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Increased N deposition has been identified as a current global change concern for biodiversity and human health, and excess reactive nitrogen due to human activity has had numerous effects on terrestrial and aquatic ecosystems in the Northern Hemisphere. However, very little is known about the magnitude of deposition or its impacts in ecosystems outside of North America and Europe. There are a number of reasons for this discrepancy, centered on: the lack of monitoring and long-term measurements of both wet and dry N deposition; the range of tropical and aridland ecosystems with very different potential responses to increased N deposition and that are currently without substantial impact; the prevalence of fire as a driver of nutrient cycles in savannas and grasslands; and the intense concentration of human activity in vast urban areas. Currently, compared to other human impacts such as land-use change (i.e. deforestation), agricultural expansion and intensification, urbanization and climate change, N deposition effects are relatively localized and at present, largely unrealized. In addition, many areas outside of North America and Europe suffer from substantial nitrogen deficits, which highlight the necessity for establishing appropriate region-specific research priorities. While a solid understanding of the potential impacts on N deposition in Southern Hemisphere ecosystems in the next century is important, it may be most prudent to focus on mitigation that improves agricultural nitrogen use efficiency and conservation of natural ecosystems rather than critical loads, with policies that demonstrate corollary benefits to reduce excess nitrogen input in Southern Hemisphere aquatic and terrestrial ecosystems.

Os modelos baseados em agentes possibilitam tratar indivíduos, organizações e instituições representando a interação dos atores entre si, e entre os atores com o ambiente. Este trabalho conceitua tais relações e explora o exemplo da moratória da soja, pacto que tem balizado o mercado da soja na região amazônica, aplicando os conceitos discutidos. ABSTRACT: Agent-based models allow treats individuals, organizations and institutions representing the interaction of actors among themselves, and among the actors with the environment. This paper conceptualizes such relations and explores the example of moratorium soybean pact that has marked out the soybean in the Amazon region applying the discussed concepts.

Mudanças de uso e cobertura da terra resultam de complexas interações sociais e biofísicas que podem causar impactos em escalas locais e globais despertando, assim, crescente interesse da comunidade científica. Os modelos baseados em agentes têm se mostrado uma alternativa interessante para representar a heterogeneidade dos atores e as interações entre eles. No entanto, alguns conceitos precisam ser estabelecidos para a utilização desta abordagem, em especial as relações entre os atores e o ambiente, representadas computacionalmente por agentes e células, respectivamente. Este trabalho conceitua essas relações.

A large amount of water vapor reaches the rainy South American subtropics coming from the Tropical Atlantic Ocean through a pathway of moisture flow that goes over Amazonia before it veers southwards east of the Andean slopes. While over Amazonia this moisture takes part in the forest’s hydrological cycle, so that it could potentially be altered by large scale deforestation. It is reasonable to expect a priori a greater effect during the dry season, when the forest relies on its elaborate root system to guarantee high evapotranspiration. A large body of pre-existing work shows that the moisture brought via this pathway is crucial to fuel precipitation and the development of important weather systems in the region. However, it is important to investigate whether this moisture flow is in excess or acting as a limiting condition for precipitation. In the first case, a reduction in the flow would not translate into diminished rainfall and vice-versa, all other factors remaining the same. This work consists of a quantitative study of the inter-dependence between the moisture flow leaving Amazonia and subtropical rainfall, throughout the year. To this end, moisture flow leaving Amazonia is correlated to subtropical rainfall over the continent for a 22 year period. Correlations are moderately high during the dry season (July August) and the rainy season (November to March), and low in the remaining months, considered transition seasons. Each of the 22 dry seasons are individually considered so as to understand the origin of the correlations. Three seasons are found when a positive rainfall anomaly in the continent’s subtropics is accompannied by an anomalous moisture flow all the way from the tropical Atlantic into the region and three years when the opposite is observed. In other years rainfall anomalies are accompanied by qualitatively different anomalous flow patterns, which do not exhibit an important alteration of the moisture coming from Amazonia.

Grande parte das chuvas subtropicais na América do Sul são alimentadas por transporte de umidade de grande escala. No verão grande parte deste escoamento vem do Atlântico tropical e passa sobre a Amazônia antes de rumar para o sul. Neste trabalho buscam-se as principais vias de transporte de umidade para os subtrópicos ao longo do ano. Uma pergunta de interesse é se e quando a floresta Amazônica e/ou outras regiões continentais atuam como fonte de umidade para este escoamento. Analisam-se também as contribuições por parte dos fluxos médios mensais e dos transientes para este escoamento.

