Ricardo de Camargo

Modelagem numérica de ressacas na plataforma sudeste do Brasil a partir de cartas sinóticas de pressão atmosférica na superfície

Um modelo numerico tri-dimensional, linear, barotropico e de meso-escala, e usado para a plataforma sudeste brasileira, de maneira a representar a composicao das principais componentes astronomicas de mare, sobrepostas a efeitos meteorologicos extremos, para periodos especificos de interesse. No entanto, como dados meteorologicos relativos a esta area sao muito escassos e esparsos, foi utilizada uma metodologia de fornecimento de condicoes meteorologicas para o modelo de circulacao oceânica, baseada somente em cartas sinoticas de pressao atmosferica na superficie. O campo de pressao foi bem representado, mas as intensidades calculadas para os ventos foram bem maiores do que as observadas na costa. Os resultados do modelo indicam que e possivel associar o centro de alta pressao do Atlântico Sul e as correspondentes elevacoes de superficie paralelas a linha da costa a um sistema geostrofico de circulacao oceânica. Por outro lado, a passagem de frentes frias na area induz sistemas transientes que modificam o padrao geostrofico, tambem mudando a configuracao das isolinhas de elevacao de superficie.

Caracterização de eventos extremos do nível do mar em Santos e sua correspondência com as reanálises do modelo do NCEP no sudoeste do Atlântico Sul

This work aims to identify the synoptic scale atmospheric influence over the ocean for extreme events of storm surges events in the Southeastern Brazilian coast. Time series of sea surface height at the Port of Santos as well as wind and surface pressure from the NCEP reanalysis model enclosing the South Atlantic, for period 1951-1990, were used. Seasonal variability and typical evolution of atmospheric systems were found to be associated with extreme events, very relevant for applications on prognostics and warnings to authorities. Autumn and winter are seasons with the highest occurrence of positive extreme events (40.2 % and 30.8 % respectively) and the spring and winter are the ones with negative extreme events (47.2 % and 32.3 % respectively). The results show that the storm surges events depend on low pressure systems development and persistence over the ocean, with southwesterly winds over 8 m/s, together with a continental anticyclone presence.

Simulação da propagação das nove principais componentes de maré na plataforma sudeste brasileira através de modelo numérico hidrodinámico

Este trabalho apresenta a simulacao das nove principais componentes de mare na plataforma sudeste brasileira, atraves do processamento de um modelo numerico hidrodinâmico. A area modelada se estende da Ponta do Vigia (SC) a Cabo Frio (RJ), da costa ate aproximadamente a isobata de 100 m. O modelo usado nas simulacoes e tri-dimensional, linear, barotropico e de meso escala. Cada componente principal de mare foi processada isoladamente, com o objetivo de determinar suas caracteristicas na area de interesse, especificamente suas linhas cotidais e as elipses de correntes na superficie. As componentes de mare consideradas foram: Q1, O1, P1, K1, N2, M2, S2, K2 e M3. Os mapas cotidais de amplitude e fase obtidos mostram as areas de amplificacao e de atenuacao para as ondas de mare, bem como seus sentidos de propagacao. Por outro lado, as elipses de correntes na superficie indicam o comportamento das correntes de mare na area modelada, especialmente em termos dos giros, direcoes predominantes e intensidades tipicas. Com os resultados das simulacoes, e possivel prever as elevacoes e as correntes de mare, em qualquer local desta area, e para qualquer periodo de interesse.

Modeling the Paranagua Estuarine Complex, Brazil: tidal circulation and cotidal charts

A circulacao de mare na Baia de Paranagua (Estado do Parana, sul do Brasil) foi estudada atraves do Princeton Ocean Model. O domino do modelo abrange a regiao costeira adjacente e a area estuarina, com resolucao de aproximadamente I km nas direcoes perpendicular e paralela a costa. Distribuicoes homogeneas e diagnosticas para temperatura e salinidade foram usadas e 12 constituintes de mare especificaram as elevacoes de superficie nos contornos abertos. Analises de mare de series temporais de 29 dias de elevacoes e correntes para cada ponto de grade geraram linhas cotidais de amplitude e de fase, assim como elipses de correntes, para cada constituinte. Os valores obtidos pelo modelo reproduziram satisfatoriamente as amplificacoes e defasagens observadas nas elevacoes e correntes de superficie. Fluxos residuais mostram a formacao de vortices de mare, relacionados com a geometria da costa e a topografia do fundo.

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

Numerical modeling of storm surges in the coast of Mozambique: the cases of tropical cyclones Bonita (1996) and Lisette (1997)

The coast of Mozambique is often affected by storms, particularly tropical cyclones during summer or sometimes midlatitude systems in the southern part. Storm surges combined with high freshwater discharge can drive huge coastal floods, affecting both urban and rural areas. To improve the knowledge about the impact of storm surges in the coast of Mozambique, this study presents the first attempt to model this phenomenon through the implementation of the Princeton Ocean Model (POM) in the Southwestern Indian Ocean domain (SWIO; 2–32°S, 28–85°E) using a regular grid with 1/6° of spatial resolution and 36 sigma levels. The simulation was performed for the period 1979–2010, and the most interesting events of surges were related to tropical cyclones Bonita (1996) and Lisette (1997) that occurred in the Mozambique Channel. The results showed that the model represented well the amplitude and phase of principal lunar and solar tidal constituents, as well as it captured the spatial pattern and magnitudes of SST with slight positive bias in summer and negative bias in winter months. In terms of SSH, the model underestimated the presence of mesoscale eddies, mainly in the Mozambique Channel. Our results also showed that the atmospheric sea level pressure had a significant contribution to storm heights during the landfall of the tropical cyclones Bonita (1996) and Lisette (1997) in the coast of Mozambique contributing with about 20 and 16% of the total surge height for each case, respectively, surpassing the contribution of the tide-surge nonlinear interactions by a factor of 2.

