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Journal ArticleDOI

Event-Based Validation of Swell Arrival Time

23 Nov 2016-Journal of Physical Oceanography (American Meteorological Society)-Vol. 46, Iss: 12, pp 3563-3569
TL;DR: In this paper, a methodology is developed for identifying swell events and verifying swell arrival time in models from buoy data, using the continuity and pattern of wave heights during the same swell event, and the results indicate that the model has a good agreement with the observations but usually predicts an early arrival of swell, about 4 h on average.
Abstract: The arrival time of ocean swells is an important factor for offshore and coastal engineering and naval and recreational activities, which can also be used in evaluating the numerical wave model Using the continuity and pattern of wave heights during the same swell event, a methodology is developed for identifying swell events and verifying swell arrival time in models from buoy data The swell arrival time in a WAVEWATCH III hindcast database is validated with in situ measurements The results indicate that the model has a good agreement with the observations but usually predicts an early arrival of swell, about 4 h on average A histogram shows that about one-quarter of swell events arrive early and three-quarters late by comparison with the model Many processes that may be responsible for the arrival time errors are discussed, but at this stage it is not possible to distinguish between them from the available data
Citations
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Journal ArticleDOI
TL;DR: In this paper, the authors outline and highlight important gaps in understanding the Metocean processes and suggest a major observational program in the Southern Ocean This large, but poorly investigated part of the World Ocean is home to extreme weather around the year.
Abstract: The generation and evolution of ocean waves by wind is one of the most complex phenomena in geophysics, and is of great practical significance Predictive capabilities of respective wave models, however, are impaired by lack of field in situ observations, particularly in extreme Metocean conditions The paper outlines and highlights important gaps in understanding the Metocean processes and suggests a major observational program in the Southern Ocean This large, but poorly investigated part of the World Ocean is home to extreme weather around the year The observational network would include distributed system of buoys (drifting and stationary) and autonomous surface vehicles (ASV), intended for measurements of waves and air-sea fluxes in the Southern Ocean It would help to resolve the issues of limiting fetches, extreme Extra-Tropical cyclones, swell propagation and attenuation, wave-current interactions, and address the topics of wave-induced dispersal of floating objects, wave-ice interactions in the Marginal Ice Zone, Metocean climatology and its connection with the global climate

38 citations

Journal ArticleDOI
TL;DR: In this paper, a dense network of buoys along the Brazilian coast, equipped with several meteorological and oceanographic sensors, was used to study the wave characteristics in the Southern part of the South Atlantic.
Abstract: It is well known that the majority of buoy measurements are located around the US coast and along some Europeans countries. The lack of long-term and densely spaced in situ measurements in the Southern Hemisphere in general, and the South Atlantic in particular, hinders several investigations due to the lack of detailed metocean information. Here, we present an effort to overcome this limitation, with a dense network of buoys along the Brazilian coast, equipped with several meteorological and oceanographic sensors. Out of ten currently operational buoys, three are employed to present the main characteristics of waves in the Southern part of the network. For the first time, sensor characteristics and settings are described, as well as the methods applied to the raw wave data. Statistics and distributions of wave parameters, swell propagating events, comparison with a numerical model and altimeters and a discussion about the occurrence of freak waves are presented.

20 citations


Cites background from "Event-Based Validation of Swell Arr..."

  • ...Jiang et al. (2016) shows that models can be 20 h early or 20 h late compared with observed data, but usually predicts an early arrival of swell, about 4 h on average, in a distance of thousand of kilometers....

    [...]

Journal ArticleDOI
TL;DR: In this article, the propagation of ocean swells from generating regions to remote coastlines is affected by submesoscale turbulence in the surface flow field and the presence of sub-scale velocity variatio...
Abstract: The propagation of ocean swells from generating regions to remote coastlines is affected by submesoscale turbulence in the surface flow field. The presence of submesoscale velocity variatio...

13 citations

Journal ArticleDOI
TL;DR: The Australian marine research, industry, and stakeholder community has recently undertaken an extensive collaborative process to identify the highest national priorities for wind-waves res... as mentioned in this paper, which has been conducted by the Australian Marine Research, Industry, and Stakeholder Community.
Abstract: The Australian marine research, industry, and stakeholder community has recently undertaken an extensive collaborative process to identify the highest national priorities for wind-waves res...

12 citations

Journal ArticleDOI
TL;DR: In this paper, the authors dissect the wind and wave fields of such an event, by examining the winds and the wave spectra from a hindcast of the event, together with measured wave spectrum at a location offshore Sarawak, Malaysia, with the specific aim of identifying the nature of the underlying wave field that produces the spectral shape of the measured extreme sea states.

11 citations

References
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Journal ArticleDOI
TL;DR: In this article, the spectral dissipation of wind-generated waves is modeled as a function of the wave spectrum and wind speed and direction, in a way consistent with observations of wave breaking and swell dissipation properties.
Abstract: New parameterizations for the spectral dissipation of wind-generated waves are proposed. The rates of dissipation have no predetermined spectral shapes and are functions of the wave spectrum and wind speed and direction, in a way consistent with observations of wave breaking and swell dissipation properties. Namely, the swell dissipation is nonlinear and proportional to the swell steepness, and dissipation due to wave breaking is nonzero only when a nondimensional spectrum exceeds the threshold at which waves are observed to start breaking. An additional source of short-wave dissipation is introduced to represent the dissipation of short waves due to longer breaking waves. A reduction of the wind-wave generation of short waves is meant to account for the momentum flux absorbed by longer waves. These parameterizations are combined and calibrated with the discrete interaction approximation for the nonlinear interactions. Parameters are adjusted to reproduce observed shapes of directional wave spect...

