Physical processes driving the warming evolution of the Southwestern Tropical Atlantic Warm Pool.
CINTRA, M.; LENTINI, C. A. D.; SERVAIN, J.; ARAUJO, M.; MARONE, E.
Dymanics of Atmosphere and Oceans, 2015.
10.1016/j.dynatmoce.2015.08.001
Air-sea interactions, Heat budget, Mixed layer, Net heat flux, Seasonal cycle, Tropical Atlantic,
The thermodynamics of the seasonal evolution of the Southwestern Tropical Atlantic Warm Pool (hereafter SWTAWP), which is delimited by the 28 °C isotherm, is investigated using the Regional Ocean Modeling System (ROMS). Results indicate that the net heat flux is responsible for the appearance and extinction of the SWTAWP. From March to May, the SWTAWP attains its maximum development and sometimes merges with equatorial warm waters towards the African continent, whose development follows the same period. Along the equator, the combination of oceanic terms (i.e., advection and diffusion) is important to promote the separation – when it occurs – of equatorial warm waters from southwestern tropical waters, which develops off the Brazilian coast. An analysis of the relative contribution of the temperature tendency terms of the mixed layer (ML) heat budget over the appearance, development and extinction of the SWTAWP is also done. The most important term for warming and cooling inside of the ML is the net heat flux at the sea surface. The ML is heated by the atmosphere between October and April, whereas the upper ocean cools down between May and September. The highest heat content values occur during the lower-temperature period (August to October), which is linked to the deepening of the ML during this time period. The horizontal advection along the equator is important, particularly at the eastern domain, which is influenced by the cold tongue. In this area, the vertical diffusive term is also significant; however, it presents values near zero outside the equator. These results contribute to a better understanding of the behavior of the heat budget within the tropical Atlantic, as previous studies over this region focused along the equator only.
Eutrophication effects on phytoplankton size-fractioned biomass and production at a tropical estuary
GUENTHER, M.; ARAUJO, M.; FLORES-MONTES, M.; GONZALEZ-RODRIGUEZ, E.; NEUMANN-LEITÃO, S.
Marine Pollution Bulletin., v. 91(2), p. 537-547, 2015
https://doi.org/10.1016/j.marpolbul.2014.09.048
Brazil, P%–B% diagrams, Phytoplankton export, Plankton, Size structure, Trophic interactions,
Size-fractioned phytoplankton (pico, nano and microplankton) biomass and production were estimated throughout a year at Recife harbor (NE Brazil), a shallow well mixed tropical hypereutrophic estuary with short residence times but restricted water renewal. Intense loads of P-PO4 (maximum 14 μM) resulted in low N:P ratios (around 2:1), high phytoplankton biomass (B = 7.1–72 μg chl-a L−1), production (PP = 10–2657 μg C L−1 h−1) and photosynthetic efficiency (PB = 0.5–45 μg C μg chl-a−1), but no oxygen depletion (average O2 saturation: 109.6%). Nanoplankton dominated phytoplankton biomass (66%) but micro- and nanoplankton performed equivalent primary production rates (47% each). Production-biomass models indicate an export of the exceeding microplankton biomass during most of the year, possibly through grazing. The intense and constant nutrient and organic matter loading at Recife harbor is thus supporting the high microplankton productivity that is not accumulating on the system nor contributing to oxygen depletion, but supporting the whole system’s trophic web.
The first occurrence of the Order Mormonilloida (Copepoda) in the Tropical Southwest Atlantic Ocean
MELO, P. A. M. C.; MELO JUNIOR, M.; ARAUJO, M.; NEUMANN-LEITÃO, S.
Anais da Academia Brasileira de Ciências (Impresso), v. 87(1), p. 233-237, 2015
http://dx.doi.org/10.1590/0001-3765201520130394
Copepod, equatorial, Mormonilla phasma, Mormonilloida, oceanic island, zooplankton,
This communication is the first report of the occurrence of the order Mormonilloida (Mormonilla phasma) in the tropical Southwestern Atlantic Ocean. Female individuals were found in surface waters from the shelf break state of Rio Grande do Norte (Northeastern Brazil) and between depths of 60 and 100 m in the epipelagic layer around the St. Peter and St. Paul Archipelago (equatorial Atlantic). This finding extends the vertical limits for this species.
