Patrones oceánicos y atmosféricos durante períodos de puesta previos a capturas extremas de la sardina brasilera (Sardinella brasiliensis) en el océano Atlántico sudoeste

Relative maxima and minima of landings of Brazilian sardine captured in the Southeast Brazil Bight (SBB) were compared with oceanic and atmospheric composites relative to the spawning period in December and January, prior to these landings. Atmospheric and oceanic variables such as wind stress, Ekman transport, mixing index, sea surface temperature (SST), precipitation, outgoing long wave radiation and geopotential height were analyzed, revealing distinct climatological patterns in the SBB for these extreme catches that have not been described before. The system could be characterized by cooler SST composite anomaly (SSTA) along the SBB as a response to increased cloud cover and reduced incidence of short-wave radiation, predominating one year before the Brazilian sardine catch maxima. This system can take on a different configuration in which positive SSTA condition in the SBB is associated with a less intense South Atlantic Convergence Zone displaced southwards one year before the period of minimum catch. Our results indicate that the spatial structure of the spawning habitat is influenced by specific ocean-atmosphere interactions rather than simply resulting from the choice of a stable environment. This climatic constraint strongly affects the interannual variability of the Brazilian sardine production.Los desembarcos máximos y mínimos de capturas de la sardina brasileña en la Plataforma Sudeste Brasilera (SBB) se compararon con los patrones climáticos oceánicos y atmosféricos durante períodos de puesta, en diciembre y enero. Se analizó el comportamiento climático de variables oceanicas y atmosféricas como la influencia del viento, el transporte de Ekman, el índice de mezcla, la temperatura superficial del mar (SST), las precipitaciones, la radiación ascendente de ondas largas (OLR) y la altura geopotencial. Este análisis permitió la identificación de patrones climatológicos característicos sobre la SBB, no observados en trabajos previos. Los análisis revelaron que el sistema se caracteriza por SSTA más fríos sobre la sardina como respuesta a un incremento de la nebulosidad y la reducción de la incidencia de las radiaciones de onda corta, que predominan un año antes de las máximas capturas de sardina. Este sistema puede asumir una configuración distinta en la que SSTA positivos sobre la SBB se asocian con una SACZ desplazada hacia el sur un año antes del periodo de capturas mínimas. Nuestros resultados indican que la estructura espacial del hábitat de puesta es una consecuencia de las interacciones específicas océano-atmósfera, más que de una elección de ambiente estable y que ello influencia fuertemente la variabilidad interanual en la producción de sardina brasileña

Automated Detection Algorithm for SACZ, Oceanic SACZ, and Their Climatological Features

The South Atlantic Convergence Zone (SACZ) is responsible for a large amount of the total summer precipitation over Brazil and is related to severe droughts and extreme floods over the southeast of Brazil. This paper aims to demonstrate the feasibility of an objective, simplified and automated method based on satellite outgoing longwave radiation (OLR) for South Atlantic Convergence Zone (SACZ) and oceanic SACZ (SACZOCN) detection, and characterize their climatological features. Here we developed an automated algorithm and made available the SACZ and SACZOCN dates and characteristics (intensity and size) for the first time in the literature. The method agreed with 77% of SACZ occurrences compared with 21 years of SACZ observations. The temporal criterion of permanency of the SACZ convective activity for at least 4 days was essential to differentiate the SACZ from the transient frontal systems over the Brazilian Southeast. About 30% of the SACZ days occurred in November and March, therefore the December to February period is not sufficient to fully represent its activity. A barotropic trough near the Uruguay coast influences the intensity and position of the coastal and oceanic SACZ portions. When this trough closes into a cyclonic vortex Southwest of the SACZ (CVSS) cloud band it characterizes a SACZOCN episode. SACZOCN episodes were objectively identified, being characterized by a more intense convective activity and shifted to the north. We show that some oceanic SACZ episodes are associated with extreme floods and severe droughts over Brazil, therefore its identification is important to the Brazilian society. Besides, oceanic surface currents and temperature over the Southwestern Atlantic Ocean are modified during the SACZOCN active phase. The method presented here is a viable alternative to objectively classify SACZ and SACZOCN episodes, it can be implemented operationally and used to SACZ studies in the context of climate change

Modeling the spawning strategies and larval survival of the Brazilian\ud sardine (Sardinella brasiliensis)

