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As ressacas do mar podem ser compreendidas como fenomenos de sobrelevacao do nivel do mar de origem astronomica e meteoceanografica que, somados a acao das ondas, geram efeitos e impactos no litoral, podendo resultar em danos e prejuizos. Considerando a forte incidencia deste fenomeno no Brasil, este artigo tem como objetivo analisar os eventos de ressaca do mar que ocorreram no estado do Rio de Janeiro, no periodo de 1948 a 2008, a partir de duas perspectivas: a primeira de âmbito geral, caracterizando o estado de mar, a frequencia, a sazonalidade e a correlacao com os fenomenos El Nino/La Nina dos eventos para todo o litoral do estado; e a segunda, destacando dois eventos de ressaca que merecem atencao especial pela quantidade de locais que sofreram danos. Materias de jornais sobre eventos de ressaca foram correlacionados com dados de reanalise de ondas do modelo Wavewatch III, dados de mare astronomica e de reanalise de mare meteorologica do SMC-Brasil. Alem disso, estes eventos tambem foram correlacionados com os dados do Indice de Oscilacao do Sul (IOS) com o objetivo de compreender a influencia ou nao dos fenomenos El Nino/ La Nina durante estes eventos. Os resultados indicaram, em eventos de ressaca, uma concentracao de ondas no quadrante sul, principalmente de direcao SSO, com predominio de ondas entre 2,5 m a 4,0 m, e periodos de pico mais significativos (120 eventos) compreendidos entre 7 s e 13s. Em relacao ao IOS, os resultados indicaram quase a mesma quantidade de ressacas em periodos com a ocorrencia de El Nino/La Nina (72 eventos), quando comparado com periodos de neutralidade (68 eventos). Comparando os fenomenos El Nino e La Nina, os resultados indicaram que 44 eventos ocorreram no periodo de La Nina, enquanto que 28 ocorreram no periodo de El Nino. Finalmente, os resultados deste artigo apresentaram as caracteristicas mais significativas dos eventos de ressacas do mar ocorridos no Rio de Janeiro ao longo de 60 anos, reunindo informacoes importantes para os agentes responsaveis pela gestao dos espacos costeiros.

A very high-resolution modelling configuration was created for the estuary of Baia de Todos os Santos – BTS, Brazil (300 to 400 m), and adjacent coastal waters (600 to 1200 m). The adoption of a multi-corner domain approach allowed the variable spatial resolution required to resolve the shelf, the bay and their interactions. Seven years were simulated using realistic oceanic, atmospheric and riverine forcing. Model validation was done against observations showing the model skill to reproduce the thermohaline field, the tidal currents, as well as the variability of the free surface at tidal and sub-tidal time scales. The results provide the first representation of the tidal wave propagation along the bay, in terms of maps of amplitudes, phases and ellipses of the barotropic currents for the main tidal constituents. By analysing the residual currents at different depths, in terms of averages over the simulation period, several prominent structures were identified and named: (i) Salvador eddy (up to 0.2 m s−1); (ii) St Antonio current (up to 0.45 m s−1); (iii) Salvador current (up to 0.5 m s−1); (iv) Itaparica eddy (up to 0.2 m s−1); (v) Ilha dos Frades southern eddy (up to 0.1 m s−1); and (vi) Ilha dos Frades northern eddy (up to 0.2 m s−1). The model set-up proved to be highly efficient and robust simulating the BTS shelf-estuary region and such an approach may be suitable to other estuarine systems.

Near-inertial oscillations (NIO) are intermittent motions with a frequency close to the inertial frequency and represent an important fraction of the energy to the currents in the upper ocean. Based on hourly velocity records at the shelf break covering the top 50 m of the water column in 5 locations and one additional location at Cabo Frio upwelling system (22° S) covering the top 200 m of water column with hourly velocity and temperature measurements, the aim of the present study is to characterize NIO along the Brazilian continental shelf break (16° S–31.5° S) describing the spatial variability of inertial energy in the mixed layer and the role of the NIO in the high-frequency hydrodynamic. The sites between 31.5° S and 28.5° S were those that revealed more near-inertial energy and higher relative importance of the near-inertial band for the variance of the currents (29% and 31%, respectively). This is associated with the proximity between the inertial frequency and the sea breeze frequency in this region, which delimits an inertial resonance area for the NIO around 30° S. The near-inertial currents between 31.5° S and 23.5° S range between 30 and 50 cm s−1 and decrease toward the locations at lower latitudes, where the range is between 5 and 25 cm s−1. Vertical shear of the order of 10−3 s−1 was reached during NIO events between 31.5° S and 23.5° S in the upper layer of the ocean (mixed layer, seasonal thermocline, and upper permanent thermocline) and can play an important role in the vertical mixing along the Brazilian continental shelf break. The NIO events analyzed at Cabo Frio upwelling system exhibited a mean duration of around 7.6 days, upward vertical phase velocity of the order of 10−1 cm s−1, vertical wavelengths of the order of 102 m, and vertical downward group velocity of the order of 10−2 cm s−1. Nevertheless, the magnitude of the vertical propagation of energy and duration of the events demonstrate the importance of NIO as a source of kinetic energy to the ocean interior.

