Rita de Cássia Marques Alves

Avaliação de fluxos de calor e evapotranspiração pelo modelo SEBAL com uso de dados do sensor ASTER

The objective of this study was to evaluate the efficiency of SEBAL model in estimating soil surface energy fluxes and daily evapotranspiration for a large area of irrigated rice farms, near the municipality of Paraiso do Sul, RS, Brazil, using data from ASTER sensor. The evaluated variables are important weather and climatic parameters for agrometeorological studies and rationalization of water use. The conventional methodologies for estimating these parameters generally present uncertainties, which increase when concern is in the spatial behavior of such parameters. The Surface Energy Balance Algorithm for Land (SEBAL) was applied in an Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) scene and the estimates were compared to micrometeorological data retrieved from a station located in the studied area. The most accurate modeled parameter estimatives were sensitive heat and evapotranspiration, and the one which presented the highest error was soil heat flux. The adopted methodology was able to reproduce surface energy fluxes for agrometeorological and crop yield studies.

ESTIMATIVA DE ÁREA CULTIVADA COM ARROZ IRRIGADO PARA O ESTADO DO RIO GRANDE DO SUL A PARTIR DE IMAGENS MODIS

Este trabalho teve como objetivo testar uma metodologia de baixo custo e facil implantacao, utilizando imagens MODIS, para definir as areas cultivadas com arroz irrigado no Rio Grande do Sul (RS) e monitorar o cultivo ao longo do ciclo para dez safras agricolas. O estudo foi realizado abrangendo as seis regioes orizicolas do Estado do RS. Foram utilizados dados oficiais de area cultivada com arroz irrigado e imagens NormalizedDifferenceVegetation Index/ ModerateResolutionImagingSpectroradiometer (NDVI/MODIS) referentes as safras agricolas de 2000/01 ate 2009/10. A metodologia testada baseou-se no comportamento espectro-temporal da cultura do arroz irrigado. As maiores diferencas entre os valores de area estimados e os oficiais, em nivel regional, foram de -11,5% na Planicie Interna e 5% na Depressao Central. Os menores desvios ocorreram nas regioes da Campanha e Fronteira Oeste, sendo respectivamente de 2,2% e -3,1%. Os resultados mostram que a metodologia proposta e eficiente e pode ser usada tanto para complementar o atual sistema nacional de previsao de safras, como para o monitoramento das areas cultivadas no RS.

Estudo de aerossóis atmosféricos e aplicação de modelos numéricos

The main purpose of the present work is to study the concentration of atmospheric particles (PM10 and PM2.5) in the Candiota (RS) region using HV PM10 and dichotomous samplers. Four sampling sites at a distance of 50 km from the emission source were selected: Acegua, Aeroporto, 8 de Agosto and Pedras Altas. Samples were collected from December 2000 to December 2001. The values obtained with the ISCST (Industrial Source Complex Term) model and with the samplers were compared on January 21st, April 5th, July 14th, August 1st, and October 13th 2001, and are representative of frontal systems occurring in the study area.

Aerosols concentration in the Candiota area applying different gravimetric methods of sampling and numeric modelling

The main purpose of the present work is to study the concentration of atmospheric particles in the Candiota region, in the state of Rio Grande do Sul, where the Presidente Médici coal power plant is located. Aerosol samples were collected at the studied locations between December 2000 and December 2001 during 24 h periods at 15 day intervals using HV PM10 and dichotomous samplers. Then, the values obtained with the ISCST (Industrial Source Complex Term) model, with the HV PM10 sampler at all studied stations, and with the dichotomous sampler at the 8 de Agosto station were compared with each other. The results show that the values for the model had been underestimated in relation to the HV PM10 data for the studied stations, but agreed with the values obtained with the dichotomous sampler.

