Publicações

Este trabalho teve como objetivo apresentar medidas de óxido nitroso (N2O) emitido em cultura de soja (Glycine max) com a utilização da bactéria Rizobium, a qual que tem o objetivo de fixar o nitrogênio da atmosfera para a planta, evitando que seja necessária a adubação nitrogenada. A técnica utilizada para o cultivo da soja foi à convencional. Essa leguminosa foi adotada para o experimento porque apresenta a propriedade de fixar o nitrogênio do ar através de bactérias que desenvolvem nódulos radiculares nas raízes e nutre a planta, processo conhecido como nitrificação. A importância do N2O deve-se à sua relação direta com o efeito estufa global e com a destruição do ozônio estratosférico. Entre as fontes antropogênicas tem-se o crescente aumento da emissão de N2O ocasionado pelas nitrogenação do solo em atividades agrícolas. O experimento foi realizado no Departamento de Ciências Agrárias da Universidade de Taubaté (UNITAU) (23o01 S e 45o30 W) no período de 06/10/2009 à 22/04/2010 com um total de 10 campanhas de campo. Para determinar o fluxo do N2O foram usadas câmaras de acrílico transparente cobrindo 0,25m² de área, em plantas escolhidas aleatoriamente. No experimento foram utilizadas seringas de poliuretano (60 mL) adaptadas com válvula de segurança, que impediram trocas gasosas entre o meio externo e o interno das seringas. A coleta das amostras foi realizada em intervalos de 1, 10, 20, 30 e 40 minutos a partir da vedação da câmara. O óxido nitroso acumulado nas câmaras foi determinado usando-se a técnica de cromatografia gasosa, com utilização de um cromatógrafo Shimadzu GC14A equipado com detector de captura de elétrons (63Ni). A variação do fluxo obtida em todas as campanhas foi de -100,45 a 172,35 μgN2O m-2 h-1 e um fluxo médio de 11,4 μgN2O m-2 h-1. Durante o experimento foi realizado uma campanha noturna, e pode se observar que durante a noite houve uma absorção de N20 pela planta com o fluxo variando de -67,07 a 34,89 μg (N2O) m-2 h-1, apresentando uma média de -12,23 μgN2O m-2 h-1. Durante as campanhas foram observadas grandes variações no fluxo devido a altas precipitações nos meses de verão, uma vez que a emissão de N2O para a atmosfera está diretamente relacionada à saturação de umidade do solo. Os fluxos foram integrados durante todo o período de cultivo, resultando em uma emissão líquida de N2O de 2288,53 μgN2O m-². Portanto a soja durante o período diurno comportou-se como uma fonte emissora de N20 para a atmosfera. Os fluxos aqui apresentados estão dentro da faixa de valores obtidos por outros pesquisadores a partir de estudos em diferentes culturas e fertilizações. Essas estimativas ainda conservam grande incerteza, resultante das variações extremas de temperatura e níveis pluviométricos durante o cultivo da soja, porém indicam que o cultivo de soja utilizando o método convencional apresenta grande potencial para a emissão de N2O para a atmosfera.

The interaction between the Earths atmosphere and the terrestrial biosphere plays a fundamental role in the climate system and in biogeochemical and hydrological cycles, through the exchange of energy and mass (for example, water and carbon), between the vegetation and the atmospheric boundary layer, and the main focus of many environmental studies is to quantify this exchange over several terrestrial biomes. Over natural surfaces like the tropical forests, factors like spatial variations in topography or in the vegetation cover can significantly affect the air flow and pose big challenges for the monitoring of the regional carbon budget of terrestrial biomes. It is hardly possible to understand the air flow and reduce the uncertainties of flux measurements in complex terrains like tropical forests without an approach that recognizes the complexity of the spatial variability of the environmental variables. With this motivation, a partnership involving Microsoft Research, Johns Hopkins University, University of São Paulo and Instituto Nacional de Pesquisas Espaciais (INPE, the Brazilian national institute for space research) has been developing research activities to test the use of prototypes of environmental sensors (geosensors) in the Atlantic coastal and in the Amazonian rain forests in Brazil, forming sensor networks with high spatial and temporal resolution, and to develop software tools for data quality control and integration. The main premise is that the geosensors should have relatively low cost, what enables the formation of monitoring networks with a large number of sensors spatially distributed. A pilot study deployed 200+ sensors over the Atlantic coastal forest in Sao Paulo state, Brazil. Here we present the results from this study, highlighting the current discussions on applications of this type of measurements in studies of biosphere-atmosphere interaction in the tropics. Envisioning a possible wide deployment of geosensors in Amazonia in the future, the team is currently working on three main components: 1) assembly and calibration of prototypes of geosensors of air temperature and humidity, with reproductive and reliable ceramic sensor elements that will adequately operate under the environmental conditions observed in the tropics; 2) development of software tools for management, quality control, visualization and integration of data collected in geosensor networks; and 3) planning of the Amazon experimental campaign, with the installation of the first tens to hundreds of sensors within and above the rainforest canopy, aiming at a test of the system to study the spatial variability of temperature and humidity.

An increase of geo-spatial data availability due to recent technological advances in data acquisition instruments (GPS, Sensor Networks, Remote Sensing Satellites), has brought Geo-Information Science researchers to the following scenario: a huge amount of data to carry out their research as opposed to a lack of tools to handle it adequately. Thus, the demand for the inclusion of better tools for handling temporal and behavioral dimensions in relation to software such as Geographical Information Systems has increased. Nevertheless, the current GIS, referred to as 20th Century GIS, were not designed in order to meet such a demand. Therefore, the need has come up to design a new GIS generation, the 21st Century GIS, with tools capable of addressing researchers needs. This work aims at proposing the development of software architecture to support a data-intensive Geographical Information Science as part of an effort to establish a 21st Century Geographical Information Engineering.

