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Changes in land surface properties, often associated with changing vegetation and soil characteristics, have dramatic effects on the climate simulated by general circulation models (GCMs). Thus, during the last several years efforts are aimed to evaluating land surface parameterizations. Currently, there is a diversity of soil-vegetation-atmosphere schemes. The objectives of these models are mainly in the improvement of bottom boundary condition of the atmospheric models by accurately evaluating the ground-surface impact on the atmosphere. The surface schemes ranges from those that simulate only the exchange of momentum, energy and water vapor between vegetated surface and atmosphere, as the “Simplified Simple Biosphere Model” SSiB, even more sophisticated models, as, for example, the “Integrated Biosphere Simulator Model” IBIS, which includes, in addition to processes listed above, the terrestrial carbon and nutrient cycling, and vegetation dynamics. The SSiB is coupled to the global and regional meteorological models of the Brazilian Center for Weather Forecasting and Climate Studies/Brazilian National Institute for Space Research (CPTEC/INPE). It includes a complex treatment of the albedo, the energy balance of the surface and the soil moisture. Recently, the IBIS-2.6 model of dynamical vegetation was also coupled to the GCM/CPTEC to make it able to diagnose the loss of biomass and its impact on storage of energy and water. To test the surface modelxs performance, different simulations are been proposed. The goal of this work is evaluating the energy balance simulated by SSiB and IBIS models against two sets of measurements. The data were collected at a tropical rainforest in the Brazilian Amazon and in the caatinga in Northeast Brazil. The dataset for Amazonian forest used in this work was collected at the Reserva Biológica do Jaru (62º22’W; 10º45’S) forest site, located in the state of Rondônia, Brazil. Micrometeorological and hydrological data were collected during 2001, as part of the Large-Scale Biosphere-Atmosphere Experiment in Amazonia LBA. The caatinga is a type of vegetation adapted to the semi-arid conditions, with varied physiognomy, and covers the northeast portion of Brazil. It occupies an extension of about 800,000 km2 that corresponds to 70% of the region. Micrometeorological and hydrological data were collected from July 2004 to June 2005, in a site located in the Agricultural Research Center of the Semi-Arid Tropic CPATSA (9°03′ S; 40°19′ W; 350 m, Petrolina, Pernambuco, Brazil. In this study, the surface schemes were used in the so-called off-line mode. In this version, the models were not coupled with the atmospheric model and were driven using prescribed atmospheric forcing. The results of the energy balance simulated by both models and for each vegetation type were compared. The results showed that the net radiation was well simulated by SSiB model for both caatinga and forest sites, while the latent heat fluxes were overestimated for both sites. In contrast, the sensible heat flux was underestimated for forest and overestimated for caatinga, mainly during the night period; notwithstanding, the values for forest were nearer to the observed ones. With the IBIS model, the simulations for the radiation balance were close to the observed data for forest site, in contrast to the obtained for caatinga site. The latent heat flux and the sensible heat flux were underestimated by the model for caatinga. For forest site, the energy partition was not well simulated; thus, the SSiB model provides better results. It is highlighted that the simulations with the IBIS model were made considering the parameters previously calibrated for both forest and caatinga. Thus, these results are preliminary and other analyses are still necessary to better understand the biophysical processes involved. ion balance were close to the observed data for forest site, in contrast to the obtained for caatinga site. The latent heat flux and the sensible heat flux were underestimated by the model for caatinga. For forest site, the energy partition was not well simulated; thus, the SSiB model provides better results. It is highlighted that the simulations with the IBIS model were made considering the parameters previously calibrated for both forest and caatinga. Thus, these results are preliminary and other analyses are still necessary to better understand the biophysical processes involved.

Modelos espacialmente explícitos são simulações computacionais que descrevem algum fenômeno que tem uma ocorrência bem definida no espaço e no tempo. Desse modo, o desflorestamento é um fenômeno espaço temporal. Ele ocorre em uma determinada localização no espaço e no tempo. Então, é possível fazer modelos que buscam entender este fenômeno com relação a estas duas variáveis. Por exemplo, aproximação a infra-estruturas afeta o desflorestamento? Ou um incentivo de algum programa político que ocorre em um determinado período do tempo? Este trabalho descreve alguns elementos básicos para construir modelos espacialmente explícitos.

