Padrões de temperatura superficial da Lagoa dos Patos, Brasil, utilizando dados NOAA-AVHRR : uma análise de ciclo anual

A processing chain for NOAA-AVHRR data can be used to retrieve lake surface water temperatures (LSWT) measurements based on a nonlinear sea surface temperature (NLSST) algorithm generally applied to open ocean conditions. This extended application has been widely used in lakes around the world and the bias of the algorithm is around 1-1.5°C. LSWT monthly average maps of surface temperature have been generated for Lagoa dos Patos, at Rio Grande do Sul State, covering the period from August/2007 to July/2008, for daytime and nighttime in order to study the annual cycle. Results show strong lake surface temperature variations within that period, and reveal an interaction with the adjacent ocean in the estuarine region. Temperatures ranged between 9.9 to 29.5 °C in daytime and from 9.9 to 27.8 ºC in nighttime. It was found that the bathymetric profile is the most significant parameter influencing LSWT salient features and the thermal dynamic of the lagoon. Knowledge of these variations gives new insights of local processes, and leads to possibilities for modeling local scale phenomena involved. The analysis procedure also provides a more realistic depiction of the distribution of the temperature than climatological maps.Rotinas de processamento em dados NOAA-AVHRR podem ser empregadas para estimar a temperatura superficial de lago (TSL) com base em algoritmos tradicionalmente desenvolvidos e aplicados em ambientes oceânicos. Esta extenção da aplicação tem sido largamente utilizada em diversos lagos ao redor do mundo alcançando um bias entre 1-1,5 °C resultante do algoritmo. Mapas mensais de temperatura da superfície da Lagoa dos Patos, RS, cobrindo o período de Agosto/2007 a Julho/2008 foram gerados para período diurno e noturno com o intuito de estudar o ciclo anual. Os resultados mostram grandes variações de temperatura dentro desse período, e revelam a interação existente com o Oceano Atlântico na região estuarina. As temperaturas variam entre 9,9 a 29,5 ºC durante o dia e entre 9,9 a 27,8 °C durante a noite. Foi verificado que o perfil batimétrico é o parâmetro mais significante influenciando as feições de TSL e a dinâmica termal da lagoa. O conhecimento dessas variações produz novas percepções sobre os processos locais, e conduz a diferentes formas de modelagem dos fenômenos envolvidos em escala local. A análise fornece também uma descrição mais realística sobre a distribuição superficial da temperatura do que mapas climatológicos

The XDSPRES CL-based package for reducing OSIRIS cross-dispersed spectra

We present a description of the CL-based package XDSPRES, which aims at being a complete reducing facility for cross-dispersed spectra taken with the Ohio State Infrared Imager/Spectrometer, as installed at the SOAR telescope. This instrument provides spectra in the range between 1.2um and 2.35um in a single exposure, with resolving power of R ~ 1200. XDSPRES consists of two tasks, namely xdflat and doosiris. The former is a completely automated code for preparing normalized flat field images from raw flat field exposures. Doosiris was designed to be a complete reduction pipeline, requiring a minimum of user interaction. General steps towards a fully reduced spectrum are explained, as well as the approach adopted by our code. The software is available to the community through the web site http://www.if.ufrgs.br/~ruschel/software.Comment: 14 pages, 10 figure

Impact assessment of agrarian reform, by stability indicator and tendency index of changes in land use and cover

