Highly nonlinear wind waves in Currituck Sound: dense breather turbulence in random ocean waves

2018 ◽  
Vol 69 (2) ◽  
pp. 187-219 ◽  
Author(s):  
Alfred R. Osborne ◽  
Donald T. Resio ◽  
Andrea Costa ◽  
Sonia Ponce de León ◽  
Elisabetta Chirivì
Keyword(s):  
Wind Waves ◽  
Ocean Waves ◽  
Highly Nonlinear ◽  
Currituck Sound ◽  
Random Ocean Waves

Observation of wave propagation in ice using stereo imaging in the Sea of Okhostk

2021 ◽  
Author(s):  
Alberto Alberello ◽  
Takehiko Nose ◽  
Tsubasa Kodaira ◽  
Keita Nishizawa ◽  
Filippo Nelli ◽  
...  
Keyword(s):  
Sea Of Okhotsk ◽  
Wave Attenuation ◽  
Wind Waves ◽  
Arctic Basin ◽  
Ocean Waves ◽  
The Arctic ◽  
Camera System ◽  
The Sea Of Okhotsk ◽  
Wave Models ◽  
Seasonal Ice Zone

<p>Sea ice seasonally covers the Sea of Okhotsk, a marginal Arctic basin nested between Russia and Japan, but its extent is predicted to decrease by 40% by 2050 leaving larger ice free areas over which waves can form. In the highly dynamical seasonal ice zone, i.e. where waves and ice interact, ice formation and breakup, and wave attenuation mutually affect each other via complex feedback mechanisms. To shed light into these interactions, wave measurements were conducted in the winter seasonal ice zone in the Southern Okhotsk Sea, North of Hokkaido, from onboard the P/V Soya using a stereo camera system. Data show that wave energy penetrates even in high ice concentration (>85%), where contemporary wave models predict complete attenuation of wind waves. Consistently with physical experiments and field observations of waves in the Arctic and Antarctic marginal ice zones, the measurements also show that the ice cover is more effective in attenuating short wave components and, consequently, the dominant wave period in ice is significantly increased compared to corresponding open ocean waves. The present data can inform calibration of wave models in the rapidly evolving seasonal ice zone in the Sea of Okhotsk.</p>

Using Remote Sensed Data for Wave Energy Resource Assessment

2008 ◽  
Author(s):  
M. T. Pontes ◽  
M. Bruck
Keyword(s):  
Wave Height ◽  
Wave Energy ◽  
Wind Waves ◽  
Energy Resource ◽  
Ocean Waves ◽  
Resource Assessment ◽  
Altimeter Data ◽  
Zero Crossing ◽  
Frequency Wave ◽  
Buoy Data

The conversion of the energy contained in ocean waves into an useful form of energy namely electrical energy requires the knowledge at least of wave height and period parameters. Since 1992 at least one altimeter has been accurately measuring significant wave height Hs. To derive wave period parameters namely zero-crossing period Tz from the altimeter backscatter coefficient various models have been proposed. Another space-borne sensor that measures ocean waves is SAR (or the advanced ASAR) from which directional spectra are obtained. In this paper various models proposed to compute Tz from altimeter data are presented and verified against a collocated set of Jason altimeter and NDBC buoy data. A good fitting of altimeter estimates to buoy data was found. Directional spectra obtained from ENVISAT ASAR measurements were compared against NDBC buoy data. It was concluded that for the buoys that are more sensitive to long low-frequency wave components the fitting of wave parameters and spectral form is good for short spatial distances. However, since the cut-off ASAR frequency is low (reliable information is provided only for long waves) their use for wave energy resource assessment in areas where wind-waves are important is limited.

scholarly journals Wind, waves, and surface currents in the Southern Ocean: observations from the Antarctic Circumnavigation Expedition

2021 ◽  
Vol 13 (3) ◽  
pp. 1189-1209
Author(s):  
Marzieh H. Derkani ◽  
Alberto Alberello ◽  
Filippo Nelli ◽  
Luke G. Bennetts ◽  
Katrin G. Hessner ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Large Scale ◽  
Prediction Models ◽  
Wind Waves ◽  
Austral Summer ◽  
Ocean Waves ◽  
Lower Atmosphere ◽  
Surface Currents ◽  
Data Set ◽  
The Antarctic

Abstract. The Southern Ocean has a profound impact on the Earth's climate system. Its strong winds, intense currents, and fierce waves are critical components of the air–sea interface and contribute to absorbing, storing, and releasing heat, moisture, gases, and momentum. Owing to its remoteness and harsh environment, this region is significantly undersampled, hampering the validation of prediction models and large-scale observations from satellite sensors. Here, an unprecedented data set of simultaneous observations of winds, surface currents, and ocean waves is presented, to address the scarcity of in situ observations in the region – https://doi.org/10.26179/5ed0a30aaf764 (Alberello et al., 2020c) and https://doi.org/10.26179/5e9d038c396f2 (Derkani et al., 2020). Records were acquired underway during the Antarctic Circumnavigation Expedition (ACE), which went around the Southern Ocean from December 2016 to March 2017 (Austral summer). Observations were obtained with the wave and surface current monitoring system WaMoS-II, which scanned the ocean surface around the vessel using marine radars. Measurements were assessed for quality control and compared against available satellite observations. The data set is the most extensive and comprehensive collection of observations of surface processes for the Southern Ocean and is intended to underpin improvements of wave prediction models around Antarctica and research of air–sea interaction processes, including gas exchange and dynamics of sea spray aerosol particles. The data set has further potentials to support theoretical and numerical research on lower atmosphere, air–sea interface, and upper-ocean processes.