RELAÇÃO ENTRE A TEMPERATURA DA SUPERFÍCIE DO MAR E A CAMADA DE MISTURA OCEÂNICA SOB A PASSAGEM DE CICLONES EXTRATROPICAIS NO ATLÂNTICO SUDOESTE

The importance of the oceanic mixed layer (OML) variation on the sea surface temperature (SST), under the influence of atmospheric extratropical cyclones was investigated in this paper. An OML simplified model derived from HYCOM (Hybrid Coordinate Ocean Model) model, based on Kraus and Turner model, was inserted as a subroutine on the BRAMS (Brazilian Regional Atmospheric Modelling System), to update the TSM every time step in the atmospheric model. The OML-BRAMS was characterized by narrowing during the trajectories of low pressure, but has not indicated a significant deepening following the anticyclone rear frontal system. The SST calculated by the BRAMS OML showed large variations (1.0°C-5.0°C) at the initial times. However, as soon as SST has been adjusted, few variation over time occurs (1.0°C-2.5°C), with the deepening (narrowing) of OML associated with decreasing (creasing) temperature.

Tides and Wind-Driven Circulation in the Tropical and Southern Atlantic Ocean: The BRAZCOAST System

Abstract The Brazilian coast is characterized by different tidal regimes and distinct meteorological influences. The northern part has larger tidal amplitudes and is permanently affected by trade winds and tropical disturbances; the southern portion has smaller tidal amplitudes and is frequently influenced by extratropical cyclone activity. Besides these aspects, many features regarding current structure and behavior are also present, such as the equatorial system of currents, the subtropical gyre and the corresponding western boundary currents, and the Brazil-Malvinas confluence region. Within this context, efforts were made to develop the BRAZCOAST system, capable of describing the processes that determine the oceanic circulation from large to coastal scales. A customized version of the Princeton Ocean Model (POM) was implemented in a basin-scale domain covering the whole of the tropical and southern Atlantic Ocean, with 0.5° spatial resolution, as well as three nested grids with (1/12)° resolution covering the different parts of the Brazilian shelf, in a one-way procedure. POM was modified to include tidal potential generator terms and a partially-clamped boundary condition for tidal elevations. The coarse grid captured large-scale features, while the nested grids detailed local circulations affected by bathymetry and coastal restrictions. An interesting aspect at the coarse grid level was the relevance of the Weddell Sea to the location of the tidal amphidromic systems.

Efeito do detalhamento dos ventos na modelagem de agitação marítima no oeste do Atlântico Sul

This work carried out numerical simulations of gravity waves of the sea surface using the model WAVEWATCH-III version 1.18 over the Atlantic in order to evaluate the importance of detailing wind features for different sea conditions. The chosen area was delimited by parallels 18 o S and 45 o S and the meridian 35o W and 70o W, so that the center of the grid was over the RS coast. For each event, wind fields from the RAMS mesoscale model (grid of 0.34o x 0.284o and hourly output time) and from the NCEP global model (grid of 2.5o x 2.5o and temporal output every 6 hours) were inserted into the WW3 model in order to verify the influence of scales in the generation of sea surface waves. It was noted that in extreme events, the simulations overestimated the heights of the waves. Comparing to the observed in situ wind fields, it was also noticed that the integrations powered by NCEP reanalysis data showed more discrepant results than the integrations from the RAMS model. The more precise behavior when using RAMS data points out the importance of mesoscale phenomena for the generation of wave trains, which propagate in groups. During calm wind events, the wave heights were underestimated, raising two lines of action: the first is to extend the chosen domain, because this pattern seems to be associated with waves generated in a far remote region and the second is to start the WW3 with a more realistic wave field.

Classification of Extreme Cold Incursions over South America

AbstractCold-air incursion across South America present a variety of problems, sometimes by advancing to the Amazon Basin and causing agricultural losses related to extreme low temperature events. The synoptic conditions that produce cold air incursions are relatively well understood; however, the most affected region depends on the route by which cold air spreads across the continent. Therefore, the classification of extreme cold air incursions allows further understanding toward the particularities directly related to the aforementioned losses. In this work, similarities and differences among extreme cold surges were found through time series correlation of anomaly temperatures in four selected areas and compositing techniques from Era-Interim reanalysis datasets, resulting in three distinct patterns: Meridional Penetration (MP), Meridional Restriction (MR) and East Penetration (EP). The patterns identified here enable more detailed understanding of the synoptic patterns and forcing mechanisms associate...