A New Approach for the Reconstruction of Significant Wave Height Time-Series

2002 ◽  
Author(s):  
Felice Arena ◽  
Silvia Puca ◽  
Brunello Tirozzi
Keyword(s):  
Time Series ◽  
San Francisco ◽  
Wave Height ◽  
Significant Wave Height ◽  
Error Function ◽  
Correlated Data ◽  
New Approach ◽  
Significant Wave ◽  
Storm Model ◽  
Good Agreement

A Neural Network (NN) model is proposed for the reconstruction of significant wave height time series, without any increase of the error of the NN output with the number of reconstructed data. The input of the NN model are correlated data, obtained from nearby stations: no data of the same series we are modelling are used. A weighted error function during the learning phase is also considered to improve the modelling of the higher significant wave height. Furthermore the equivalent triangular storm model is applied to test the ability of the NN model to reconstruct the sea storms. The comparison between actual data of a NOAA buoy moored off San Francisco (California) and the data reconstructed by NN model shows a good agreement, both during calm time periods and during storms.

The Reconstruction of Significant Wave Height Time Series by Using a Neural Network Approach

2004 ◽  
Vol 126 (3) ◽  
pp. 213-219 ◽  
Author(s):  
Felice Arena ◽  
Silvia Puca
Keyword(s):  
Neural Network ◽  
Time Series ◽  
Wave Height ◽  
Significant Wave Height ◽  
Error Function ◽  
Neural Network Approach ◽  
Significant Wave ◽  
Time Periods ◽  
Weighted Error ◽  
Storm Model

A Multivariate Neural Network (MNN) algorithm is proposed for the reconstruction of significant wave height time series, without any increase of the error of the MNN output with the number of modelled data. The algorithm uses a weighted error function during the learning phase, to improve the modelling of the higher significant wave height. The ability of the MNN to reconstruct sea storms is tested by applying the equivalent triangular storm model. Finally an application to the NOAA buoys moored off California shows a good performance of the MNN algorithm, both during sea storms and calm time periods.

“Three Sisters” Measured As a Triple Rogue Wave Group

2019 ◽  
Author(s):  
Anne Karin Magnusson ◽  
Karsten Trulsen ◽  
Ole Johan Aarnes ◽  
Elzbieta M. Bitner-Gregersen ◽  
Mika P. Malila
Keyword(s):  
Time Series ◽  
Wave Height ◽  
Significant Wave Height ◽  
Weather Conditions ◽  
Rogue Waves ◽  
Significant Wave ◽  
Wind Sea ◽  
Propagation Methods ◽  
Non Linear Propagation ◽  
Three Sisters

Abstract On November 30, 2018, our attention was caught when analyzing wave profile time series measured by a platform mounted wave sensor (a SAAB REX radar) at Ekofisk, central North Sea. The 20-minute time series had not only one, but three consecutive waves with individual heights that all were more than twice the significant wave height, the two last of them being almost equally high with a factor 2.35 to the significant wave height of 4m (from 4σ(η), over 20 minutes). Counting three rogue waves in one sequence seems to be very rare. In this study we analyze how the shape is evolving in space and time using linear and non-linear propagation methods developed by Mark Donelan [1,2] and Karsten Trulsen [3,4]. Weather conditions and characteristics of the sea state with the ‘Three Sisters’ (named the “Justine Three Sisters”) are presented. It is found that the Three Sisters occurred in a crossing sea condition, with wind sea and swell coming from directions 60 degrees apart, with about same frequency, but very different energy.

scholarly journals Capability of Jason-2 Subwaveform Retrackers for Significant Wave Height in the Calm Semi-Enclosed Celebes Sea

2020 ◽  
Vol 12 (20) ◽  
pp. 3367
Author(s):  
Kaoru Ichikawa ◽  
Xi-Feng Wang ◽  
Hitoshi Tamura
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
Leading Edge ◽  
Sea State ◽  
Significant Wave ◽  
Contamination Sources ◽  
The Pacific ◽  
Unique System ◽  
Calm Water ◽  
Good Agreement

Satellite altimetry is a unique system that provides repeated observations of significant wave height (SWH) globally, but its measurements could be contaminated by lands, slicks, or calm water with smooth surface. In this study, capability of subwaveform retrackers against 20 Hz Jason-2 measurements is examined in the calm Celebes Sea. Distances between contamination sources and Jason-2 observation points can be determined using sequentially assembled adjacent waveforms (radargram). When no contamination sources are present within a Jason-2 footprint, subwaveform retrackers are in excellent agreement with the Sensor Geophysical Data Records (SGDR) MLE4 retracker that uses full-length waveforms, except that Adaptive Leading Edge Subwaveform (ALES) retracker has a positive bias in a calm sea state (SWH < 1 m), which is not unusual in the Celebes Sea. Meanwhile, when contamination sources exist within 4.5 km from Jason-2 observation points, SGDR occasionally estimates unrealistically large SWH values, although they could be partly eliminated by sigma0 filters. These datasets are then compared with WAVEWATCH III model, resulting in good agreement. The agreement becomes worse if swells from the Pacific is excluded in the model, suggesting constant presence of swells despite the semi-enclosed nature. In addition, outliers are found related with locally-confined SWH events, which could be inadequately represented in the model.

Beyond significant wave height: A new approach for validating spectral wave models

2015 ◽  
Vol 100 ◽  
pp. 11-25 ◽  
Author(s):  
Edgar Peter Dabbi ◽  
Ivan D. Haigh ◽  
David Lambkin ◽  
Jamie Hernon ◽  
Jon J. Williams ◽  
...  
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
New Approach ◽  
Significant Wave ◽  
Wave Models

scholarly journals Changes of Significant Wave Height, Energy Period and Wave Power in Italy in the Period 1979–2018

2020 ◽  
Vol 2 (1) ◽  
pp. 3
Author(s):  
Tommaso Caloiero ◽  
Francesco Aristodemo ◽  
Danilo Algieri Ferraro
Keyword(s):  
Time Series ◽  
Wave Height ◽  
Significant Wave Height ◽  
Kendall Test ◽  
Wave Power ◽  
Mean Values ◽  
Significant Wave ◽  
Wave Energy Converters ◽  
Long Wave ◽  
Significance Levels

An analysis of a 40-year long wave time series was performed, along the coasts of Italy, in order to identify ongoing trends of two synthetic parameters, significant wave height (Hs) and energy period (Te), and of the wave power (P). First, wave data were deduced from the global atmospheric reanalysis ERA-INTERIM by the ECMWF and checked to verify their consistency. Then, a trend analysis was performed on mean values evaluated at annual and seasonal scales through the non-parametric Mann–Kendall test for three different significance levels equal to 90%, 95% and 99%. The obtained results could be useful for analyses linked to beach morphodynamics and on the identification of field installations of Wave Energy Converters (WECs).

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