An Individual Based Model (IBM), coupled with a hydrodynamic model (ROMS), was used to investigate\ud the spawning strategies and larval survival of the Brazilian Sardine in the South Brazil Bight (SBB). ROMS\ud solutions were compared with satellite and field data to assess their representation of the physical\ud environment. Two spawning experiments were performed for the summer along six years, coincident\ud with ichthyoplankton survey cruises. In the first one, eggs were released in spawning habitats inferred\ud from a spatial model. The second experiment simulated a random spawning to test the null hypothesis\ud that there are no preferred spawning sites. Releasing eggs in the predefined spawning habitats increases\ud larval survival, suggesting that the central-southern part of the SBB is more suitable for larvae development\ud because of its thermodynamic characteristics. The Brazilian sardine is also capable of exploring\ud suitable areas for spawning, according to the interannual variability of the SBB. The influence of water\ud temperature, the presence of Cape Frio upwelling, and surface circulation on the spawning process\ud was tested. The Cape Frio upwelling plays an important role in the modulation of Brazilian sardine\ud spawning zones over SBB because of its lower than average water temperature. This has a direct influence\ud on larval survival and on the interannual variability of the Brazilian sardine spawning process. The\ud hydrodynamic condition is crucial in determining the central-southern part of SBB as the most suitable\ud place for spawning because it enhances simulated coastal retention of larvaeCAPESCNPq - PQ (CNPq) Project Number 304633/2012-

Análise do Acoplamento Oceano-Atmosfera em Escala Sinótica ao Longo de 33 °s nos Dias 19 e 20 de Junho de 2012

http://dx.doi.org/10.5902/2179460X1621The southern coast of Brazil is marked during winter by the presence of an oceanographic front between the Brazil Current (BC) and the Brazilian Coastal Current (BCC). The BC/BCC oceanographic front imprints intense thermal gradients between the cold (BCC) waters of the continental shelf and the warm (BC) waters of the deep ocean. This work analyses, for the first time in the known literature, the ocean-atmosphere coupling using observational data taken by ship during 19-20 June 2012 along a transect off the coast of RS State, Brazil. During the period when the data were collected, a cold (post-frontal) air mass penetrated the study region causing an elevation of the atmospheric pressure and a diminution of the air temperature. Data from radiosondes launched in both sides of the oceanographic front indicate an atmospheric boundary layer thicker and more turbulent above the BC in respect to the BCC. The heat fluxes were positive along the entire transect although presenting a big variation in magnitude. Simultaneos in situ observations of both oceanographic and meteorological parameters are necessary for the understanding of the coupled ocean-atmosphere system, having primal importance for the weather prediction.A região sul do Brasil é marcada, durante o inverno, pela presença de uma frente oceanográfica entre a Corrente do Brasil (CB) e a Corrente Costeira do Brasil (CCB). A frente oceanográfica CB/CCB imprime intensos gradientes horizontais termais entre águas frias da plataforma continental sul brasileira, dominada pela CCB, e águas quentes do oceano profundo dominadas pela CB. Esse trabalho analisa, pela primeira vez na literatura conhecida, o acoplamento entre oceano e atmosfera a partir de dados observacionais tomados por navio entre 19 e 20 de junho de 2012 ao longo de um transecto realizado na costa do estado do RS, Brasil. No período em que os dados foram coletados observou-se a entrada de uma massa de ar pós-frontal que causou uma elevação da pressão atmosférica e uma diminuição da temperatura do ar. Dados de radiossondas lançadas em ambos os lados da frente oceanográfica indicam uma camada limite atmosférica mais espessa e turbulenta sobre a CB com relação à CCB