709 citations

Journal ArticleDOI
TL;DR: In this paper, the wave energy balance is verified in a wide range of conditions and scales, from gentle swells to major hurricanes, from the global ocean to coastal settings using in situ and remote sensing data.
Abstract: New parameterizations for the spectra dissipation of wind-generated waves are proposed. The rates of dissipation have no predetermined spectral shapes and are functions of the wave spectrum and wind speed and direction, in a way consistent with observation of wave breaking and swell dissipation properties. Namely, the swell dissipation is nonlinear and proportional to the swell steepness, and dissipation due to wave breaking is non-zero only when a non-dimensional spectrum exceeds the threshold at which waves are observed to start breaking. An additional source of short wave dissipation due to long wave breaking is introduced to represent the dissipation of short waves due to longer breaking waves. Several degrees of freedom are introduced in the wave breaking and the wind-wave generation term of Janssen (J. Phys. Oceanogr. 1991). These parameterizations are combined and calibrated with the Discrete Interaction Approximation of Hasselmann et al. (J. Phys. Oceangr. 1985) for the nonlinear interactions. Parameters are adjusted to reproduce observed shapes of directional wave spectra, and the variability of spectral moments with wind speed and wave height. The wave energy balance is verified in a wide range of conditions and scales, from gentle swells to major hurricanes, from the global ocean to coastal settings. Wave height, peak and mean periods, and spectral data are validated using in situ and remote sensing data. Some systematic defects are still present, but the parameterizations yield the best overall results to date. Perspectives for further improvement are also given.

420 citations

Journal ArticleDOI
TL;DR: Ardhuin et al. as discussed by the authors presented a multi-scale global hindcast of ocean waves that covers the years 1994-2012, based on recently published parameterizations for wind sea and swell dissipation.

332 citations

Journal ArticleDOI
TL;DR: In this paper, the authors analyzed twice-daily wave records to yield energy spectra E$\_{i}$(f, t) for station i as functions of frequency and time, and showed that the observed propagation could be explained by the effects of Stokes interaction (section b, c, figure 38) between wave groups from a single storm.
Abstract: Six wave stations were occupied for 2$\frac{1}{2}$ months along a great circle between New Zealand and Alaska. Twice-daily wave records were analysed to yield energy spectra E$\_{i}$(f, t) for station i as functions of frequency and time. Events from major storms appear as slanting ridges in the E$\_{i}$(f, t) field; the ridge lines f$\_{i}$ = (g/4$\pi $) (t - t$\_{0}$)/$\Delta \_{i}$ determine source time, t$\_{0}$, and source distance, $\Delta \_{i}$; rough estimates of direction $\theta \_{i}$(f) were made at two stations. Twelve major events, including several from antipodal storms ($\Delta \approx $ 180 degrees) in the Indian Ocean, could be clearly tracked from station to station. Source parameters are found to be mutually consistent, and usually in accord with weather information. Cuts in E$_{i}$(f, t) along the ridges give spectra from which the effect of dispersion is removed. These were corrected for geometric spreading and island shadowing. Comparison of the corrected ridge spectra between stations indicate negligible attenuation for frequencies below 70 mc/s (less than 0$\cdot $02 dB/deg between New Zealand and Alaska), and 0$\cdot $15 dB/deg at 80 mc/s, with a considerable scatter from event to event. At higher frequencies the events disappear into a background spectrum which is remarkably uniform over the Pacific, and presumably the result of global high winds along the entire storm belt of the South Pacific. The attenuation in the near zone of the storm (within a distance comparable to the storm diameter) is estimated at 0$\cdot $2 dB/deg at 70 mc/s and 0$\cdot $4 dB/deg at 80 mc/s. Wave-wave interactions have been derived from a perturbation expansion of the Navier-Stokes equations. The computed attenuation due to interaction between wave groups from a storm is not inconsistent with observations in both the near and far zones. The observed super-exponential decay is attributed to the decrease in interaction efficiency with diminishing wave energy along the path and dispersive narrowing of the spectral peak. Interaction with background (such as the trade wind sea) is unimportant. The conclusion is that the observed propagation could be accounted for by the effects of Stokes interaction (section b, c, figure 38) between wave groups from a single storm.

324 citations

01 Jan 2010
TL;DR: In this paper, the spectral dissipation of wind-generated waves is modeled as a function of the wave spectrum, in a way consistent with observation of wave breaking and swell dissipation properties.
Abstract: New parameterizations for the spectral dissipation of wind-generated waves are proposed. The rates of dissipation have no predetermined spectral shapes and are functions of the wave spectrum, in a way consistent with observation of wave breaking and swell dissipation properties. Namely, swell dissipation is nonlinear and proportional to the swell steepness, and wave breaking only affects spectral components such that the non-dimensional spectrum exceeds the threshold at which waves are observed to start breaking. An additional source of short wave dissipation due to long wave breaking is introduced, together with a reduction of wind-wave generation term for short waves, otherwise taken from Janssen (J. Phys. Oceanogr. 1991). These parameterizations are combined and calibrated with the Discrete Interaction Approximation of Hasselmann et al. (J. Phys. Oceangr. 1985) for the nonlinear interactions. Parameters are adjusted to reproduce observed shapes of directional wave spectra, and the variability of spectral moments with wind speed and wave height. The wave energy balance is verified in a wide range of conditions and scales, from the global ocean to coastal settings. Wave height, peak and mean periods, and spectral data are validated using in situ and remote sensing data. Some systematic defects are still present, but the parameterizations probably yield the most accurate overall estimate of wave parameters to date. Perspectives for further improvement are also given.

313 citations