A bacia do Rio Parana e uma das bacias hidrograficas mais importantes para o setor de energia no Brasil e, com a bacia do Rio Paraguai, faz parte da segunda maior bacia hidrografica da America do Sul, a bacia Platina. Uma analise da precipitacao sobre as bacias do Rio Parana e do Rio Paraguai no seculo XXI e realizada utilizando modelos climaticos para avaliar mudancas no ciclo hidrologico. Alem da precipitacao, este estudo utiliza uma reanalise global na avaliacao da habilidade de tres modelos climaticos globais em representar os padroes climatologicos da circulacao de verao da America do Sul que afetam o ciclo hidrologico nas duas bacias. As integracoes climaticas utilizadas estao disponiveis para o periodo historico, 1975-2004, e para as projecoes, 2041-2070 e 2071-2100. As projecoes climaticas utilizadas neste estudo sao forcadas pelo Representative Concentration Pathway (RCP) 8.5, que e a trajetoria mais extrema do Fifth Phase of the Coupled Model Intercomparison Project. A regionalizacao, que permite analises mais detalhadas nas bacias, foi feita usando o RegCM4 no âmbito do Coordinated Regional Downscaling Experiment project. O RegCM4 usou condicoes iniciais e de contorno provenientes dos seguintes modelos globais, tambem analisados neste estudo: o ESM2M do Geophysical Fluid Dynamics Laboratory; o ESM-MR do Max Planck Institute; e o HadGEM2 do Hadley Center. Para o periodo historico, HadGEM2 e ESM2M concordam melhor com a reanalise global na representacao dos padroes atmosfericos na America do Sul do que o ESM-MR. A regionalizacao do HadGEM2 apresenta menores erros na precipitacao do que as demais regionalizacoes em comparacao com as observacoes nas bacias. Quanto a diferenca entre precipitacao e evaporacao, os resultados mostram pouca alteracao no clima futuro para o mes de janeiro, exceto no sudoeste da bacia do Rio Parana na regionalizacao do ESM-MR.

International audience; The regional and coastal ocean, as a complex interface area where land, hydrology, atmosphere and ocean interact, concentrates a wide range of actors dealing with increasing socio-economic and environmental issues. Under the pressure of the impacts of climate change, forecasting the coastal ocean remains a key challenge. The international Coastal Ocean and Shelf Seas Task Team (COSS-TT) community within the OceanPredict program (former GODAE OceanView - https://www.godae-oceanview.org/) fosters multidisciplinary research efforts dedicated to the coastal ocean from the land/ocean interface to the shelf/open ocean exchange regions, in support of regional and coastal ocean forecasting. Following the first topical collection (De Mey et al. 2017), this second one offers research conducted within the COSS-TT themes. After a successful 6th international COSS-TT meeting in 2018, new steps were outlined in the integration of knowledge and capabilities in regional and coastal ocean forecasting. Two major community events defined these next steps for ocean prediction (GODAE OceanView Symposium 2019 - OceanPredict '19 - http://oceanpredict19.org/) and ocean observation (OceanObs’19 - http://www.oceanobs19.net/). The OceanObs’19 conference called for the global ocean observing community and users to “advance the frontiers of ocean observing capabilities from the coast to the deep ocean... at the boundaries between the ocean and air, seafloor, land, ice, freshwater, and human-populated areas” and to “improve the uptake of ocean data in models for understanding and forecasting of the Earth system”. These statements emphasize the need to improve the synergy between model and observations to develop regional and coastal ocean observing and forecasting capabilities (De Mey-Frémaux et al. 2019; Davidson et al. 2019). These 2018-2019 initiatives are well aligned to the scientific foundation of the United Nations Decade of Ocean Science for Sustainable Development (2021-2030). The COSS-TT community appears as a key actor of Ocean Decade Challenges related to regional and coastal ocean prediction (for example CoastPredict: Observing and Predicting the Global Coastal Ocean - https://www.coastpredict.org/).In this framework, the COSS-TT community centered this second topical collection around scientific priorities in agreement with ongoing open research fields and new identified priorities (in bold are addressed priorities in this second topical collection): (a) advances in integrated, multi-platform, long-term monitoring of physical, geochemical and biological parameters in coastal regions and coastal observatories; (b) development of fine-scale coastal ocean models; (c) downscaling approaches from large-scale to regional and coastal-scale models (methods for quantitative assessment, regional and coastal array design, downscaling approaches and data assimilation and predictability in coastal ocean forecasting systems); (d) coastal-scale atmosphere-wave-ocean couplings, (e) ecosystem response to physical drivers; (f) probabilistic approaches and risk assessment in the coastal ocean (including extreme events, impact and signature of climate change, science in support of the mitigation of coastal hazards); (g) science in support of applications in coastal oceans and (h) synergy between coastal modelling and coastal altimetry.

Ocean-estuary exchange variability was studied from 2008 to 2014 at a low latitude coastal plain estuary, Todos os Santos Bay, Brazil, near 13°S. Wind data from Climate Forecast System Reanalysis (CFSR) were used to complement the results of a high-resolution regional ocean model, ROMS. Volume exchange occurred under two distinct circulation patterns, namely Circ + and Circ − , that matched the down-estuary (spring/summer) and up-estuary (autumn/winter) wind regimes respectively. Circ + promoted water-column stratification, while Circ − lasted longer, induced more volume exchange, and reversed the estuarine circulation. In addition, a clockwise lateral circulation (looking into the estuary) occurred during Circ + , whereas a counterclockwise lateral circulation was observed during Circ − . Connectivity was observed between Jaguaripe River and Todos os Santos Bay entrance. Increases in Jaguaripe River discharge, in conjunction with up-estuary winds, promoted a northward advection of the river plume toward the main entrance of the estuary, creating a lateral density gradient over Todos os Santos Bay' western shoal. Our results demonstrate that findings about estuarine circulation at higher latitudes are applicable to low latitude estuaries when dynamical depth and/or basin's width indicate that Earth's rotation is relevant.