Introdução e Principais Questões Discutidas
Introdução e Principais Questões Discutidas
AMBRIZZI, T.; ARAUJO, M.
In: Painel Brasileiro de Mudanças Climáticas. (Org.). Base científica das mudanças climáticas. Contribuição do Grupo de Trabalho 1 do Painel Brasileiro de Mudanças Climáticas ao Primeiro Relatório da Avaliação Nacional sobre Mudanças Climáticas, v. 1, p. 1-496
1ª. ed., Rio de Janeiro: Universidade Federal do Rio de Janeiro
ISBN: 978-85-285-0207-7
Base Científica das Mudanças Climáticas – Volume 1 Primeiro Relatório de Avaliação Nacional
AMBRIZZI, T.; ARAUJO, M. (Eds)
COPPE, Universidade Federal do Rio de Janeiro, v. 1. 464p.
1ª ed., Rio de Janeiro: Universidade Federal do Rio de Janeiro
ISBN: 978-85-285-0207-7
O Primeiro Relatório de Avaliação Nacional (RAN1) do PBMC publicado em 2014 é composto de três volumes, correspondentes às atividades de cada Grupo de Trabalho (www.pbmc.coppe.ufrj.br). O presente documento traz uma síntese das principais contribuições para o RAN1 do Grupo de Trabalho 1 (GT1) – Bases Científicas das Mudanças Climáticas, cujo objetivo é avaliar os aspectos científicos do sistema climático e de suas mudanças.
Tropical Atlantic Contributions to Strong Rainfall Variability Along the Northeast Brazilian Coast
HOUNSOU-GBO, A.; ARAUJO, M.; BOURLES, B.; VELEDA, D. R. A.; SERVAIN, J.
Advances in Meteorology, v. 2015, p. 1-13, 2015
http://dx.doi.org/10.1155/2015/902084
Tropical Atlantic (TA) Ocean-atmosphere interactions and their contributions to strong variability of rainfall along the Northeast Brazilian (NEB) coast were investigated for the years 1974–2008. The core rainy seasons of March-April and June-July were identified for Fortaleza (northern NEB; NNEB) and Recife (eastern NEB; ENEB), respectively. Lagged linear regressions between sea surface temperature (SST) and pseudo wind stress (PWS) anomalies over the entire TA and strong rainfall anomalies at Fortaleza and Recife show that the rainfall variability of these regions is differentially influenced by the dynamics of the TA. When the Intertropical Convergence Zone is abnormally displaced southward a few months prior to the NNEB rainy season, the associated meridional mode increases humidity and precipitation during the rainy season. Additionally, this study shows predictive effect of SST, meridional PWS, and barrier layer thickness, in the Northwestern equatorial Atlantic, on the NNEB rainfall. The dynamical influence of the TA on the June-July ENEB rainfall variability shows a northwestward-propagating area of strong, positively correlated SST from the southeastern TA to the southwestern Atlantic warm pool (SAWP) offshore of Brazil. Our results also show predictive effect of SST, zonal PWS, and mixed layer depth, in the SAWP, on the ENEB rainfall.
Tropical Atlantic contributions to strong rainfall variability along the Northeast Brazilian coast
HOUNSOU-GBO, A.; ARAUJO, M.; BOURLÈS, B.; VELEDA, D.; SERVAIN, J.
Advances in Meteorology, v. 2015 (2015), Article ID 902084, 13 pages
http://dx.doi.org/10.1155/2015/902084
Tropical Atlantic (TA) Ocean-atmosphere interactions and their contributions to strong variability of rainfall along the Northeast Brazilian (NEB) coast were investigated for the years 1974–2008. The core rainy seasons of March-April and June-July were identified for Fortaleza (northern NEB; NNEB) and Recife (eastern NEB; ENEB), respectively. Lagged linear regressions between sea surface temperature (SST) and pseudo wind stress (PWS) anomalies over the entire TA and strong rainfall anomalies at Fortaleza and Recife show that the rainfall variability of these regions is differentially influenced by the dynamics of the TA. When the Intertropical Convergence Zone is abnormally displaced southward a few months prior to the NNEB rainy season, the associated meridional mode increases humidity and precipitation during the rainy season. Additionally, this study shows predictive effect of SST, meridional PWS, and barrier layer thickness, in the Northwestern equatorial Atlantic, on the NNEB rainfall. The dynamical influence of the TA on the June-July ENEB rainfall variability shows a northwestward-propagating area of strong, positively correlated SST from the southeastern TA to the southwestern Atlantic warm pool (SAWP) offshore of Brazil. Our results also show predictive effect of SST, zonal PWS, and mixed layer depth, in the SAWP, on the ENEB rainfall.
