211;2059 was investigated using regional wave climate projections. For the simulations we used wave model WAM. As the atmospheric forcing for the wave model we had three global climate scenarios (HADGEM2-ES, MPI-ESM, EC-EARTH) downscaled with RCA4-NEMO regional model. The ice concentration for the wave model was obtained from NEMO ocean model simulations using the same atmospheric forcing. We used both RCP4.5 and RCP8.5 greenhouse gas scenarios. The spatial resolution of the simulation data was 1.8 km, enabling detailed analyses of the wave properties near the coast. From the simulation data we calculated statistics and return levels of significant wave heights using extreme value analysis, and assessed the projected changes in the wave climate in the Gulf of Bothnia. The projected increase in the significant wave heights is mainly due to the decreasing ice cover, especially in the Bothnian Bay. Projected changes in the most prevalent wind direction impacts the spatial pattern of the wave heights in the Bothnian Sea.&lt;/p&gt;

scholarly journals Impact of the October 2018 Storm Vaia on Coastal Boulders in the Northern Adriatic Sea

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2229 ◽  
Author(s):  
Biolchi ◽  
Denamiel ◽  
Devoto ◽  
Korbar ◽  
Macovaz ◽  
...  
Keyword(s):  
Adriatic Sea ◽  
Three Dimensional ◽  
Deep Understanding ◽  
Wave Model ◽  
Aerial Survey ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
Multidisciplinary Study ◽  
Rocky Coast ◽  
Full Force

Boulder detachment from the seafloor and subsequent transport and accumulation along rocky coasts is a complex geomorphological process that requires a deep understanding of submarine and onshore environments. This process is especially interesting in semi-enclosed shallow basins characterized by extreme storms, but without a significant tsunami record. Moreover, the response of boulder deposits located close to the coast to severe storms remains, in terms of accurate displacement measurement, limited due to the need to acquire long-term data such as ongoing monitoring datasets and repeated field surveys. We present a multidisciplinary study that includes inland and submarine surveys carried out to monitor and accurately quantify the recent displacement of coastal boulders accumulated on the southernmost coast of the Premantura (Kamenjak) Promontory (Croatia, northern Adriatic Sea). We identified recent boulder movements using unmanned aerial vehicle digital photogrammetry (UAV-DP). Fourteen boulders were moved by the waves generated by a severe storm, named Vaia, which occurred on 29 October 2018. This storm struck Northeast Italy and the Istrian coasts with its full force. We have reproduced the storm-generated waves using unstructured wave model Simulating WAves Nearshore (SWAN), with a significant wave height of 6.2 m in front of the boulder deposit area. These simulated waves are considered to have a return period of 20 to 30 years. In addition to the aerial survey, an underwater photogrammetric survey was carried out in order to create a three-dimensional (3D) model of the seabed and identify the submarine landforms associated with boulder detachment. The survey highlighted that most of the holes can be considered potholes, while only one detachment shape was identified. The latter is not related to storm Vaia, but to a previous storm. Two boulders are lying on the seabed and the underwater surveys highlighted that these boulders may be beached during future storms. Thus, this is an interesting example of active erosion of the rocky coast in a geologically, geomorphologically, and oceanologically predisposed locality.

Prediction of Safe Sea-State for Pile Driving

2005 ◽  
Author(s):  
Hamid Bazargan ◽  
Hamid Bahai ◽  
Sirous F. Yasseri ◽  
Farzad Aryana
Keyword(s):  
Pile Driving ◽  
Solution Strategy ◽  
Sea State ◽  
Significant Wave ◽  
Dynamic Analyses ◽  
Wave Heights ◽  
Significant Wave Heights ◽  
Oceanographic Data ◽  
Ne Pacific ◽  
Pile Response

In this paper vertical piles have been studied with a view to identifying the range of sea-states suitable for the safe pile driving operation. Pile configuration, including the non-linear foundation and the gap between the pile and the pile sleeve shims have been modeled using the finite elements (FE) analysis facilities within ABAQUS. Dynamic analyses of the system for various sea-states characterized by significant wave heights and mean zero upcrossing periods and modeled as a combination of several wave components, have been performed. Repeating the above procedure can generate a table of safe and unsafe sea-states. If the prediction is repeated N times from which n times proved to be safe, then it can be said that the predicted sea-state is safe with a probability of 100(n/N)%. The significant wave height (Hs) and mean zero upcrossing period (Tz) of a future sea-state of a location in NE Pacific (near 46° N 131° W) were generated using the artificial neural networks (ANNs) already trained for this purpose — the location of US National Oceanographic Data Center (NODC) Buoy 46005 is used in this study. The Hs and Tz of some future sea-states were generated from their corresponding conditional 7-parameter probability density functions (pdf’s) given some information including a number of previously measured Hs’s and Tz’s. The parameters of the pdf’s have been estimated from the outputs of 2 different 7-network sets of trained ANNs. This gives a predicted sea-state for a specific time in future. The methodology explained in this paper can identify all control parameters and offer possible solution strategy. The finding reveals that how slight changes in the design configuration can be beneficially exploited to limit the pile response.

Assessing Climate Change in the North Atlantic Wave Regimes

2020 ◽  
Author(s):  
M. Bernardino ◽  
M. Gonçalves ◽  
C. Guedes Soares
Keyword(s):  
System Integration ◽  
Wave Model ◽  
Offshore Structures ◽  
Future Climate ◽  
Wave Direction ◽  
Peak Period ◽  
Significant Wave ◽  
The North ◽  
Wave Heights ◽  
Mean Wave Period

Abstract An improved understanding of the present and future marine climatology is necessary for numerous activities, such as operation of offshore structures, optimization of ship routes and the evaluation of wave energy resources. To produce global wave information, the WW3 wave model was forced with wind and ice-cover data from an RCP8.5 EC-Earth system integration for two 30-year time slices. The first covering the periods from 1980 to 2009 represents the present climate and the second, covering the periods from 2070–2099, represents the climate in the end of the 21st century. Descriptive statistics of wind and wave parameters are obtained for different 30-year time slices. Regarding wind, magnitude and direction will be used. For wave, significant wave height (of total sea and swell), mean wave period, peak period, mean wave direction and energy will be investigated. Changes from present to future climate are evaluated, regarding both mean and extreme events. Maps of the theses statistics are presented. The long-term monthly joint distribution of significant wave heights and peak periods is generated. Changes from present to future climate are assessed, comparing the statistics between time slices.

Climatology, Variability and Extrema of Ocean Waves: The Web-Based KNMI/ERA-40 Wave Atlas

2006 ◽  
Author(s):  
Andreas Sterl ◽  
Sofia Caires
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
Wave Model ◽  
Ocean Waves ◽  
Wave Period ◽  
Web Based ◽  
Significant Wave ◽  
Wave Parameters ◽  
Wave Heights ◽  
The Web

The European Centre for Medium Range Weather Forecasts (ECMWF) has recently finished ERA-40, a reanalysis covering the period September 1957 to August 2002. One of the products of ERA-40 consists of 6-hourly global fields of wave parameters like significant wave height and wave period. These data have been generated with the Centre’s WAM wave model. From these results the authors have derived climatologies of important wave parameters, including significant wave height, mean wave period, and extreme significant wave heights. Particular emphasis is on the variability of these parameters, both in space and time. Besides for scientists studying climate change, these results are also important for engineers who have to design maritime constructions. This paper describes the ERA-40 data and gives an overview of the results derived. The results are available on a global 1.5° × 1.5° grid. They are accessible from the web-based KNMI/ERA-40 Wave Atlas at http://www.knmi.nl/waveatlas.

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