Upwelling and uplift events from 2008 to 2012 were analyzed at the South Equatorial Current bifurcation region and in the Salvador Canyon near 13°S. Wind data from Climate Forecast System Reanalysis (CFSR) were used to complement the results of a high-resolution regional ocean model. Upwelling and uplift events occurred predominantly during spring and summer. Previous studies have suggested upwelling implications for fisheries and fish diversity in the region. Uplift events were, on average, longer than upwelling events. Spatially, the strongest events were found over the adjacent shelf of Todos os Santos Bay and Salvador Canyon. This was also the region with the most frequent events. Analysis of forcing mechanisms revealed that wind-driven upwelling, mainly due to upward Ekman pumping, is dominant, with current-driven upwelling providing an additional contribution. Connectivity between Salvador Canyon and Todos os Santos Bay upwelling processes was observed in 20 events, preferentially during the austral summer. This connectivity was linked to a northward coastal undercurrent, which, in turn, advected upwelled/uplifted water from the canyon to the bay-adjacent shelf area. Connectivity occurred under two conditions: i) intense canyon upwelling and ii) low influence of the Brazil Current flow on the shelf. The results of this study demonstrate that wind-driven upwelling contributes directly to the connectivity phenomenon, whereas Brazil Current encroachment inhibits this process. Hence, the results shown herein are widely applicable to upwelling regions under the influence of Western Boundary Currents and/or submarine canyons where upwelling may occur.

In this study a set of 157 collocated XBT (DB/T7 type) and CTD stations distributed across three different regions of the Southern Ocean is explored using the manufacturer’s fall-rate equation (FRE), which is a classic correction method, and new correction methods to investigate how the regional environment characteristics may impact a probe’s descent and the corresponding depth estimates. Regional coefficients were estimated for all three basins and for the Southern Ocean as a whole. The manufacturer’s FRE proved to perform better in high latitudes than in the rest of the World Ocean, overestimating the true depth by only 2%. The overall depth bias was positive, further supporting the hypothesis of a regional dependence of the XBT fall rate on water temperature, which leads to a general overestimation of ocean heat content in the upper layer (~4.79 × 109 J or ~10%). The pure thermal bias was found to be mostly negative, which is likely to be related to temperature errors. However, the Southern Ocean region is notoriously undersampled when compared to the rest of the World Ocean as well, as it is associated with strong spatial and temporal variability, thus raising the overall uncertainty on that estimate. Moreover, although the manufacturer’s FRE has a satisfying performance in the Southern Ocean, the current community’s recommended correction method still leads to improved temperature values in those waters. Finally, more studies are needed in order to fully understand the XBT regional bias and its implications for climate studies in the region.

This study investigates the propagation of coastal trapped waves (CTWs) along the Brazilian continental shelf between 34°S and 11°S using in situ data combined with the outputs from a high-resolution ocean simulation with HYCOM. The CTWs generation area covers a wide region ranging from the Patagonian shelf to the southern Brazilian shelf. The spectral analysis of coastal sea level series between 54°S and 10.5°S shows three bands of high energy associated with periods from 5 to 12 days, 15–22 days, and 25–40 days. The energy of the CTWs decreases along their propagation for all frequency bands, showing a drastic reduction north of 22°S, due to abrupt variations in the width and depth of the continental shelf between Tubarao Bight and Abrolhos Bank. Their phase speed propagation varies along the coast, being faster (>25 m/s) in the southernmost region (between 42°S and 41°S), reaching ~11 m/s north of 41°S, and reducing to ~3 m/s further north (equatorward of 24°S). The free Continental Shelf Wave theory supports the notion that the intense deceleration north of 24°S can be explained by the narrowing of the continental shelf. The stratification parameter indicates that the Brazilian continental shelf has a barotropic response to wind-generated disturbances.

Estuaries may have ideal technical conditions for tidal energy conversion: strong currents and proximity to the coast and urban/industrial infrastructures. This is the case of the estuary Baia de Todos os Santos, for which a numerical tidal potential density assessment was done. This study used a high resolution numerical configuration of the ocean model ROMS forced with realistic surface and lateral forcing, as well as with tides and river discharges into the bay. Strong currents were found along the main axis of the bay, particularly at the centre and left side of the bay’s main entrance, and for a considerable time fraction. In these regions, speeds higher than 1 m s −1 were found during about 30% of the time leading to a power density around 1300 W m −2 at the surface layer, reaching peaks higher than 2500 W m −2 . The energetic flow at the left side of the inlet is affected by a remarkable sand ridge, the St. Antonio Bank, which intensifies the flow between the shoal and the coast. Operation time versus tidal power (OTP) diagrams for the bay’s entrance show that even with a sharp reduction of operation time (50%) it is still possible to extract a high portion (95%) of the total power density available. Using tidally filtered time series of speed and power density, three important oscillations were found: fortnight associated with M 2 +S 2 spring-neap cycle; semi-annual caused by the S 2 +K 2 interference and responsible for about 1/4th of the total power density; and annual oscillation related with external forcings. The residual flow contributes substantially to the total power density. This contribution is however highly spatially variable, reaching at the bay’s entrance 33% and 17% at the isobaths 10 and 25 m, respectively (at sites separated 2.5 km). Besides the bay’s entrance, some regions inside the bay were identified as potentially interesting for tidal stream energy, but its study requires observations and also additional developments in the modelling configuration.

International audience; Integration of observations of the coastal ocean continuum, from regional oceans toshelf seas and estuaries/deltas with models, can substantially increase the value ofobservations and enable a wealth of applications. In particular, models can play a criticalrole at connecting sparse observations, synthesizing them, and assisting the design ofobservational networks; in turn, whenever available, observations can guide coastalmodel development. Coastal observations should sample the two-way interactionsbetween nearshore, estuarine and shelf processes and open ocean processes, whileaccounting for the different pace of circulation drivers, such as the fast atmospheric,hydrological and tidal processes and the slower general ocean circulation and climatescales. Because of these challenges, high-resolution models can serve as connectorsand integrators of coastal continuum observations. Data assimilation approachescan provide quantitative, validated estimates of Essential Ocean Variables in thecoastal continuum, adding scientific and socioeconomic value to observations throughapplications (e.g., sea-level rise monitoring, coastal management under a sustainableecosystem approach, aquaculture, dredging, transport and fate of pollutants, maritimesafety, hazards under natural variability or climate change). We strongly recommendan internationally coordinated approach in support of the proper integration of globaland coastal continuum scales, as well as for critical tasks such as community-agreedbathymetry and coastline products.