Coupled ocean-atmosphere forecasting at short and medium time scales

Author Posting. © The Author(s), 2017. This article is posted here by permission of Sears Foundation for Marine Research for personal use, not for redistribution. The definitive version was published in Journal of Marine Research 75 (2017): 877-921, doi:10.1357/002224017823523991.Recent technological advances over the past few decades have enabled the development of fully coupled atmosphere-ocean modeling prediction systems that are used today to support short-term (days to weeks) and medium-term (10–21 days) needs for both the operational and research communities. We overview the coupling framework, including model components and grid resolution considerations, as well as the coupling physics by examining heat fluxes between atmosphere and ocean, momentum transfer, and freshwater fluxes. These modeling systems can be run as fully coupled atmosphere-ocean and atmosphere-ocean-wave configurations. Examples of several modeling systems applied to complex coastal regions including Madeira Island, Adriatic Sea, Coastal California, Gulf of Mexico, Brazil, and the Maritime Continent are presented. In many of these studies, a variety of field campaigns have contributed to a better understanding of the underlying physics associated with the atmosphere-ocean feedbacks. Examples of improvements in predictive skill when run in coupled mode versus standalone are shown. Coupled model challenges such as model initialization, data assimilation, and earth system prediction are discussed.JP acknowledges support from Office of Naval Research (ONR) grant N00014- 10-1-0300. RAA and TAS were supported through the 6.2 NRL Core Project “Coupled Ocean–Wave Prediction System” Program Element #0602435N. HS acknowledges support from ONR (N00014- 15-1-2588), NSF (OCE-f 419235), andNOAA(NA15OAR4310176). AJMwas supported by the NSF Earth System Modeling Program (OCE1419306) and the NOAA Climate Variability and Prediction Program (NA14OAR4310276). LPP is supported by CNPq’s fellowships on scientific productivity (CNPq 304009/2016-4). JA and RC were financially supported by the Oceanic Observatory of Madeira Project (M1420-01-0145-FEDER-000001-Observatório Oceânico da Madeira-OOM)

Oceanic eddy‑induced modifications to air–sea heat and CO2 fluxes in the Brazil‑Malvinas Confluence

Sea surface temperature (SST) anomalies caused by a warm core eddy (WCE) in the Southwestern Atlantic Ocean (SWA) rendered a crucial influence on modifying the marine atmospheric boundary layer (MABL). During the first cruise to support the Antarctic Modeling and Observation System (ATMOS) project, a WCE that was shed from the Brazil Current was sampled. Apart from traditional meteorological measurements, we used the Eddy Covariance method to directly measure the ocean–atmosphere sensible heat, latent heat, momentum, and carbon dioxide ( CO2) fluxes. The mechanisms of pressure adjustment and vertical mixing that can make the MABL unstable were both identified. The WCE also acted to increase the surface winds and heat fluxes from the ocean to the atmosphere. Oceanic regions at middle and high latitudes are expected to absorb atmospheric CO2, and are thereby considered as sinks, due to their cold waters. Instead, the presence of this WCE in midlatitudes, surrounded by predominantly cold waters, caused the ocean to locally act as a CO2 source. The contribution to the atmosphere was estimated as 0.3 ± 0.04 mmol m− 2 day− 1, averaged over the sampling period. The CO2 transfer velocity coefficient (K) was determined using a quadratic fit and showed an adequate representation of ocean–atmosphere fluxes. The ocean–atmosphere CO2, momentum, and heat fluxes were each closely correlated with the SST. The increase of SST inside the WCE clearly resulted in larger magnitudes of all of the ocean–atmosphere fluxes studied here. This study adds to our understanding of how oceanic mesoscale structures, such as this WCE, affect the overlying atmosphere

Constraining Southern Ocean air-sea-ice fluxes through enhanced observations

Air-sea and air-sea-ice fluxes in the Southern Ocean play a critical role in global climate through their impact on the overturning circulation and oceanic heat and carbon uptake. The challenging conditions in the Southern Ocean have led to sparse spatial and temporal coverage of observations. This has led to a “knowledge gap” that increases uncertainty in atmosphere and ocean dynamics and boundary-layer thermodynamic processes, impeding improvements in weather and climate models. Improvements will require both process-based research to understand the mechanisms governing air-sea exchange and a significant expansion of the observing system. This will improve flux parameterizations and reduce uncertainty associated with bulk formulae and satellite observations. Improved estimates spanning the full Southern Ocean will need to take advantage of ships, surface moorings, and the growing capabilities of autonomous platforms with robust and miniaturized sensors. A key challenge is to identify observing system sampling requirements. This requires models, Observing System Simulation Experiments (OSSEs), and assessments of the specific spatial-temporal accuracy and resolution required for priority science and assessment of observational uncertainties of the mean state and direct flux measurements. Year-round, high-quality, quasi-continuous in situ flux measurements and observations of extreme events are needed to validate, improve and characterize uncertainties in blended reanalysis products and satellite data as well as to improve parameterizations. Building a robust observing system will require community consensus on observational methodologies, observational priorities, and effective strategies for data management and discovery

Aplicação de dois métodos no controle de qualidade em dados coletados por estações meteorológicas automáticas de superfície

