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.

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The growth of surface gravity waves is investigated in an open sea region dominated by swell. An extensive database was collected by the Brazilian Oil Company during the South Atlantic Deep Water Program (PROCAP) in Campos Basin, off coast of Rio de Janeiro. This is the most important petrolic basin in Brazil where tens of drilling platforms are located. The data set contains over 5800 directional wave spectra measured by a heave-pitch-roll buoy in conjunction with meteorological data. A spectral approach is applied in a novel method for the partitioning of sea from swell and for the adjustment of the spectral parameters. The wave growth is investigated and the regression laws of the windsea extracted from the swell-contaminated spectra are compared to earlier works in sheltered areas. It is shown that, on the grounds of the equilibrium range theory, the high-frequency spectral level (the alpha parameter) scale with the reciprocal wave age in the same manner as in unimodal swell-free spectra.

Typical oceanographic instruments are expensive, complex to build, and hard to deploy and require constant and specialized maintenance. In this paper, we present a cheap and simple technique to estimate a three-dimensional surface elevation map, η(x,y,t), the directional spectrum, and the main sea state parameters using inexpensive smartphones. The proposed methodology uses Time Lagged Cross Correlation (TLCC) between the audio signals from two independent video records to perform the frame synchronization. This makes the system much easier to deploy, where the main requirement is a fixed or moving platform close to the sea. The time records are mostly limited by the equipment storage space and battery life, although it can be easily replaced or recharged. Here, we pose the basis for an inexpensive yet powerful stereo reconstruction device and discuss its capabilities and limitations. The smartphone system capabilities were illustrated here by near shore experiment, at Leme beach in the Southeast of Brazil, and the results were compared against a pressure sensor. For this particular setup, the root mean square error in terms of significant wave height is of the order of 11% with perfect estimation of the peak period. The results are promising and demonstrate the validity and applicability of the technique.

[1] One year of directional buoy measurements comprising the period from May 1994 to April 1995 acquired in deep ocean waters by an offshore heave-pitch-roll buoy are used for the assessment of the directional wave spectra retrieved from synthetic aperture radar (SAR) images using the Max-Planck-Institut (MPI) scheme. SAR is the only sensor so far deployed from satellites that can provide measurements of the directional wave spectrum with high spatial and temporal coverage when operating in the so-called SAR wave mode. Millions of SAR wave mode imagettes have been and are still being acquired over all oceanic basins yielding a powerful data set for investigating wind waves. However, directional spectral information retrieved from SAR images has not yet been assessed against in situ measurements. For the first time, detailed validations of the main wave parameters, that is, significant wave height, mean direction of propagation, and mean wavelength, are performed. It is shown that in terms of these parameters the first-guess spectra taken from the wave model WAM are in better agreement with the buoy measurements than the MPI scheme retrievals. When considering only the longer waves in the part of the spectrum observed by SAR, on the other hand, the algorithm performs at least as well as the third-generation WAM wave model. In addition to the limitations of the MPI scheme in extending the spectral information beyond the high wave number cut-off, an observed misinterpretation of wind sea energy as swell by the MPI scheme is shown to be caused by the use of a quasi-linear approximation of the imaging model in the numerical iteration procedure.Citation: Violante-Carvalho, N., I. S. Robinson, and J. Schulz-Stellenfleth (2005), Assessment of ERS synthetic aperture radar wave spectra retrieved from the Max-Planck-Institut (MPI) scheme through intercomparisons of 1 year of directional buoy measurements,

Rapizo, H.; d'Avila, V.; Violante-Carvalho, N.; Pinho, U.; Parente C.E., and Nascimento, F., 0000. Simple techniques for retrieval of wind wave periods and directions from optical images sequences in wave tanks. Journal of Coastal Research, 00(0), 000-000. Coconut Creek (Florida), ISSN 0749-0208.Optical techniques are potentially suitable for overcoming some of the limitations faced by single-point sensors, like buoys, in retrieving spatial properties of wind-generated waves. However, most of the approaches that have been addressed in the literature employ complex configurations that use a coupling system between cameras, making its implementation difficult. This article describes simple techniques for measuring the period and direction of multimodal, regular waves, employing a single, commonly available camera. Furthermore, there is no special requirement for light conditions, making its implementation feasible, in both indoor and outdoor environments. Several tests were conducted in a multidirectional tank, varying the steepness and direction of the waves. The optical measurements were in good agreement, especially for waves from moderate to greater steepness. The techniques described here could be employed as a preliminary step before tackling more-complex configurations, for instance, as a priori information on the main wave modes.