Carbon dioxide emissions from estuaries of northern and northeastern Brazil
NORIEGA, C. E. D., ARAUJO, M.
Scientific Reports 4, Article number: 6164 (2014)
10.1038/srep06164
The carbon dioxide flux through the air–water interface of coastal estuarine systems must be quantified to understand the regional balance of carbon and its transport through adjacent coastal regions. We estimated and calculated the emissions of carbon dioxide (FCO2) and the partial pressure of CO2 (pCO2) values in 28 estuarine environments at a variety of spatial scales in the northern and northeastern regions of Brazil. The results showed a mean FCO2 (water to air) of 55 ± 45 mmol·m−2·d−1. Additionally, a negative correlation between dissolved oxygen saturation and pCO2 was observed, indicating a control by biological processes and especially by organic matter degradation. This leads to increased dissolved CO2 concentration in estuarine waters which results in a pCO2 that reached 8,638 μatm. Our study suggests that northern and northeastern Brazilian estuaries act as sources of atmospheric CO2. The range of pCO2 observed were similar to those found in inner estuaries in other places around the world, with the exception of a few semi-arid estuaries (Köppen climate classification – BSh) in which record low levels of pCO2 have been detected.
Spatial and temporal variability of CO2 fluxes in tropical estuarine systems near areas of high population density in Brazil
NORIEGA, C. E. D., ARAUJO, M.; LEFÈVRE, L.; FLORES-MONTES, M.; GASPAR, F.; VELEDA, D.
Regional Environmental Change, v. 15, p. 619-630, 2015
10.1007/s10113-014-0671-3
Brazilian coast, CO2 fluxes, Population density, Tropical estuaries,
Quantifications of CO2 fluxes across the air–water interface of estuarine ecosystems are needed to understand regional carbon balances. In this study, we estimate the amount of carbon emitted from tropical estuaries of the State of Pernambuco, Brazil, using measurements of temperature, alkalinity, salinity and pH at stations located in the estuaries. The results showed that the average CO2 fluxes (+51 ± 32 mmol m−2 day−1) were mainly a product of the input of aloctone organic matter from urban centers with high population densities (~1,000 inhabitants.km−2) adjacent to the estuarine systems. This organic material increased the amount of aqueous CO2, which increased the pCO2 to 8,900 μatm. October, November and December had the highest monthly averages of the parameters associated with the carbonate system (HCO3−, dissolved inorganic carbon, aqueous carbon dioxide, CO32−, total alkalinity, temperature and pH), whereas the averages in July correlated with the CO2 fluxes. Multivariate analysis revealed that estuarine areas near the most densely populated areas (Beberibe—9,000 inhabitants.km−2 and Paratibe—3,000 inhabitants.km−2) were positively correlated with high CO2 fluxes and high pCO2.
Recent climatic trends in the tropical Atlantic
SERVAIN, J., CANIAUX, G.; KOUADIO, Y. K. ; MCPHADEN, M. J. ; ARAUJO, M.
Climate Dynamics, v. 34(11), p. 3071-3089, 2014
10.1007/s00382-014-2168-7
Climatic trends, Long-term warming, Tropical Atlantic,
A homogeneous monthly data set of sea surface temperature (SST) and pseudo wind stress based on in situ observations is used to investigate the climatic trends over the tropical Atlantic during the last five decades (1964–2012). After a decrease of SST by about 1 °C during 1964–1975, most apparent in the northern tropical region, the entire tropical basin warmed up. That warming was the most substantial (>1 °C) in the eastern tropical ocean and in the longitudinal band of the intertropical convergence zone. Surprisingly, the trade wind system also strengthened over the peirod 1964–2012. Complementary information extracted from other observational data sources confirms the simultaneity of SST warming and the strengthening of the surface winds. Examining data sets of surface heat flux during the last few decades for the same region, we find that the SST warming was not a consequence of atmospheric heat flux forcing. Conversely, we suggest that long-term SST warming drives changes in atmosphere parameters at the sea surface, most notably an increase in latent heat flux, and that an acceleration of the hydrological cycle induces a strengthening of the trade winds and an acceleration of the Hadley circulation. These trends are also accompanied by rising sea levels and upper ocean heat content over similar multi-decadal time scales in the tropical Atlantic. Though more work is needed to fully understand these long term trends, especially what happens from the mid-1970’s, it is likely that changes in ocean circulation involving some combination of the Atlantic meridional overtuning circulation and the subtropical cells are required to explain the observations.