scholarly journals DIRECTIONAL SPECTRA OF OCEAN SURFACE WAVES

1976 ◽  
Vol 1 (15) ◽  
pp. 18 ◽  
Author(s):  
H. Mitsuyasu ◽  
S. Mizuno
Keyword(s):  
Angular Distribution ◽  
Frequency Spectrum ◽  
Wind Waves ◽  
Wave Spectrum ◽  
Ocean Waves ◽  
Peak Frequency ◽  
Spectral Peak ◽  
Energy Concentration ◽  
Spectral Energy ◽  
Directional Spectrum

From 1971-74 seven cruises were made to measure the directional spectrum of ocean waves by using a cloverleaf buoy. Typical sets of wave data measured both in open seas and in a bay under relatively simple conditions have been analyzed to clarify the fundamental properties of the directional spectrum of ocean waves in deep water. It is shown that the directional wave spectrum can be approximated by the product of the frequency spectrum and a unimodal angular distribution with mean direction approximately equal to that of the wind. The normalized forms of the frequency spectrum show various forms lying between the Pierson-Moskowitz spectrum and the spectrum of laboratory wind wave which has a very sharp energy concentration near the spectral peak frequency. The form of the JONSWAP spectrum is very close to that of laboratory wind waves. The concentration of the spectral energy near the spectral peak frequency seems to decrease with increasing the dimensionless fetch and the spectral form finally approaches to the Pierson-Moskowitz spectrum which can be considered as the spectrum with the least concentration of the normalized spectral energy. However, the definite relation between the shape of the normalized spectrum and the dimensionless fetch has not been obtained. Concerning the angular distribution, it is shown that the shape of angular distribution of the single-peaked wave spectrum in a generating area can be approximated by the function G(6,f) = G'(s) | cos (6-6)/2 | ** proposed originally by Longuet=Higgins et al. (1963). Here G'(s) is a normalizing function, 6 is the mean direction of the spectral component, and s is a parameter which controls the concentration of the angular distribution function.

Propagation of Steep and Breaking Short-Crested Waves: A Comparison of CFD Codes

2018 ◽  
Author(s):  
Øystein Lande ◽  
Thomas Berge Johannessen
Keyword(s):  
Wave Propagation ◽  
Wave Spectrum ◽  
Ocean Waves ◽  
Offshore Structures ◽  
Practical Reasons ◽  
Breaking Wave ◽  
Linear Wave ◽  
Wave Groups ◽  
Irregular Wave ◽  
Highly Nonlinear

Using the computational fluid domain for propagation of ocean waves have become an important tool for the calculation of highly nonlinear wave loading on offshore structures such as run-up, wave slamming and non-linear breaking wave kinematics. At present, there are many computational fluid dynamics (CFD) codes available which can be employed to calculate water wave propagation and wave induced loading on structures. For practical reasons, however, the use of these codes is often limited to the propagation of regular uni-directional waves initiated very close to the structure, or to investigating the properties and loading due to measured waves by fitting a numerical wave to a measured wave profile. The present paper focuses on the propagation of steep irregular and short crested wave groups up to the point of breaking. Indeed, this is challenging because of the highly nonlinear behavior of irregular wave groups as steepness increases and they approach the point of breaking. The complexity further increases with the introduction of short-crestedness requiring computation in a large 3-dimentional domain. Two CFD codes are used in this comparison study which are believed to be well conditioned for wave propagation, the commercial code ComFLOW (available through the ComFLOW JIP project) and the open-source code BASILISK. The primary objective of this paper to show the two CFD codes capability of recreating measured irregular wave groups, using the known linear wave components from the model test as input to fluid domain. Wave elevation is measured at several locations in the close vicinity of the focus point. The comparison is carried out for a selection of events with variation in steepness, wave spreading and wave spectrum.

System Identification of a Coupled Two DOF Moored Floating Body in Random Ocean Waves

2005 ◽  
Vol 128 (3) ◽  
pp. 191-202 ◽  
Author(s):  
R. Panneer Selvam ◽  
S. K. Bhattacharyya
Keyword(s):  
System Identification ◽  
Mass Matrix ◽  
Ocean Waves ◽  
Added Mass ◽  
Radiation Damping ◽  
Floating Body ◽  
Mooring Line ◽  
Frequency Dependent ◽  
Linear And Nonlinear ◽  
Random Ocean Waves

Dynamics of a large moored floating body in ocean waves involves frequency dependent added mass and radiation damping as well as the linear and nonlinear mooring line characteristics. Usually, the added mass and radiation damping matrices can be estimated either by potential theory-based calculations or by experiments. The nonlinear mooring line properties are usually quantified by experimental methods. In this paper, we attempt to use a nonlinear system identification approach, specifically the reverse multiple input-single output (R-MISO) method, to coupled surge-pitch response (two-degrees-of-freedom) of a large floating system in random ocean waves with linear and cubic nonlinear mooring line stiffnesses. The system mass matrix has both frequency independent and frequency dependent components whereas its damping matrix has only frequency dependent components. The excitation force and moment due to linear monochromatic waves which act on the system are assumed to be known that can either be calculated or obtained from experiments. For numerical illustration, a floating half-spheroid is adopted. The motion as well as the loading are simulated assuming Pierson-Moskowitz (PM) spectrum and these results have been analyzed by the R-MISO method yielding frequency dependent coupled added mass and radiation damping coefficients, as well as linear and nonlinear stiffness coefficients of mooring lines satisfactorily.

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