The Brazil Current (BC) is the Western Boundary Current of the South Atlantic subtropical gyre, the dominant dynamic feature in the South Atlantic Ocean. The importance of this current lies in that it is the main conduit of subtropical waters to higher latitudes in the South Atlantic Ocean. This study assesses the structure and variability of the BC across the nominal latitude of 22° S using data from the high-density eXpendable BathyThermograph (XBT) AX97 transect and from three numerical ocean models with data assimilation. This XBT transect was implemented in 2004 and represents one of the longer-term monitoring systems of the BC in existence. The goal of this work is to enhance the understanding of the temporal and spatial variability of the ocean dynamics in the southwestern South Atlantic Ocean by using a suite of hydrographic observations and numerical model outputs. In the present work, 37 XBT transect realizations using data collected between 2004 and 2012 are used. Daily outputs covering the same time period are evaluated from Hybrid Coordinate Ocean Model with the Navy Coupled Ocean Data Assimilation (HYCOM-NCODA) with a 1/12° horizontal resolution, and GLORYS2V3 and FOAM, both with a 1/4° horizontal resolution. These Ocean Forecasting and Analysis Systems (OFAS) are able to capture the mean observed features in the 22° S region, showing a BC core confined to the west of 39° W and an Intermediate Western Boundary Current between the depths of 200 and 800 m. However, the OFAS tend to overestimate the mean BC baroclinic volume transport across the AX97 reference transect and underestimate its variability. The OFAS show that the coastal region between the coastline and the western edge of the AX97 transect plays an important role in the mean BC total transport, contributing to up to 23 % of its value, and further that this transport is not sampled by the XBT observations with its current sampling strategy. In order to understand the variability of the BC, a statistical classification of the BC is proposed, with the identification of three different events: weak, intermediate, and strong.

We review the characteristics of sea level variability at the coast focussing on how it differs from the variability in the nearby deep ocean. Sea level variability occurs on all timescales, with processes at higher frequencies tending to have a larger magnitude at the coast due to resonance and other dynamics. In the case of some processes, such as the tides, the presence of the coast and the shallow waters of the shelves results in the processes being considerably more complex than offshore. However, ‘coastal variability’ should not always be considered as ‘short spatial scale variability’ but can be the result of signals transmitted along the coast from 1000s km away. Fortunately, thanks to tide gauges being necessarily located at the coast, many aspects of coastal sea level variability can be claimed to be better understood than those in the deep ocean. Nevertheless, certain aspects of coastal variability remain under-researched, including how changes in some processes (e.g., wave setup, river runoff) may have contributed to the historical mean sea level records obtained from tide gauges which are now used routinely in large-scale climate research.

The use of Expendable Bathythermographs (XBTs) is widespread throughout the world’s oceans. 15 XBT high-density transects are located only in the Atlantic Ocean. However, the only transect that exclusively monitors the Brazil Current (BC) is the NOAA/AOML AX97 transect, running from Rio de Janeiro to Trindade Island. The BC is the Western Boundary Current linked to the circulation of the South Atlantic subtropical gyre. Surface velocity field based on the AX97 XBT data reference transect and two different altimetry datasets (AVISO and ATOBA) are compared with the objective of assessing the impact of different horizontal resolution altimetry products on averaged BC dynamical features. Furthermore, a sensibility study is performed considering different approaches to estimate BC volume transports. Data from 43 AX97 cruises, covering the period from Jan/2004 to Dec/2013 were used. AVISO (ATOBA) data are daily (weekly) and present a spatial resolution of 1/4° (1/12°). AX97 geostrophic velocity values were calculated based on XBT data using the isopycnal of σ θ = 26 . 8 kg/m3 as the reference level of no motion, whereas the altimetry surface geostrophic velocities were obtained based on maps of absolute dynamic topography. About 80.5% (74.4%) of the time, at least one altimetry dataset observed the BC core at AX97 region. ATOBA dataset presented a better performance if compared to AVISO when the BC is highly unstable. Also, in coastal areas, where the flow frequently changes direction, a high-resolution altimetry product (ATOBA) tends to represent the horizontal structure of the BC better than AVISO, where BC horizontal pattern is smoother. Finally, the merge between AX97 data and altimetry datasets presented some inconsistencies when surface currents are in opposite directions. It is recommended to combine AX97 data with another type of data acquired in deeper regions, where near-zero velocities will propagate a smaller error along the water column.

River runoff into the continental shelf affects the coastal environment in many ways: from sediment input and marine sediments resuspension to meso-scale eddies formation in case of higher river discharges. Therefore, for ocean modeling is crucial to understand the seasonal and interannual river runoff variability. Brazil stands out when it comes to riverine discharge, since 6 out of the 50 largest rivers flows within the country limits. Here, a compilation of all river discharge data provided by the Brazilian National Water Agency resulted in the identification of 97 exorheic rivers (with time series longer than 15 years), including 10 unmonitored ones which had climatologies estimated by the proposed methodology. This compilation took a considerable effort, as streamflow stations were often far from the discharge location. It was also necessary to overcome the challenge associated with the Brazilian climate heterogeneity in order to apply the regionalization method. The riverine input into the ocean was estimated at the mouth of the rivers, with the overall discharge analysis taking into consideration a division of the Brazilian Continental Shelf in five sectors. These results analyzed here are also made available for public use. Overall, the Brazilian northern continental shelf receives about 95% of the total annual river runoff (212,148 m3 s−1), followed by the northeastern continental shelf with 1.5% (3345 m3 s−1), the eastern continental shelf with 1.4% (3097 m3 s−1) and the southern continental shelf with about 1.3% (2997 m3 s−1). The southeastern continental shelf receives only 0.8% of the total discharge (1909 m3 s−1). Throughout the year, the major river discharges were observed from summer to winter months, following the different climate and precipitation patterns along the country. The interannual variability of the discharges was assessed, also looking at similarities regarding both El Nino Southern Oscillation and Pacific Decadal Oscillation.