Nutrients and carbon fluxes in the estuaries of major rivers flowing into the tropical Atlantic
ARAUJO, M.; NORIEGA , C. E. D.; LEFÈVRE, N.
Frontiers in Marine Science 27 May 2014
https://doi.org/10.3389/fmars.2014.00010
Knowledge of the seasonal variability of river discharge and the concentration of nutrients in the estuary waters of large rivers flowing into the tropical Atlantic contributes to a better understanding of the biogeochemical processes that occur in adjacent coastal and ocean systems. The monthly averaged variations of the physical and biogeochemical contributions of the Orinoco, Amazon, São Francisco, Paraíba do Sul (South America), Volta, Niger and Congo (Africa) Rivers are estimated from models or observations. The results indicate that these rivers deliver approximately 0.1 Pg C year−1 in its dissolved organic (DOC 0.046 Pg C year−1) and inorganic (DIC 0.053 Pg C year−1) forms combined. These values represent 27.3% of the global DOC and 13.2% of the global DIC delivered by rivers into the world’s oceans. Estimations of the air-sea CO2 fluxes indicate a slightly higher atmospheric liberation for the African systems compared with the South American estuaries (+10.6 ± 7 mmol m−2 day−1 and +5.4 ± 8 mmol m−2 day−1, respectively). During the high river discharge periods, the fluxes remained positive in all of the analyzed systems (average +12 ± 8 mmol m−2 day−1), except at the mouth of the Orinoco River, which continued to act as a sink for CO2. During the periods of low river discharges, the mean CO2 efflux decreased to +5.2 ± 9 mmol m−2 day−1. The updated and detailed review presented here contributes to the accurate quantification of CO2 input into the atmosphere and to ongoing studies on the oceanic modeling of biogeochemical cycles in the tropical Atlantic.
Nutrients and carbon fluxes in the estuaries of major rivers flowing into the tropical Atlantic.
ARAUJO, M.; NORIEGA , C. E. D.; LEFÈVRE, N.
Frontiers in Marine Science, v. 1, Article 10, 2014.
https://doi.org/10.3389/fmars.2014.00010
biogeochemistry, carbon dioxide, estuaries, large rivers, Tropical Atlantic,
Knowledge of the seasonal variability of river discharge and the concentration of nutrients in the estuary waters of large rivers flowing into the tropical Atlantic contributes to a better understanding of the biogeochemical processes that occur in adjacent coastal and ocean systems. The monthly averaged variations of the physical and biogeochemical contributions of the Orinoco, Amazon, São Francisco, Paraíba do Sul (South America), Volta, Niger and Congo (Africa) Rivers are estimated from models or observations. The results indicate that these rivers deliver approximately 0.1 Pg C year−1 in its dissolved organic (DOC 0.046 Pg C year−1) and inorganic (DIC 0.053 Pg C year−1) forms combined. These values represent 27.3% of the global DOC and 13.2% of the global DIC delivered by rivers into the world’s oceans. Estimations of the air-sea CO2 fluxes indicate a slightly higher atmospheric liberation for the African systems compared with the South American estuaries (+10.6 ± 7 mmol m−2 day−1 and +5.4 ± 8 mmol m−2 day−1, respectively). During the high river discharge periods, the fluxes remained positive in all of the analyzed systems (average +12 ± 8 mmol m−2 day−1), except at the mouth of the Orinoco River, which continued to act as a sink for CO2. During the periods of low river discharges, the mean CO2 efflux decreased to +5.2 ± 9 mmol m−2 day−1. The updated and detailed review presented here contributes to the accurate quantification of CO2 input into the atmosphere and to ongoing studies on the oceanic modeling of biogeochemical cycles in the tropical Atlantic.