Modelo agrometeorológico-espectral para estimativa da produtividade de grãos de arroz irrigado no Rio Grande do Sul

The objective of this study was to estimate the irrigated rice grain yield through the adjustment of the agrometeorological-spectral model in the State of Rio Grande do Sul, Brazil. For the six rice-growing regions of the State, the data on irrigated rice grain yield and crop area, meteorological data and the Normalized Difference of Vegetation Index (NDVI) images of moderate resolution imaging spectroradiometer (MODIS) sensor were used from August to April, for the 2000/2001 to 2009/2010 crop seasons. The minimum air temperature and NDVI are associated to the irrigated rice grain yield in several crop development periods. The agrometeorological-spectral model to estimate irrigated rice grain yield, adjusted through the oriented approach by the climate-plant relationship, is adequate for the estimates at regional levels. This could predict the estimates one month before the end of the harvest.

Morfologia e química de cinzas do vulcão Puyehue depositadas na região metropolitana de Porto Alegre em junho de 2011

The National Geological Survey of Chile reported a volcanic explosion of order 5 in the Los Rios area (Volcanic Complex in Puyehue - Cordon Caulle) on June, 2011. This complex comprises Pleistocene volcanoes built in six large evolutionary phases and preserves 131 km³ of the vulcanites. The Puyehue stratovolcano (69 ky) had its last records of the explosive and effusive activity in 1921, 1922, and 1960. The explosion on June, 2011 generated a tephra and gas column of 10 km high under high-temperature conditions. The surrounding air was heated and incorporated reducing the density of the the column, which rises into the atmosphere. The pyroclastic material stops in a balance zone between the densities of the medium and head of the plume, and the wind action determines the dispersion of the ashes. On June 9, 10 and 14, 2011, the Fundacao Estadual de Protecao Ambiental (FEPAM-RS) collected Puyehue ashes in its filters at the eighth District of the Meteorology (Porto Alegre). The concentrations remained below the Conselho Nacional do Meio Ambiente - CONAMA standards (150 mg/m³) and Guide Value (WHO-VG = 25 mg/m³). The research by using scanning electron microscope (SEM) indicated that the ashes are thin (2 - 30 microns), with elongated angular and placoid habits. The curved ends, corresponding to the boundaries between vesicles and melt, are vitreous (shards), rich in SiO2 and Al2O3, and show low alkali and FeOt contents. The diffractometer obtained in reworked tephra indicates plagioclase and cristobalite presence, and these minerals were also observed in the fall deposits studied in Argentina.

Utilização de modelagem numérica para o estudo da dispersão de poluentes emitidos pela usina termoelétrica Presidente Médici

The purpose of the present study is to evaluate the atmospheric behavior in the dispersion of the pollutants SO2, PM10 and NOx emitted by the President Medici power plant in Candiota, RS. The RAMS atmospheric model was applied and the simulations were conducted from april in 20 to 24, 2004. The concentrations of the pollutants simulated by RAMS were compared with the data measured at the air quality monitoring stations. The results showed significant influence of the emissions generated by the power plant on the concentration of the pollutants.

Estimating Eddy Diffusivities Coefficients From Spectra Of Turbulence

The behaviour of spectra of turbulence in the surface layer is used to estimate the vertical eddy diffusivity coefficient in order to describe the dispersion of pollutant emitted by a thermoelectric power plant located in the south of Brazil. The simulation of the transport of the material is done with an analytical solution of advection-diffusion equation. The meteorological inputs for this model were obtained in field campaigns conducted in the region. The data set analysed comprised twenty-four hours of turbulence measurements. The results of the model are compared with results obtained by the same model but using different parameterization for the eddy difiusivity coefficient.

Climate trends of air temperatures in the Rio Grande do Sul state, South Brazil

1 Parte integrante de Projeto financiado pelo CNPq

Estações meteorológicas de código aberto : um projeto de pesquisa e desenvolvimento tecnológico

This paper reports an experience of scientific research and technological development: the construction of weather stations based on free hardware and software aimed at the formation of a citizen science network for meteorological and environmental monitoring. Students from different grade levels and subject areas are participating in this research and development project. The results are related to measurements with the first prototype from the Arduino platform.