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Search Results: 1 - 10 of 216873 matches for " Bernardo B. da Silva "
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Actual Evapotranspiration Estimation Using Remote Sensing: Comparison of SEBAL and SSEB Approaches  [PDF]
Bergson G. Bezerra, Bernardo B. da Silva, Carlos A. C. dos Santos, José R. C. Bezerra
Advances in Remote Sensing (ARS) , 2015, DOI: 10.4236/ars.2015.43019
Abstract: The main objective of this paper was to evaluate the daily actual evapotranspiration (ET) accuracy obtained by remote sensing algorithms when compared with Bowen ratio measurements performed in the cotton fields. The experiment was conducted in a cotton experimental field of EMBRAPA located in Ceará State, Brazil. Seven TM Landsat-5 images acquired in 2005 and 2008 were used to perform SEBAL and SSEB algorithms. The comparison between the estimated values by remoting sensing algorithms and the measured values in situ showed an acceptable accuracy. Besides, SSEB algorithm showed to be an important tool for ET analysis in the semi-arid regions, due to the fact that it does not need the meteorological data to solve the energy balance, but only the average temperature of the “hot” and “cold” pixels. Additionally, SSEB presents simpler processing than SEBAL algorithm that needs to solve an iterative process to obtain the sensible heat flux values.
Estimativa da evapotranspira??o real diária utilizando-se imagens digitais TM - Landsat 5
Bezerra, Bergson G.;Silva, Bernardo B. da;Ferreira, Nelson J.;
Revista Brasileira de Meteorologia , 2008, DOI: 10.1590/S0102-77862008000300005
Abstract: quantification of evapotranspiration is of great importance for hydrological and meteorological modeling and indispensable for water management of irrigated crops. in this sense the main objective of this study was the estimation of actual daily evapotranspiration (etr), in local and regional scale, utilizing the sebal (surface energy balance algorithm for land). the tm - landsat 5 images and weather data were used in order to assess the energy balance components. the studied area is located in cariri region, ceará state, and is composed by irrigated areas, native vegetation and part of the chapada do araripe reserve. four tm - landsat 5 images of september 29th, october 15th, october 31st and november 16th of 2005, were used. daily etr was estimated based on the density of latent heat flux, obtained as residue of the energy balance equation. the application of the sebal algorithm includes some steps as radiometric calibration, estimation of the reflectance and albedo, emissivity and vegetation index, based on the reflective bands of the orbital sensors and further on the surface temperature (thermal band) for the tm - ladsat 5. two irrigated fields of castor bean and cotton were used do validated the etr estimated values. the reference evapotranspiration was obtained by fao-penman-monteith method. the mean daily etr over the studied area presented values of 3.8, 3.7, 4.6 and 3.4 mm.dia-1 on 29/09, 15/10, 31/10 and 16/11, respectively. when compared to measured data in the castor bean (ricinus communis l.) and cotton (gossypium hirsutum) irrigated crops, the etr values obtained with sebal present differences smaller than 1,0 mm day-1, showing its importance and accuracy.
Seasonal Patterns of the Energy Balance Components in a Mango (Mangifera indica L.) Orchard grown in Northeast Brazil
Vicente de Paulo R. da Silva,Pedro V. de Azevedo,Bernardo B. da Silva
Agricultural Journal , 2013,
Abstract: Measurements of energy balance components were obtained in a field experiment to analyze the energy balance components on a mango orchard during two fruiting cycle. The Bowen Ratio-energy Balance (BREB) method was applied in order to estimate the energy fluxes while the reference evapotranspiration (ETo) was obtained according to FAO 56. It was establish a relationship between latent heat flux (LE) and the net Radiation (Rn) for three availability energy levels. The results showed that during both field campaigns LE was found to be the major component of the energy balance, comprising more than 80% of the available energy, while G was always a small component, comprising less than 6% of total Rn. The daily mean values of ETo and ETc were similar in both measurement periods even though these were higher slightly in the 1998 fruiting cycle than values observed in 1999. For the 1998 and 1999 fruiting cycles the cumulative estimates of crop evapotranspiration (ETc) were 719.3 and 675.8 mm, respectively, while the ETo for these two experimental periods were 819.8 and 784.8 mm, respectively. The determination coefficients (r2) values for the linear relationships between of net radiation and latent heat flux varied according to the available energy level, ranging from 0.82 for the moderate level in the 1998 fruiting cycle to 0.99 for the high available energy in 1999.
Mapeamento do saldo de radia??o com imagens Landsat 5 e modelo de eleva??o digital
Di Pace, Frederico T.;Silva, Bernardo B. da;Silva, Vicente de P. R. da;Silva, Saulo T. A. da;
Revista Brasileira de Engenharia Agrícola e Ambiental , 2008, DOI: 10.1590/S1415-43662008000400009
Abstract: net radiation is an important component of the surface energy balance in studies of evapotranspiration of irrigated crops and in evaporation of hydrological basins. the objective of this research was to determine the surface radiation balance, by using multispectral imagery of the thematic mapper (landsat 5 satellite). in this study the sebal (surface energy balance algorithm for land) and dem (digital elevation model) were used in order to correct the albedo and vegetation indices under the influence of the slope aspects were used for each study area. tm (thematic mapper) imageries were used for two different dates (december 4, 2000 and october 4, 2001). the calculations were accomplished with and without use of the dem. the land surface temperature and albedo values with dem were larger than without dem in both years, for two selected areas. results also show that for obtaining net radiation based on imagery of the tm - landsat 5 the topographical effects of the study area must be considered.
