Carlos Eduardo Parente

Wave Climate Analysis for a Wave Energy Conversion Application in Brazil

A variety of ocean wave energy conversion devices have been proposed worldwide considering different technology and energy extraction methods. In order to support full-scale prototype design and performance assessments of a conversion scheme to be deployed on the northern coast of Brazil, a long-term wave climate analysis is under development. A 5-year pitch-roll buoy data series has been investigated through an adaptive technique to enhance spatial resolution and allow for accurate wave directionality evaluation. Device design most influential variables such as extreme significant wave height, peak period and directionality were considered. Temporal variability in wave energy levels was particularly investigated for energy resource assessment. The major findings of this work include the narrow directional amplitude of the incident wave and higher significant wave heights of locally generated waves. The estimated energy resource levels agreed well with literature, also showing little annual fluctuation. The wave climate demonstrated to be in full agreement with the large-scale Equatorial Atlantic atmospheric variability, dominated by either local wind waves or by distant storm swells.© 2007 ASME

Extreme Wave Analysis in Campos Basin (Rio de Janeiro - Brazil) Associated With Extra-Tropical Cyclones and Anticyclones

Campos Basin is a petroleum rich area located offshore of Rio de Janeiro, Brazil. The most energetic ocean waves that reach location are generated by extra-tropical weather systems. This article studies extreme waves generated by cyclones and anticyclones, using two approaches. The first is the statistical extreme analysis applying the Peaks Over Threshold technique. The second is an evaluation of metocean features of events selected by POT as the tail of distribution. The research used 42 months of directional wave buoy measurements from 1991 to 1995 and 20 years of WAVEWATCH III simulation from 1986 to 2005, forced by NCEP/NCAR reanalysis2 surface winds. From metocean evaluation, the authors conclude that the greatest swells hitting Campos Basin come from southwest direction, peak periods over 11 seconds, generated by cyclones, occurring mainly in winter and autumn. The extreme buoy data analysis of significant wave height resulted in return values for 50 and 100 year respectively 8.77 and 9.54 meters, but with considerable uncertainty due to the short duration of data collection. Despite the limitations of Wavewatch hindcast, the methodology was able to capture the characteristics of extreme events in terms of shape of the distribution tail.Copyright

Wave observations from an array of directional buoys over the southern Brazilian coast

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.

2 – Wave climatology

This chapter describes the wave climatology in the Campos Basin, establishing classification criteria for typical wave situations in the region from measured data of winds and waves. For each established category a description with examples and general statistics is presented indicating typical values of significant wave height (Hs), spectral peak period (Tp) and dominant wave direction (θp). The most severe sea state situations for the region are also assessed, besides the situations of seas developed or limited by fetch or duration.

CLIMATOLOGIA DE ONDAS

RESUMO Este capitulo descreve a climatologia de ondas na Bacia de Campos, estabelecendo criterios de classificacao de situacoes tipicas de ondas para a regiao a partir de dados medidos de ventos e de ondas. Para cada categoria estabelecida e apresentada uma descricao com exemplos e estatistica geral, indicando valores tipicos de altura significativa (Hs), periodo de pico espectral (Tp) e direcao dominante de onda (θp). Sao tambem avaliadas as situacoes mais severas de estados de mar para a regiao, alem das situacoes de mares desenvolvidos e limitados por pista ou duracao.

Técnicas Ópticas para Identificação de Mares Regulares Cruzados

A new optical technique is presented and applied to measure regular, bichromatic surface waves propagating in different directions in a tank. The method is based on the patterns of spatio-temporal variations of brightness over sequential frames. A single camera is employed, allowing a simple and straightforward configuration well-suited for operational applications, therefore avoiding the technical complications typical of stereoscopic measurements. The initial results are promising, with directions of propagation and wave periods well defined for each wave train.

Identificação de período e direção de ondas monocromáticas através do processamento de imagens ópticas

A new methodology to estimate the period and direction of monochromatic surface gravity waves is presented based on the processing of a sequence of images. The analysis focuses on the spatial-temporal variability of brightness on the image plane. One camera only is employed to record the water surface. The main motive is to come up with a simplified and practical configuration which allows its operational implementation either on the laboratory or on oil platforms or on top of buildings. The promising results correspond to experiments in a monochromatic wave tank. The image processing technique has proven to be a valuable tool for wave measurements.

A New Technique to Visualize Metocean Parameters

This paper presents a technique (PLEDS) to plot the evolution of a metocean parameter against time, distance or other independent variable, allowing a much clear understanding of the underlying process. The technique has been applied to waves, winds, currents, tides and underwater acoustics.Copyright