Algoritmos de segmentação e classificação detectam feições presentes em imagens, produzindo conjuntos de dados vetoriais compostos por polígonos. Um processo de generalização é necessário para gerar mapas com diferentes graus de detalhe em diferentes escalas e reduzir o armazenamento de dados. Este artigo tem o objetivo de revisar e sugerir melhorias em métodos de generalização de polígonos, quando aplicado a estes conjuntos de dados vetoriais, buscando manter a topologia original e minimizar a discrepância de área do mapa de saída. O conjunto de dados usado é parte do mapa de desflorestamento da região Amazônica, medido pelo PRODES. Os resultados mostram que a eficiência da generalização pode ser melhorada e a discrepância de área também pode ser reduzida.

This communication evaluates the mechanisms associated with the inherent difficulty of global coupled ocean-atmosphere models to simulate the thermal vertical structure of the equatorial Atlantic. The study is done with use of the coupled GCM developed at CPTEC, which consists of CPTECs global atmosphere model fully coupled over the global tropics (40S-40N) with GFDLs MOM3 ocean GCM. Coupled and uncoupled simulations were calculated in ensemble mode, with ten members runs, 8 months long each starting at every calendar month for the period 1982-2001. Systematic differences between simulations done with the CGCM and OGCM forced with prescribed atmospheric fluxes, as well as against PIRATA array data over the tropical Atlantic are used to argue that the systematic errors of the coupled model over the equatorial Atlantic can be separable into a surface and under-thermocline ones. Evidences are shown to suggest that surface temperature systematic errors are attributable to insufficiencies on AGCM stratus parameterization, which generated excess solar radiation over the regions of stratus decks over cold waters along the southwestern coast of Africa. For the under-thermocline processes, however, it is shown a remarkable locking to the seasonal cycle, with systematic errors maximum amplitude occurring in April/May, regardless of the month of model initialization. Linkages to AGCM rainfall deficiencies over the equatorial landmasses are speculated.

Carbon Monoxide (CO) is emitted to the atmosphere over the Amazon by biomass combustion as well as being formed by oxidation of hydrocarbons. Carbon dioxide (CO2) is emitted by combustion and respiration and absorbed by photosynthesis. CO and CO2 mixing ratios were measured continuously at Maxaranguape, a coastal site, and Tapajos km67, an inland site, during the BARCA (Balanço Atmosférico Regional de Carbono na Amazônia) campaign. We report here results from November 2008 through May 2009 including both the two intensive flight campaigns, BARCA-A in November-December 2008 and BARCA-B in May 2009 and the period between. The Maxaranguape coastal station is located on a bluff overlooking the Atlantic Ocean about 40 km north of Natal. Steady easterly trade winds deliver tropical marine air to the site most of the time except for occasional periods of nighttime land breezes. The Tapajos km67 site is located in the Tapajos National Forest about 60 km south of Santarem. Trajectory analysis indicates that coastal air off northeast Brazil contributes to the easterly flow entering the Amazon basin. Mixing ratio gradients between this pair of sites is an overall indicator of the net influence of sources in the eastern Amazon basin. During the dry season CO concentrations at km67 exceed the mixing ration in marine air by 100 – 200 ppb, indicating the influence of biomass burning across the region. CO mixing ratios at km67 during the wet season are on average 40 ppb higher than at Maxaranguape, which we interpret as CO production from biogenic hydrocarbons, though there may also be some influence from urban areas in eastern Amazon and along the coast. Throughout the wet season in 2009 leading up to the BARCA-B flights in May, CO2 at km67 was elevated by 15-25 ppm relative to CO2 in the marine-air inflow sampled at Maxaranguape, suggesting a net efflux of CO2 during this entire period and consistent with the analysis of airborne observations.

In Central Brazil every year large areas of forest, cerrado and pasture land are burned emitting primary carbonaceous aerosols into the atmosphere. These interfere with the radiative budget, affecting directly the amount of solar radiation that is reflected and scattered back to space, and partly absorbed by the atmosphere. The long wave terrestrial radiation is also affected. Aerosols also affect cloud microphysics acting as cloud condensation nuclei (CCN), modifying the precipitation pattern and the cloud albedo. During the South American burning season, aersosols have a significant impact on local and regional air quality affecting visibility and human health by particle inhalation causing pulmonary diseases. The recognition of atmospheric aerosols importance led to the necessity of quantifying and optimizing its sources, distributions and sinks in the troposphere to improve simulations with atmospheric chemical models. An improvement of the aerosol representation in such models can be achieved through data assimilation methods including available aerosol observations. In this study an assimilation system was used based on the three dimensional variational data assimilation method (3D-VAR) using the Coupled Chemical-Aerosol-Tracer Transport – Brazilian Regional Modeling System (CCATT-BRAMS). The assimilated observations are mass concentration (MC) of particular matter smaller than 2.5 µm (PM2.5). The observations were collected in October 2007, during the Cloud-Aerosol Interaction Measurements (CLAIM) campaign, which took place in the region of the city Alta Floresta in the state of Mato Grosso, Brazil. The measurements of PM2.5 were collected by a DATARAM instrument aboard the aircraft that collected information with 10s or 30s frequency. During the campaign 17 flights were carried out, 13 of which could be used in this study. In this paper we present the data and its assimilation results, evaluate its improvement of the model simulation and discuss its general impact on the chemical state of atmosphere.