No início dos anos 90, o Brasil e a Grã-Bretanha, juntos, deram um passo, no sentido de produzir estudos microclimáticos dentro da área que compreende a floresta Amazônica, visando quantificar e verificar o impacto do desmatamento dessa floresta sobre o clima. Para isso escolheu-se três regiões para a instalação de estações meteorológicas automáticas de superfície (Estados do Amazonas, Pará e Rondônia). Cada região recebeu uma estação em uma área florestada e outra em área desmatada. Esse projeto binacional foi chamado de "ESTUDO ANGLO-BRASILEIRO DE OBSERVAÇÃO DO CLIMA DA AMAZONIA, (ABRACOS - Anglo-Braz11ian Amazonian Climate Observation Study)". Esse trabalho apresenta a aplicação de dois métodos de controle de qualidade para os dados coletados pelas estações meteorológicas automáticas de superfície. Um desses métodos leva em consideração o comportamento estatístico das variáveis coletadas, e o outro método o comportamento físico e climatológico das mesmas. Por último se faz o uso desses dados com e sem erros no cálculo da evapotranspiração, no sentido de se ver o impacto de uma informação errônea no cálculo de um parametro. O método estatístico demonstrou ter um bom potencial na detecção de erros pequenos (com tamanhos variando de 5 a 20%).(Continua). Esse método apresentou rendimentos na obtenção de erros que oscilam entre 43% e 80% para a radiação solar global. Quando se testou os valores da temperatura do ar e temperatura do bulbo úmido, obteve-se um dos melhores rendimentos do método estatístico, que chegou a 91%. Os piores desempenhos foram quando se testou a radiação refletida, alcançando-se apenas 11,1%. O método físico mostrou-se eficiente na detecção de erros maiores (30 a 90%). Os melhores desempenhos aconteceram quando se testaram as temperaturas. Em um caso o rendimento chegou a 100%. Em seu pior desempenho o método detectou apenas 20% (Teste" A" ). O método físico somente detectou informações suspeitas, dentro dos erros inseridos nas séries de dados

Equatorial Pacific dynamics : lateral mixing and tropical instability waves

This thesis presents a study focused on two main aspects of the equatorial Pacific dynamics: One is the parameterization of lateral mixing and its impact in numerical simulations of the equatorial Pacific ocean. The other is the Tropical Instability Wave (TIW) characteristics in eastern equatorial Pacific region and the associated coupled ocean-atmosphere interactions. The main objectives of this research project are achieved using both model and satellite observations. An ocean general circulation model (OGCM) is adapted to represent the tropical Pacific ocean. Experiments are performed to assess the impact of the form of lateral mixing of momentum and tracers on the state of an equatorial ocean. It is found that the large-scale structure of both the velocity and temperature fields are very sensitive to the imposed parameterization of lateral mixing in the model. With uniform values for the viscosity and diffusion coefficient across the domain, a decrease in these coefficients increases the activity of TIW, resulting in an increase in the Sea Surface Temperature of the cold tongue, and thus overcoming the cold bias often found in ocean models of the equatorial Pacific. However there is an associated increase in the strength of the Equatorial Under Current (EUC) to unrealistic levels. It is found that the strength of the EUC can be limited, whilst having little affect on the TIW activity, by applying an enhanced level of mixing in the vicinity of the equator. This enhanced mixing is used to model the effect of the observed interleaving of water masses across the equator. Descriptions of TIW variability characteristics in the tropical Pacific ocean as function of the large scale climate conditions and interannual variability, such as ENSO, are made based on satellite data. As others have found, the TIW ocean-atmosphere coupling is caused by atmospheric boundary layer (ABL) instability and mixing. Our observational results suggest that this mechanism of wind-SST coupled variability may occur not only during La Nina years, when TIWs are more active, but whenever the TIWs are active. There is evidence that the TIW activity increases when under strengthened wind stress conditions either in La Nina years or, by analogy, when numerical simulations are carried out under stronger wind stress. The coupled ocean-atmosphere experiments, using a simplified ABL scheme, under different coupling strengths, suggests that this system is able to accurately simulate the TIW atmospheric imprints using a standard coupling coefficient. The active coupling strengthening produces a negative feedback on the TIWs. The TIW activity tend to be reduced in a cooler Cold Tongue region and anomalous values reaching -0.3oC in some equatorial regions, when compared with the control (CTL) experiment. However, the mechanisms which fully explain the ABL effects in the TIWs characteristics need to be further investigated.</p