The advancement of Coastal Ocean Forecasting Systems (COFS) requires the support of continuous scientific progress addressing: (a) the primary mechanisms driving coastal circulation; (b) methods to achieve fully integrated coastal systems (observations and models), that are dynamically embedded in larger scale systems; and (c) methods to adequately represent air-sea and biophysical interactions. Issues of downscaling, data assimilation, atmosphere-wave-ocean couplings and ecosystem dynamics in the coastal ocean are discussed. These science topics are fundamental for successful COFS, which are connected to evolving downstream applications, dictated by the socioeconomic needs of rapidly increasing coastal populations.

Upwelling events observed from the years 2003 to 2011 were analyzed. Our focus was on the Abrolhos–Campos region (ACR, 15°S–23°S), which is located along the Brazilian Margin and influenced by a western boundary current, the Brazil Current (BC). Satellite sea surface temperature, National Centers for Environmental Prediction (NCEP) and Global Forecast System (GFS) wind data were used to complement the results of a high-resolution regional oceanic model to investigate the occurrence of and the mechanisms responsible for intense upwelling events in this region. These events were more frequent from 20°S to 23°S. Over 90% of the identified upwelling events were influenced by favorable wind stress. Surface Ekman transport was found to be more important for the region from Prado (17°S) to Marataizes (21°S), whereas upward Ekman pumping played a more important role from 22°S to 23°S. Current-driven upwelling processes associated with the location of the BC as well as its velocity and meso-scale activity were also analyzed. The results showed that these mechanisms are highly influenced by the local topography. Topographic effects exerted via the acceleration of the BC are more obvious in the southern ACR, while in the Prado region, BC cyclonic meanders tend to be more relevant. Moreover, eddy-driven upwelling increases in the southward direction after the passage of the Vitoria-Trindade Ridge (20°S), an important submarine chain, which acts to constrain and modulate the southward flow of the BC.

The inner shelf circulation on the Abrolhos Bank is investigated using four years (2002–2005) of moored current and bottom pressure observations from two sites in conjunction with wind data from a nearby meteorological station. This is one of the longest projects monitoring current and sea level along the Brazilian coast. The time variability of the local circulation and main forcings are described. For the first time, both the seasonal and the interannual variabilities are addressed, as are the impact of remote forcing. The cross-shore pressure gradient in the region is mostly set up by along-shore winds, whereas the sub-inertial cross-shore momentum balance is essentially geostrophic, with smaller contributions from the cross-shore wind stress. The along-shelf momentum balance is ageostrophic and mainly occurs between the wind and bottom stresses. South-southwestward along-shore currents occur between October and January, whereas stronger north-northeastward currents are observed in fall and winter. This seasonal cycle is driven by the N–S migration of the South Atlantic High between the seasons. An increasing frequency of the southern winds and, consequently, northward currents are observed between 2002 and 2005 and are related to both the number of fronts reaching the region and the remote effect of fronts that did not cross the area. The cross-shore circulation is weak and mainly forced by the tides. It is suggested that long-period shelf waves that propagate into the region change the inner shelf current field and sea level.

The Regional Ocean Modelling System (ROMS) with embedded nesting capabilities based on AGRIF, configured with a refined grid (1/36°) and realistic forcings (6-hourly winds and surface fluxes, daily large scale oceanic forcings and tides), was implemented to describe the seasonal circulation within the Eastern Brazilian Shelf (EBS) between 10°S and 16°S and its interaction with the mesoscale dynamics associated with the Western Boundary Currents (WBC) which flow over the slope: the Brazil Current/North Brazil Current-Undercurrent (BC/NBC–NBUC), as well as the contribution of the forcing mechanisms on the generation of the shelf/slope currents. The model results show, based on the methodology adopted, that for the northern limit (10°S) the northward flow is the dominant pattern while the southward flow appears as a shallow flow confined to the top 50 m of the water column during the spring/summer seasons. The surface circulation at the inner- and mid-shelves in this region is mostly influenced by the wind forcing, while at the shelf-break the currents are mainly driven by the slope currents during all seasons. In the middle (14°S) and southern (16°S) domains, there is an alternate dominance of the southward/northward flows for the first 150 m of the water column, with the dominance of the southward (northward) flow between October–February (March–September) at 14°S. However, the annual net transport in these regions is oriented southwards. On the other hand, in the sub-surface ( ∼ 150 – 400 m ) the dominance of the northward flow is clear. At 14°S, the inner-shelf circulation is mainly driven by the wind forcing and the mid-shelf circulation is forced by both the wind and the flow over the slope, while the currents at the shelf-break are more influenced by the currents at the slope. Finally, the inner- and mid-shelf currents at 16°S are mainly driven by the wind forcing, while the shelf-break currents present a poor correlation with the wind and a strong influence of the WBC dynamics.

On 5 November 2015, the Fundao tailings dam collapsed and its content first reached River Doce and then the Atlantic Ocean by 22 November. This study focuses on the oceanic time and space patterns of river discharge dispersion. By using an ocean model together with nLw(555) and RGB images from MODIS sensors, the river plume was followed for 2 months after the arrival of the tailings at the ocean. The results show the huge effect of this accident and reveal that riverine waters may have dispersed hundreds of kilometres, reaching regions as far as the shelf in front of the city of Rio de Janeiro. The movement of the freshwater was essentially to the south in accordance with the seasonal wind regime. Episodic frontal systems, leading to wind reversion, and oceanic mesoscale features contribute to the offshore dispersion of the plume. The region more often in contact with the riverine waters was located at the inner shelf between the river mouth and the city of Vitoria, turning to the outer shelf and shelf break at lower latitudes.