Analytical macroeconomic scenarios are currently the most common approach to assist in the development and evaluation of economic policies. Reproducing and evaluating the results found by analytic models is one major hurdle to be overcome by social simulation on its early development in any specific knowledge area. This work describes an initial step toward moving from algebraic input-output economic models to agent-based models, in order to get more flexibility, adding decision capabilities to the agents and exploring more complex scenarios. We study economic scenarios of carbon credits for reducing deforestation in a region of Para state, in the Brazilian Amazonia. The objective is to investigate the underlying assumptions of the analytic model through an agent-based approach, deriving new challenges to be tackled by future agent-based models.

Despite current state-of-the art global climate model (GCMs) ability to simulate well the large scale state of the global climate, there is significant variation in future climate projections of precipitation and temperature changes in South America. In order to adequately assess the possible impacts and national vulnerabilities of climate changes, full consideration of these variations in projections is of vital importance. As a starting point for this, here we use a large ensemble of simulations with the HadCM3 climate model, where each ensemble member incorporates different but plausible versions of the parameterisations of important physical processes, is used to assess the potential impact of climate change on precipitation and temperature over South America and explore the uncertainties associated with the various model parameterisations. Particular attention is paid to the general seasonal characteristics, for example the South Atlantic Convergence Zone which modulates summer rainfall over most of the continent. The changes simulated with the Eta regional model forced with of these GCM ensemble members are also reported.

An overview of the international PIRATA project over the tropical Atlantic and its impacts on the development of basin scale oceanographic research in Brazil are presented. In a nutshell, the PIRATA project is a consortium between Brazil, France and the United States for the establishment of a moored research array over the tropical Atlantic to monitor the ocean-atmosphere interface and the upper layer of the ocean. The array was designed to study the principal modes of interannual variability of the tropical Atlantic climate, namely the equatorial and the meridional modes. PIRATA data have been used by many, with more than 300,000 data files distributed via internet during the last ten years, with 97,000 files distributed in 2008 alone. The array was inaugurated with 12 ATLAS moored buoys along the equator and the meridians 38W and 10W in 1998, and grew into a 18 moored systems (see Figure 1) after the establishment of the SW extension in 2005 and the NE extension in 2008. In addition to the surface meteorological and upper ocean data measured by the ATLAS systems, the PIRATA project also counts with one ADCP mooring at 0N, 23W, tide gauges at São Tomé and Prince, and at Saint Peter and Saint Paul archipelago, in addition to pig backing sensors to monitor CO2 and O2, also indicated in Figure 1. In addition, the PIRATA array yearly maintenance cruises, done by each of Brazil, France, and the USA, have been used as a platform of opportunity to collecting extra atmospheric and oceanographic data. Such time series constitute an extremely valuable body of information from sparse oceanic data areas, which have been used to generate a growing number of research papers in the specialized literature. More than 85 papers have been published so far using PIRATA data during the last ten years. In Brazil, the PIRATA project has galvanized the interest of an expanding community of researchers and has contributed to increase the support from funding agencies. The uses of PIRATA data time series have also been instrumental in the country for both: ocean and coupled ocean-atmosphere model validation studies, and real time monitoring of Tropical Atlantic oceanic conditions relevant for seasonal climate predictions over Brazil. This talk also presents the Brazilian efforts to developing its global climate model, for which both physical and biogeochemical measurements done at the PIRATA array and during the oceanographic cruises are vital.

The dominant modes of coupled ocean-atmosphere variability of the Tropical Atlantic are investigated using observational data, focusing on the cold tongue mode. The seasonal evolution and interannual variability of each mode is obtained from a joint EOF analysis of the three elements of the Bjerknes feedback, using wind speed in the western basin, and sea surface temperature (SST) and depth of the 20C isotherm from the easternmost Tropical Atlantic. Results agree with previous studies, confirming the robustness and seasonality of the positive Bjerknes feedback. The analysis reveals a dominant mode of variability remotely forced by El Nino–Southern Oscillation (ENSO) after 0–12 months, with smaller amplitude due to a limited feedback between SST and the wind speed. The second mode represents the local ocean–atmosphere interaction of the Tropical Atlantic basin, and is characterized by a strong positive feedback and a larger amplitude. Both modes are stronger during boreal summer.