Abstract. El Niño South Oscillation (ENSO) is one climatic phenomenon related to the inter-annual variability of global meteorological patterns influencing sea surface temperature and rainfall variability. It influences human health indirectly through extreme temperature and moisture conditions that may accelerate the spread of some vector-borne viral diseases, like dengue fever (DF). This work examines the spatial distribution of association between ENSO and DF in the countries of the Americas during 1995-2004, which includes the 1997-1998 El Niño, one of the most important climatic events of 20 th century. Data regarding the South Oscillation index (SOI), indicating El Niño-La Niña activity, were obtained from Australian Bureau of Meteorology. The annual DF incidence (AI y ) by country was computed using Pan-American Health Association data. SOI and AI y values were standardised as deviations from the mean and plotted in bars-line graphics. The regression coefficient values between SOI and AI y (r SOI,AI ) were calculated and spatially interpolated by an inverse distance weighted algorithm. The results indicate that among the five years registering high number of cases (1998, 2002, 2001, 2003 and 1997), four had El Niño activity. In the southern hemisphere, the annual spatial weighted mean centre of epidemics moved southward, from 6°31' S in 1995 to 21°12' S in 1999 and the r SOI,AI values were negative in Cuba, Belize, Guyana and Costa Rica, indicating a synchrony between higher DF incidence rates and a higher El Niño activity. The r SOI,AI map allows visualisation of a graded surface with higher values of ENSO-DF associations for Mexico, Central America, northern Caribbean islands and the extreme north-northwest of South America.

Resumo -O objetivo deste trabalho foi avaliar o desempenho dos classificadores digitais SVM e K-NN para a classificação orientada a objeto em imagens Landsat-8, aplicados ao mapeamento de uso e cobertura do solo da Alta Bacia do Rio Piracicaba-Jaguari, MG. A etapa de pré-processamento contou com a conversão radiométrica e a minimização dos efeitos atmosféricos. Em seguida, foi feita a fusão das bandas multiespectrais (30 m) com a banda pancromática (15 m). Com base em composições RGB e inspeções de campo, definiramse 15 classes de uso e cobertura do solo. Para a segmentação de bordas, aplicaram-se os limiares 10 e 60 para as configurações de segmentação e união no aplicativo ENVI. A classificação foi feita usando SVM e K-NN. Ambos os classificadores apresentaram elevados valores de índice Kappa (k): 0,92 para SVM e 0,86 para K-NN, significativamente diferentes entre si a 95% de probabilidade. Uma significativa melhoria foi observada para SVM, na classificação correta de diferentes tipologias florestais. A classificação orientada a objetos é amplamente aplicada em imagens de alta resolução espacial; no entanto, os resultados obtidos no presente trabalho mostram a robustez do método também para imagens de média resolução espacial.Termos para indexação: classificação orientada a objetos, gestão territorial, sensoriamento remoto, resolução espacial, uso e cobertura do solo. Comparative analysis of digital classifiers of Landsat-8 images for thematic mapping proceduresAbstract -The objective of this work was to evaluate the performance of SVM and K-NN digital classifiers for the object-based classification on Landsat-8 images, applied to mapping of land use and land cover of Alta Bacia do Rio Piracicaba-Jaguari, in the state of Minas Gerais, Brazil. The pre-processing step consisted of using radiometric conversion and atmospheric correction. Then the multispectral bands (30 m) were merged with the panchromatic band (15 m). Based on RGP compositions and field inspection, 15 land-use and land-cover classes were defined. For edge segmentation, the bounds were set to 10 and 60 for segmentation configuring and merging in the ENVI software. Classification was done using SVM and K-NN. Both classifiers showed high values for the Kappa index (k): 0.92 for SVM and 0.86 for K-NN, significantly different from each other at 95% probability. A major improvement was observed for SVM by the correct classification of different forest types. The object-based classification is largely applied on high-resolution spatial images; however, the results of the present work show the robustness of the method also for medium-resolution spatial images.Index terms: object-based classification, territorial management, remote sensing, spatial resolution, land use and land cover. IntroduçãoA gestão territorial demanda uma constante caracterização dos recursos naturais, além de seu monitoramento contínuo, com o objetivo de sua utilização de forma racional. A execução de projetos de levantamento e mapeamento da superfície terrestre têm-se beneficiado ...

Resumo -O objetivo deste trabalho foi avaliar a correlação entre variáveis espectrais e o estoque de carbono da biomassa aérea de sistemas agroflorestais da região de Tomé-Açu, PA. Foram testados 24 índices de vegetação de três grupos (razão simples, diferença normalizada e complexos), gerados a partir de imagens do sensor TM/ Landsat-5, adquiridas em 2008. As variáveis obtidas foram correlacionadas, por meio de regressão linear simples, ao estoque de carbono de quatro classes de sistemas agroflorestais, de diferentes idades e composições florísticas. As correlações obtidas entre as variáveis espectrais e o estoque de carbono foram significativas em 47% dos índices testados e variaram de acordo com as diferenças de biomassa nos sistemas analisados. As melhores correlações foram obtidas pelos índices de vegetação de razão simples e de diferença normalizada, em sistemas agroflorestais jovens, e pelos índices de vegetação complexos, em sistemas agroflorestais mais antigos.Termos para indexação: integração lavoura-pecuária-floresta, Landsat, sensoriamento remoto, uso e cobertura da terra. Correlation of spectral variables and aboveground carbon stock of agroforestry systemsAbstract -The objective of this work was to evaluate the correlation between spectral variables and aboveground carbon stock of agroforestry systems in the region of Tomé-Açu, PA, Brazil. Twenty-four vegetation indices from three groups (simple ratio, normalized difference, and complex), calculated from images of the TM/ Landsat-5 sensor acquired in 2008, were tested. The obtained variables were correlated, by means of simple linear regression, to carbon stock from four agroforestry systems with different ages and floristic composition. The correlations obtained among spectral variables and carbon stock were significant in 47% of the tested indices and changed according to the differences in biomass of the analyzed systems. The best correlations were obtained by the simple ratio and normalized difference indices in young agroforestry systems, and by complex vegetation indices in older agroforestry systems.Index terms: crop-livestock-forest integration, Landsat, remote sensing, land use and land cover.

In this article, we investigated the spatial dependence of the incidence rate by Covid-19 in the São Paulo municipality, Brazil, including the association between the spatially smoothed incidence rate (INC_EBS) and the social determinants of poverty, the average Salary (SAL), the percentage of households located in slums (SLUMS) and the percentage of the population above 60 years of age (POP>60Y). We used data on the number notified cases accumulated per district by May 18, 2020. The spatial dependence of the spatially smoothed incidence rate was investigated through the analysis of univariate local spatial autocorrelation using Moran’s I. To evaluate the spatial association between the INC_EBS and the determinants SAL, POP>60Y and SLUMS, we used the local bivariate Moran’s I. The results showed that the spatially smoothed incidence rate for Covid-19 presented significant spatial autocorrelation (I = 0.333; p<0.05), indicating that the cases were concentrated in clusters of neighbouring districts. The INC_EBS showed a negative spatial association with SAL (I = - 0.253, p<0.05) and POP>60Y (I = -0.398, p<0.05). We also found that the INC_EBS showed a positive spatial association with households located in the slums (I = 0.237, p<0.05). Our study concluded that the households where the population most vulnerable to Covid-19 resides were spatially distributed in the districts with lower salaries, higher percentages of slums and lower percentages of the population above 60 years of age.