The circulation at the Eastern Brazilian Shelf (EBS), near 13°S, is discussed in terms of the currents and hydrography, associating large-scale circulation, transient and local processes to establish a regional picture of the EBS circulation. The results show that the circulation within the continental shelf and slope region is strongly affected by the seasonal changes in the wind field and meso/large-scale circulation. Transient processes associated to the passage of Cold Front systems or meso-scale activity and the presence of a local canyon add more complexity to the system. During the austral spring and summer seasons, the prevailing upwelling favorable winds blowing from E–NE were responsible for driving southwestward shelf currents. The interaction with the Western Boundary Current (the Brazil Current), especially during summer, was significant and a considerable vertical shear in the velocity field was observed at the outer shelf. The passage of a Cold Front system during the springtime caused a complete reversal of the mean flow and contributed to the deepening of the Mixed Layer Depth (MLD). In addition, the presence of Salvador Canyon, subject to an upwelling favorable boundary current, enhanced the upwelling system, when compared to the upwelling observed at the adjacent shelf. During the austral autumn and winter seasons the prevailing downwelling favorable winds blowing from the SE acted to total reverse the shelf circulation, resulting in a northeastward flow. The passage of a strong Cold Front, during the autumn season, contributed not only to the strengthening of the flow but also to the deepening of the MLD. The presence of the Salvador Canyon, when subject to a downwelling favorable boundary current, caused an intensification of the downwelling process. Interestingly, the alongshore velocity at the shelf region adjacent to the head of the canyon was less affected when compared to the upwelling situation.

The Camamu Bay (CMB) is located on the narrowest shelf along the South American coastline and close to the formation of two major Western Boundary Currents (WBC), the Brazil/North Brazil Current (BC/NBC). These WBC flow close to the shelf break/slope region and are expected to interact with the shelf currents due to the narrowness of the shelf. The shelf circulation is investigated in terms of current variability based on an original data set covering the 2002–2003 austral summer and the 2003 austral autumn. The Results show that the currents at the shelf are mainly wind driven, experiencing a complete reversal between seasons due to a similar change in the wind field. Currents at the inner-shelf have a polarized nature, with the alongshore velocity mostly driven by forcings at the sub-inertial frequency band and the cross-shore velocity mainly supra-inertially forced, with the tidal currents playing an important role at this direction. The contribution of the forcing mechanisms at the mid-shelf changes between seasons. During the summer, forcings in the two frequency bands are important to drive the currents with a similar contribution of the tidal currents. On the other hand, during the autumn season, the alongshore velocity is mostly driven by sub-inertial forcings and tidally driven currents still remain important in both directions. Moreover, during the autumn when the stratification is weaker, the response of the shelf currents to the wind forcing presents a barotropic signature. The meso-scale processes related to the WBC flowing at the shelf/slope region also affect the circulation within the shelf, which contribute to cause significant current reversals during the autumn season. Currents at the shelf-estuary connection are clearly supra-inertially forced with the tidal currents playing a key role in the generation of the along-channel velocities. The sub-inertial forcings at this location act mainly to drive the weak ebb currents which were highly correlated with both local and remote wind forcing during the summer season.

An oceanic forecast system was created for the southeastern Brazilian region. A 9.5 years spin up, from January 2000 to July 2009, was used to adjust the model Regional Ocean Modelling System (ROMS) forced by oceanic climatologies and National Centers for Environmental Prediction (NCEP) surface fluxes. After this period, the system became operational with the atmospheric fluxes from the Global Forecast System (GFS). The system produces daily oceanic analysis and five days forecasts in a fully automatic manner. In addition to the routine task of running the oceanic model, this operational implementation also collects data from global datasets (maps of sea surface elevations and temperatures,profiles of temperature and salinity), for validation and improvement of the model parameterisations.Daily outputs from the operational analysis of surface temperature and altimetry, averaged over the first operational year, compare reasonably well with satellite and in-situ observations and the main features of the southeastern Brazilian dynamics are reproduced by the operational model. In the near future the system aims to incorporate the usage of large scale assimilated ocean modelling products as lateral forcing and high resolution local area atmospheric forecasts to provide the surface fluxes for the ocean model. Operational outputs and other relevant data are made available online in real time. published

Based on a vast set of in situ data, a first comprehensive overview of the oceanographic characteristics of Ba ´ia de Todos os Santos (BTS) is provided. BTS is the second largest coastal bay in Brazil (maximum area of 1223 km 2 and average depth of 9.8 m), and is located in the northeast Brazil, in the vicinity of Salvador city. The circulation inside the bay is mostly tidally driven and does not vary significantly throughout the year. On the other hand, the wet (winter) and dry (summer) seasons does alter significantly the distribution of water properties inside the BTS. During summer, the waters inside the bay have oceanic characteristics, with Tropical Water (TW) penetrating along the whole region, except for the mouth of Rio Paraguacu. The water temperature inside the bay is higher than in the coastal zone, and variations can be up to 3 ◦ C, reaching a maximum of nearly 30 ◦ C. During winter, with the increase of freshwater inflow, salinity variations of about 4 are observed between the innermost stations inside BTS and the adjacent coastal region. Salinity values inside the bay can be as low as 32.3, inhibiting the penetration of TW into the BTS, which is totally occupied by a locally formed Coastal Water (CW). An evaluation of the flushing time is also provided and shows that during summer, a 60-fold increase can be observed compared to winter (38 days). While the circulation does not vary seasonally inside the bay, the associated inner shelf is characterized by two different scenarios. During summer, the upwelling favorable easterlies drive a southwestward flow, while during winter the more frequent occurrence of cold fronts (southerly winds) tend to reverse the circulation.

The Camamu bay (BCM), located at central coast of Bahia, is a pristine region which has been the target of oil and gas activities that could put in jeopardy the whole...RESUMO. A baía de Camamu (BCM), localizada na porção central do litoral bahiano, é uma região considerada intocada que vem sendo alvo de atividades de exploração de óleo e gás, que...