The Amazon forest plays an important and complex role in the global water and carbon cycle, and important advances have been made in understanding the underlying processes in recent years. However, reconciling modeled mechanisms with observations across scales remains a challenge. To better address this challenge, we initiated a Model Intercomparison Project for the Large-Scale Biosphere Atmosphere Experiment in Amazonia (LBA-MIP) to integrate modeling and observational studies for improved understanding of Amazon basin water and carbon cycling. Here, we report on further analysis from this project, which uses a network of meteorological observational sites (the BrasilFlux network) in forest and converted lands to drive a suite of land surface ecosystem models that simulate energy, water and CO2 fluxes. We focus here on controls on gross primary photosynthesis (GPP) and evapotranspiration (ET), and in particular on how well models capture the observed diurnal and seasonal cycles across sites. Light, moisture, and phenological controls on GPP and ET were intercompared across models and observations. Available energy as the dominant control on ET across the Amazon basin is best reproduced by those models with high moisture storage capacity, but models were able to accomplish this via different ecohydrological mechanisms. Further, some models which capture observed seasonal cycles in ET predict unrealistic patterns of leaf area index (LAI) and/or overestimate photosynthesis and light use efficiency (LUE). Modeled photosynthesis by many models also remains oversensitive to short-term drought in evergreen seasonally dry forests. This analysis highlights the need to incorporate more realistic soil-root-leaf continuum hydraulics in models and invest in ancillary measurements at flux tower sites (e.g., deep soil moisture profiles, LAI, and litterfall) designed to aid empirical discrimination among different model mechanisms used to match observed seasonal patterns.

Based on studies of the United Nations Population Fund (UNPA), 82% of South America populations live in urban areas as of 2007, with a rate of growth about 1,7% a year. In Brazil, 70% of the population lives in the area originally covered by the Atlantic Forest (Mata Atlântica). The urban sprawl has been degrading the original ecosystem, and the current impact on the environment will not be easily reversed. Therefore, the goal of this paper is to analysize the changes in precipitation patterns over the past 5 decades and their possible associations to the gradient of urbanization in Eastern of São Paulo State, Brazil. We used precipitation time series of from Agência Nacional das Águas (ANA) and NOAA Analysis (National Oceanic and Atmospheric Administration), and satellite images from LANDSAT. The low frequency effects are filtered in the rainfall time series. The data was grouped in 10-year subsets and then, the annual distribution was analyzed comparing each decade in order to evaluate the changes in precipitation over the last 50 years. The results show a change in the annual distribution along the time.

Brazil is one of the largest producers of sugarcane and the Sao Paulo State is currently responsible for 60% of the national production. Areas previously used for livestock and citrus production have been gradually substituted by sugarcane due, mainly, to the current Brazilian government incentive for the sugarcane ethanol fuel production. The usual pre-harvest sugarcane burning in Brazil emits a significant amount of aerosols to the atmosphere. The land use/cover change and the presence of aerosols in the atmosphere have the potential to affect the local energy budget and therefore the rainfall pattern in the region. In this work we analyze the changes in precipitation patterns over the past 5 decades and their possible associations with these new land use scenario in São Paulo State, Brazil. We used precipitation time series from the network rainfall data of the Brazilian National Water Agency (Agência Nacional das Águas – ANA) and the National Oceanic and Atmospheric Administration (NOAA), a gridded data composed with multi sources information, with 1 degree of resolution. Statistical techniques (Lanczos filter) were used to filter the low frequency oscillation in the rainfall time series and the data was grouped in 10-year subsets. The annual distribution was analyzed comparing each decade in order to assess the changes in the precipitation pattern over the last 50 years in the most important area of sugarcane plantation. Preliminary results indicate a change in the annual distribution along this time period and possible association with sugarcane production expansion is under investigation.

The Brazil-Malvinas Confluence (BMC) region in the South Atlantic Ocean is characterized by the thermal gradients of the meeting between the warm Brazil Current (BC) and the cold Malvinas Current (MC). The region is considered a key region for understanding the linkage between Antarctica and South America. This paper aims to describe the atmospheric wind modulation forced by the thermal contrasts of the BMC region. Winds were available from the QuikScat satellite and NCEP/NCAR reanalysis. Sea surface temperature (SST) was derived from the AMSR sensor onboard the Aqua satellite. Analysis of the satellite data demonstrated that wind intensity fields were directly related to the SST fields attesting the coupling between the ocean and the atmosphere at the BMC region. The satellite data confirms former evidence (Pezzi et al., 2005, 2009; Acevedo et al., 2010) that wind intensity increases over the warm waters of BC and decreases over the cold waters of the MC. The reanalysis data was not as able as the satellite data to represent the atmospheric modulation in terms of wind intensity. This work suggests that the use of satellite data is important when studying ocean-atmosphere coupling over regions of intense oceanic mesoscale activity.

This paper presents a compilation of the main results obtained by this research group in twenty years of field research on forest clearing fires in the Brazilian Amazon region. Experiments were conducted in Manaus (state of Amazonas) (2 experiments), Tomé-Açu (state of Pará) (1 experiment), and Alta Floresta (state of Mato Grosso) (8 experiments). The research congregated 6 Brazilian and 2 American research institutions. Results on the following main themes of the research are presented: – Biomass consumption and emission rates of CO2 under fire; – Emission factors of combustion gases produced in the burns; – Log smoldering; – Under-story fire propagation; – Charcoal formation; – Changes of composition of the water percolated through the soil; – Mercury emissions by fires. The paper also discusses the newly approved thematic project that will support research for the following 4 years. Experiments will be conducted in Cruzeiro do Sul and Rio Branco (state of Acre) and again in Alta Floresta.