A detecção de mudanças no uso e na cobertura da terra é uma aplicação do sensoriamento remoto que utiliza a dimensão temporal para analisar imagens, buscando a identificação das alterações nas respostas espectrais dos pixels homólogos, pela aplicação de limiares que distingam as regiões que sofreram alguma alteração. A análise ponto a ponto permite inferir sobre a quantidade e qualidade das mudanças detectadas, já a análise de resultados comparativos, sobre uma série temporal de imagens permite avaliar a dinâmica das alterações, nos sentidos da topologia e intensidade, permitindo avaliar taxas de mudança e a espacialização de suas ocorrências. Várias técnicas estão disponíveis para detectar alterações no uso e cobertura da terra, a partir de imagens coletadas por sensores orbitais. Dois grupos principais se destacam: técnicas de pré-classificação, e técnicas de pós-classificação, diferindo basicamente na aplicação de limiares que definem mudanças. Este trabalho usa técnicas de detecção baseadas em subtração de imagens em pós-classificação com Máxima Verossimilhança. O objetivo é estimar a sensibilidade e a adequação destas técnicas para a detecção e análise de mudanças na cobertura e uso da terra, em dois períodos de comparação: de 1988 a 2001, e de 2001 a 2006. Além disto, todo o período de 18 anos é estudado. A área de estudo é a região da Campanha, no Estado do Rio Grande do Sul, Brasil, zona predominantemente rural e que sofreu acentuadas mudanças durante o período estudado, especialmente por reforma agrária. Os resultados permitiram a comparação dos dois tratamentos e verificar a acurácia das detecções. As principais dificuldades foram os ciclos fenológicos, as florestas artificiais de ciclo longo, e as áreas cobertas por nuvens. Não foi possível definir claramente a melhor técnica; esta definição depende dos objetivos específicos, da escala e natureza da região de estudo, e das classes de mudanças analisadas, além da qualidade das imagens disponíveis.The detection of alterations in land use and cover is an operation in Remote Sensing which adds a time dimension to the analysis of information in images. This is done when images are compared, by groups of two, at certain space and time, looking for spectral responses stored in pairs ofhomologous pixels, through the application of thresholds which lead to the differentiation between change and non-change. A point-to-point, or instant-to-instant analysis, permits to infer on the amount and quality of alterations detected in a region, during a certain period. The comparative analysis between two or more of these results, via a time series of images, informs on the dynamics of transfotmations in other aspects, as topology, intensity, kind of change (substitution or conversion), and change rate. Several techniques are available to detect alterations in land use and cover, from digital images collected by orbital sensors. Two larger groups can be highlighted: pre-classification techniques, and post-classification techniques. They differ basically on over which products the thresholds defining changes are applied, these products being either thematic ones for image classification, or the image itself. This work uses detection techniques based on image subtraction in post-classification with the Maximum Likelihood. The objective is to estimate the sensitivity and adequacy of these techniques for the detection and analysis of changes in land use and cover during two comparison periods: the first one is from 1988 to 2001; the second, from 2001 to 2006. Besides, the whole 18-years period is studied to detect tendencies of the transformation of the region. The study area is at the Campanha Sul region, at Rio Grande do Sul State, Brazil. It is largely rural, heterogeneous and dynamic, since during the period covered (1988-2006), large estates where either converted into smaller properties, family-managed, through an intensive policy of agrarian reform (from the mid-eighties to the midnineties), or, more recently, by industrial-style cultures of forests to serve the paper industry. The results allowed comparing the different treatments and to verifY the accuracy of detections. The main difficulties were the phenological cycles, the various phases of long-cycle artificial forests, and cloud-covered areas. It was not possible to clearly define the better or more accurate technique; this definition depends of specific objectives, of the scale and nature of the study region, and of the classes of change being analyzed, besides of the quality of available images

Near-infrared surface photometry of early-type galaxies

CCD infrared (JHKs) photometry was performed on a sample of 10 elliptical and 2 lenticular galaxies. Isophotal parameters, brightness profiles, integrated colors and color gradients arepresented. Color gradients found arevery weak, showing bluer colors towards the outer regions. The colors of the sample galaxies are compatible with stellar populations like those found in metal-rich clusters of the Galaxy; objects NGC7192, NGC7562 and NGC7619 are compatible with less metal-rich populations. The brightness profile of most galaxies is well described by the r1/4 law. The profiles of NGC1600 and NGC720 are described by Sérsic’s law with n ∼ 1.5 andn ∼ 1.8 respectively. The infrared effective radius of the objects studied is typically one half of its counterpart in the B band, which can be an indication that the stellar population that dominates the infrared emission is more concentrated in the central regions. Weshow that the sample satisfies the Fundamental Plane relation of elliptical galaxies in the infrared, with an rms scatter of 0.20 for J and H and 0.23 for Ks

Posicionamento em Imagens Digitais do Sistema Goes

Este trabalho mostra como se pode transformar coordenadas geodésicas (latitude, longitude), de pontos previamente escolhidos, em coordenadas retangulares (linha, coluna) de uma imagem digital do satélite meteorológico GOES-7 por meio de transformações polinominal ou projetiva. O objetivo principal dessa transformação é permitir a localização de sítios potenciais para investigar o grau de nebulosidade existente numa região com vistas à instalação de observatórios astronômicos. É investigada a eficiência da transformação polinominal e projetiva para esse tipo de imagem as quais, parecem resolver o problema com acurácia