The oceanic features in the eastern and southeastern brazilian shelf/slope south of 13S is investigated using ROMS (Regional Ocean Model System). The model integration was 9 years and it was forced with: i) 6-hourly synoptic atmospheric data from NCEP; ii) initial and boundary conditions from OCCAM (Ocean Climate Circulation Advanced Modelling) monthly mean climatology and iii) tidal forcing from TPXO 7.1 global data set. The model results were compared with observations, which consisted in thermodynamic MDL (Mixed Layer Depth) climatology, satellite data, measurements from tide gauges along the shelf and currents measurements values from literature. The simulated currents represented well the BC (Brazil Current)-IWBC (IntermediateWestern Boundary Current) System. The BC - IWBC system at 22S cross-shelf section, where the mean alongshelf velocity represents our simulation capability of reproducing the western boundary currents, showed poleward BC and a opposing IWBC. At this section, the BC velocity core is in 50 m with 0.41 m.s−1 and the IWBC core around 800 m with 0.15 m.s−1.

A study is made of the dynamics of slope currents that arise from a steady, constant alongshore wind over a uniform shelf. Over the first 10–20 days, the evolution of the downwelled system on an f plane is qualitatively described by linear coastal-trapped wave dynamics. After this time the thermal wind shear associated with the bottom mixed layer becomes important in the evolution of the undercurrent (UC), which is shown to be driven by the alongshore pressure gradient due to sea level. As the UC over the slope evolves, the bottom Ekman transport becomes small and negative, leading to the detachment of flow near the shelf break, localized spreading of isopycnals, and further intensification of the UC. In contrast to results obtained without bottom drag, bottom friction and boundary layer transport are shown to lead to a two- to threefold increase in cross-shelf interior transport, downwelling, and thermal wind shear. By day 60, the resultant UC has speeds of up to 15 cm s−1 and a net transport of...

Ocean forecasting and oil spill modelling and tracking are complex activities requiring specialised institutions. In this work we present a lighter solution based on the Operational Ocean Forecast Python Engine (OOFε) and the oil spill model General NOAA Operational Modelling Environment (GNOME). These two are robust relocatable and simple to implement and maintain. Implementations of the operational engine in three different regions with distinct oceanic systems, using the ocean model Regional Ocean Modelling System (ROMS), are described, namely the Galician region, the southeastern Brazilian waters and the Texas–Louisiana shelf. GNOME was able to simulate the fate of the Prestige oil spill (Galicia) and compared well with observations of the Krimsk accident (Texas). Scenarios of hypothetical spills in Campos Basin (Brazil) are illustrated, evidencing the sensitiveness to the dynamical system. OOFε and GNOME are proved to be valuable, efficient and low cost tools and can be seen as an intermediate stage towards more complex operational implementations of ocean forecasting and oil spill modelling strategies., 2

During the austral winter of 2008, thousands of penguins traveled to low latitudes along the South Atlantic coast of South America. The atmospheric and oceanic conditions from April to July 2008 may account for the penguins' unusual geographic distribution. During that period, South Atlantic coastal waters were cooler; the wind anomalies had northward and onshore components; the ocean's coastal region presented northward currents that favored the penguins to travel toward lower latitudes. This anomalous climate regime resulted from extreme meteorological frontal systems that occurred mainly during June 2008. Three consecutive extreme midlatitude cyclones produced strong wind shear that resulted in the northward oceanic flow along the South American eastern shoreline favoring the penguins to be spotted in northern tropical waters.

Submitted by Patrícia Correia (patriciacorreia@ua.pt) on 2019-03-08T15:56:19Z No. of bitstreams: 1 Marta-Almeida et al. - 2011 - OOF epsilon A Python engine for automating region.pdf: 108042 bytes, checksum: 447372a810b9b995cf3d49b4fce875f9 (MD5) Approved for entry into archive by Patrícia Correia (patriciacorreia@ua.pt) on 2019-03-08T16:11:18Z (GMT) No. of bitstreams: 1 Marta-Almeida et al. - 2011 - OOF epsilon A Python engine for automating region.pdf: 108042 bytes, checksum: 447372a810b9b995cf3d49b4fce875f9 (MD5) Made available in DSpace on 2019-03-08T16:11:18Z (GMT). No. of bitstreams: 1 Marta-Almeida et al. - 2011 - OOF epsilon A Python engine for automating region.pdf: 108042 bytes, checksum: 447372a810b9b995cf3d49b4fce875f9 (MD5) Previous issue date: 2011 The authors acknowledge financing from EU project ECOOP (FP6 Contract No. 36355) and from project REMO (Rede de Modelagem e Observaçáo Oceanográfica), funded by Petrobras. published

A nested configuration of the Regional Ocean Modeling System (ROMS) is used to study the seasonal circulation patterns and mesoscale activity of the Eastern Brazilian Margin (EBM). The EBM encompass an oligotrophic and bathymetrically complex zone in the NW South Atlantic from 8uS to 20 uS. Sea-level anomaly data are used to validate the model. Analysis of the mean circulation reveals that the EBM is dominated by seasonal and spatial dynamics of the southward Brazil Current (BC) and the northward North Brazil Undercurrent (NBUC), as well as their connection to the South Equatorial Current (SEC) dynamics. The EBM can be divided in three dynamic provinces, which are seasonally connected either by the permanent main flow or by mesoscale process. In the northern province, from 8uS to 13 uS, the NBUC is the major permanent feature and the BC is just a thin flow, confined to the top few meters. As it moves southward, the BC gets deeper and stronger. In the middle province, from 13uS to 16 uS, the dominance of the top 0–100-m circulation is seasonally alternated between the southward BC flow and the northward NBUC flow. In the southern province, from 16uS to 20 uS, the BC appears as a dominating surface feature. While on the top (0–100 m) the main current presents a pronounced seasonal and spatial variability, on subsurface waters (100–500 m) the NBUC connects the EBM continuously. Finally, analysis of the regional simulation reveals well-defined cyclonic and anticyclonic eddies. They detach from the main flow and translate along the domain throughout the year. The translation patterns are associated with the seasonal variability of the main EBM flow, with anticyclonic mesoscale features translating southward and mesoscale cyclonic features translating northward. On their pathway, these features may come very close to the margin, interacting with the near-shelf flow. published

ProcED is a MATLAB based computational package designed to facilitate the handling of a large amount of data derived from mount vessel ADCPs that monitor tidal flows and discharge in estuarine cross-sections. The package routines were written to process water current information obtained with an RD Instruments Rio Grande ADCP and its WinRiver software - version 1.03. They are capable to eliminate bad ensembles, to extrapolate current velocities for the surface and bottom blanked areas and to smooth noisy cross-profiles, enhancing the visualization of the velocity field. By performing space and time correlation between cell velocities, ProcED allows for the computation of the residual velocity field, both in the entire cross-section and in the discrete vertical profiles. Results are provided in graphical and table formats, the latter also including a table with the main flow characteristics such flooding and ebbing time, tidal elevation and current asymmetry, tidal prism and computations errors. A comparison with computations performed by WinRiver shows that ProcED discharge calculations are in average 5.5% smaller. The apparent underestimation of ProcED computations is ascribed to interpolation of the cross-profiles and to its different bottom extrapolation method. In the bottom area there is a discharge overestimation by WinRiver. ProcED é um conjunto de rotinas computacionais para ambiente MATLAB. elaborado para facilitar a manipulação da grande Quantidade de dados de correntes medidas em seção transversal com ADCP embarcado durante o ciclo da maré em região estuarina. As rotinas foram desenvolvidas para processar os dados de corrente obtidos com o ADCP Rio Grande da RD Instruments e o seu aplicativo WinRiver reversão 1.03. As rotinas tem a capacidade de eliminar dados inválidos, extrapolar as correntes para as áreas nao medidas (superfície e fundo), bem como suavizar os campos de velocidade, destacando sua visualização. Estabelecendo a correspondência espacial e temporal das células de velocidade, o ProcED) permite o cálculo das correntes residuais para toda a seção, assim como em posições específicas. As saídas do ProcED) são geradas na forma gráfica e em arquivo texto, incluindo uma tabela que apresenta as principais características do fluxo, tais como o tempo de duração da maré enchente e vazante, as velocidades média e máxima da corrente, o prisma da maré e os erros das medidas do ADCP A comparação com os cálculos efetuados pelo WinRiver mostra que as vazões determinadas pelo ProcED são 5,5% menores em média. A aparente subestimativa nas vazões obtidas com o ProcED é atribuída à diferença dos métodos de interpolação na seção transversal e na extrapolação das correntes para a região do fundo, na qual o WinRiver deve estar superestimando as vazões.

This study presents a comparative analysis of several theoretical oil spill scenarios occurring in the vicinity of the Abrolhos Reefs, a preservation area located off the Brazilian east coast. The following petroleum blocks were considered in the study: BM-CUM-1, BM-CUM-2, J-M-259 and ES-M-418, to verify the effect of the tide on the oil spreading on the continental shelf in the eastern Brazilian. The probabilistic oil spill simulations were carried out for 30 days and considered an oil of intermediate API (American Petroleum Institute) type. The simulations were performed by the OSCAR (Oil Spill Contingency and Response) model which was fed by synoptic wind data and hydrodynamic data simulated by the POM (Princeton Ocean Model) model. Two distinct seasonal scenarios were studied: the austral winter and the austral summer of 1989 and the results were discussed in terms of seasonal variability caused by the winter/summer winds and differences in mesoscale instabilities. The effect caused by tidal currents was analyzed through the comparison between simulations with and without the tides. It was concluded that the tide strongly influenced the probabilistic results of fate of oil in the spill scenarios. Many factors have influenced this fate of the spreading of oil in the absence of supra-inertial processes, such as the location of the spill, the behavior of the prevailing winds and tides in the region. The tide absence in the hydrodynamic data did not found the worst case scenarios of the spill in simulations in blocks BM-CUM-1, BM-CUM-2 and J-M-259, mainly in summer with use of intermediate oil, underestimating the real scenarios of spill. O presente estudo teve por objetivo realizar modelagens de diferentes cenários de derramamentos de óleo em blocos de petróleo (BM-CUM-1, BM-CUM-2, J-M-259 e ES-M-418) em áreas adjacentes ao Recife de Abrolhos, a fim de verificar o efeito da maré no espalhamento do óleo na plataforma leste brasileira. Foram realizadas simulações de 30 dias de derramamento de óleo de grau API (American Petroleum Institute ) intermediário, utilizando como ferramenta o modelo OSCAR (Oil Spill Contingency and Response), sendo alimentado com dados hidrodinâmicos simulados pelo modelo POM (Princeton Ocean Model ) e dados de vento sinótico simulados pelo modelo ETA, o qual foi alimentado com dados de reanálise do NCEP. Os períodos abordados foram o inverno e o verão do ano de 1989 e os resultados foram discutidos em termos das variações de intensidade e direção do espalhamento causado pelo vento sinótico de cada estação, assim como pelos processos de mesoescala e pela maré. O efeito causado pela maré foi analisado através da comparação de simulações com e sem maré. Concluiu-se que a maré influenciou fortemente nos resultados probabilísticos de destino do óleo nos cenários de derramamento. Muitos fatores mostraram influenciar nesse destino do espalhamento do óleo com a ausência dos processos supra-inerciais, como a localização geográfica do derramamento, os ventos predominantes e o comportamento da maré na região. A ausência da maré nos dados hidrodinâmicos não permitiu encontrar os cenários de pior caso de derramamento em simulações nos blocos BM-CUM-1, BM-CUM-2 e J-M-259, principalmente no verão com a utilização de óleo intermediário, subestimando os cenários reais de derramamento.