Detection of grapevine leaf stripe disease symptoms by hyperspectral sensor

Hyperspectral sensors can measure reflectance in a wide range of the electromagnetic spectrum. These can be used as an indirect method for detecting plant disease, by comparing the specific spectral signatures between symptomatic and asymptomatic vegetation. Grapevine Leaf Stripe Disease (GLSD), including the Esca complex, is a very important Grapevine Trunk Disease (GTD) worldwide. With the objective of developing an innovative method for quantitative and qualitative analyses of symptomatic plants using remote sensing, this study measured and characterized the spectral behaviour of GLSD asymptomatic and symptomatic grapevine leaves using a hyperspectral sensor. Asymptomatic, initial and final GLSD symptomatic leaves were collected in two stages of the phenological cycle (before and after harvest) from a ‘Merlot’ vineyard in Veranópolis, Rio Grande do Sul, Brazil. Reflectance measurements (350 to 2,500 nm) were performed using a spectroradiometer. The spectral behaviour of vine leaves with GLSD symptoms changed especially in the visible light range; reflectance increased in the green edge (520-550 nm) and red edge (700 nm) associated with reduced photosynthetic pigments (especially chlorophyll b). At near-infrared, reflectance decreased, especially in leaves with advanced GLSD, due to cell structure loss and toxin accumulation induced by pathogens. Even at different intensities, leaf reflectance changed in initial and final GLSD symptoms and at different stages of the cycle. These results showed that proximal, non-destructive sensing techniques may be useful tools for detecting the changing spectral behaviour of grapevine leaves with GLSD, which could be used for disease identification and detection

Macrozoneamento do Estado do Rio Grande do Sul

Earth imaging technologies using orbital platforms have allowed new approaches in the analyses, compartmentalization, and territorial visualization. These cartographic informations have many applications in agricultural, urban and environmental monitoring. In the case of vast geographic regions, such as Brazil, one expects that the many products obtained from imaging technology will be used to reduce costs and to provide a better understanding of the territory. The crossanalysis of the products from various imaging systems of different characteristics (e.g. pixel size, band, and data) allows the improvement of current maps as well as more complex analyses. The macrozoning of the state Rio Grande do Sul was accomplished by integrating orbital data of different characteristics and other cartographic products. The following sources supplied data on Rio Grande do Sul: 1) Landsat TM mosaic; 2) temporal NDVI/NOAA combination; 3) geomorphologic map; and 4) altimetric map. The cross-analysis of the data allow us to gather in a single map information from distinct cartographic sources, which better represent the diversity of the thematic classes in relation to the usage patterns of soil and plant life in the state of Rio Grande do Sul.Earth imaging technologies using orbital platforms have allowed new approaches in the analyses, compartmentalization, and territorial visualization. These cartographic informations have many applications in agricultural, urban and environmental monitoring. In the case of vast geographic regions, such as Brazil, one expects that the many products obtained from imaging technology will be used to reduce costs and to provide a better understanding of the territory. The crossanalysis of the products from various imaging systems of different characteristics (e.g. pixel size, band, and data) allows the improvement of current maps as well as more complex analyses. The macrozoning of the state Rio Grande do Sul was accomplished by integrating orbital data of different characteristics and other cartographic products. The following sources supplied data on Rio Grande do Sul: 1) Landsat TM mosaic; 2) temporal NDVI/NOAA combination; 3) geomorphologic map; and 4) altimetric map. The cross-analysis of the data allow us to gather in a single map information from distinct cartographic sources, which better represent the diversity of the thematic classes in relation to the usage patterns of soil and plant life in the state of Rio Grande do Sul

Espectroradiometria de espéçies vegetais e correlação com classificação sobre imagens Landsat-TM

Espectroradiometric data was colleted on samples (branches, leaves)of araucaria angustifolia, eucalyptus sp. and pinus elliottii. An IRIS GER Mark V radiometer was used. Mean spectra are derived in wavelengths corresponding to Landsat TM bands, and compared with the spectral responses of these plants, observed in Landsat images of the North-East of Rio Grande do Sul State, Brazil. Results indicate that vegetal classification from Landsat images is supported by laboratory measurements.Pages: 1391-139