Desempenho de modelo climático aplicado à precipita??o pluvial do Estado de Pernambuco
Silva, Bernardo B. da;Ferreira, Maria A. F.;Silva, Vicente de P. R. da;Ferreira, Rafael da C.;
Revista Brasileira de Engenharia Agrícola e Ambiental , 2010, DOI: 10.1590/S1415-43662010000400007
Abstract: in this research the performance of a probabilistic climate forecast model applied to seasonal rainfall of pernambuco state was assessed. four rainy seasons (ec) were defined and each one was subpided in two periods - initial (xi) and final (yi) - for three mesorregions of pernambuco state. the methodology proposed consisted in adjusting proportions of zi (ratio of accumulated rainfall of the first period (xi) and the total rainfall of each ec (xi + yi) in the corresponding ec, year by year, over a time series of at least 30 years, to the beta distribution for obtaining the minimum accumulated rainfall expected at 80% probability level for the period yi of ec. the validation of the model was verified with data collected from 1994 to 2002 for each ec. the lilliefors goodness-of-fit test was used to evaluate the adjustment of model for each set of zi values. results showed a good agreement between the empirical distribution and beta model. there was an increasing trend of lesser agreement in the prediction of ymin during dry or rainy years and good agreement in years considered as normal. the performed model showed success in the prognostics of ymin in more than 80% of the studied localities, over the validation period.
Fluxos de energia e desenvolvimento da cultura do abacaxizeiro
Souza, Cleber B. de;Silva, Bernardo B. da;Azevedo, Pedro V. de;Silva, Vicente de P. R. da;
Revista Brasileira de Engenharia Agrícola e Ambiental , 2008, DOI: 10.1590/S1415-43662008000400011
Abstract: the canopy of the pineapple crop changes considerably during the growing season, from a leafless stage to a fully closed canopy at the end of the productive cycle. in order to evaluate the effects of the energy balance components on the developmental stage of the pineapple crop, a field experiment was carried out from march, 2001 to july, 2002 with pineapple crop, cv. perola, cultivated under supplemental irrigation conditions in the state of paraíba, brazil. the method of energy balance based on the bowen ratio was used to obtain energy balance components during the experimental period. the energy balance components were strongly affected by leaf area index and plant height during all developmental stages of the canopy, especially the sensible heat flux. results showed that the dry matter weight is totally independent of the energy partitioning. the sensible heat flux varied in function of the volume of water applied in irrigation during the experimental period.
Crescimento e rendimento do abacaxizeiro nas condi??es climáticas dos Tabuleiros Costeiros do Estado da Paraíba
Souza, Cleber B. de;Silva, Bernardo B. da;Azevedo, Pedro V. de;
Revista Brasileira de Engenharia Agrícola e Ambiental , 2007, DOI: 10.1590/S1415-43662007000200002
Abstract: a field experiment was carried out with the pineapple, cultivar pérola, in santa rita in the state of paraíba, brazil, during the period from march, 2001 to june, 2002. the development and yield of crop under supplemental irrigation conditions was evaluated in order to obtain information for improving crop management in the region. the growth and yield variables were compatible with those obtained in other studies. the results showed that the leaf area index (lai) reached a value of 12, 308 days after planting and the fruits with weight above 1.7 kg reached 60% of the total harvested fruits. the fruit of 2nd category, with weight between 1.3 and 1.7 kg, represented 30% of the total fruit production while the remaining 10% of fruits harvested with weight less than 1.3 kg, were considered of lower quality and sent to the juice and animal food industry. the pineapple crop, cv pérola, grown under climate and costal table land soil of santa rita, pb, presented lai, size of fruit and yield greater than those obtained in other regions of brazil, even in irrigated areas.
Simula o do saldo de radia o na Serra da Mantiqueira Simulation of net radiation in the Mantiqueira mountain
Pabricio M. O. Lopes,Dalton M. Valeriano,Bernardo B. da Silva,Geber B. de A. Moura
Revista Brasileira de Engenharia Agrícola e Ambiental , 2013,
Abstract: A influência do desmatamento da Mata Atlantica sobre o microclima da Serra da Mantiqueira ainda n o é totalmente compreendida. Para conhecer as consequências do desmatamento sobre o clima serrano é necessário realizar estudos sobre o balan o de radia o na superfície. A falta de dados possibilita conjugar imagens de satélite com dados meteorológicos em um Sistema de Informa o Geográfica na determina o do balan o de radia o. O presente estudo teve por objetivo avaliar o modelo MTCLIM em dias de céu claro ou nublado para simular o balan o de radia o na Serra da Mantiqueira, divisa entre os estados de S o Paulo, Minas Gerais e Rio de Janeiro, Brasil. Imagens diárias, semanais e dezesseis dias do sensor MODIS disponíveis em 2003 foram utilizadas em rotinas específicas do MTCLIM. Alvos específicos foram selecionados para avaliar o comportamento do balan o de radia o. Observou-se que o balan o de radia o acompanhou a topografia local e é influenciado pelo tipo de uso da terra. Conclui-se que a temperatura da superfície contribui para aumentar a temperatura do ar implicando em diminui o do balan o de radia o sobre pastagem. O modelo MTCLIM demonstrou boa correla o para a temperatura do ar (R2 = 0,82) e para a radia o solar global (R2 = 0,71). The influence of deforestation of the Atlantic Forest on the microclimate of the mountain Mantiqueira is not yet fully understood. To understand the consequences of deforestation on the highland climate research is needed about the surface radiation balance. The lack of data allows combining satellite images with meteorological data in a Geographic Information System in determining the radiation balance. The study aimed to evaluate the MTCLIM model in cloudless days or cloudy sky and simulate the radiation balance in the Mantiqueira mountain, between S o Paulo, Minas Gerais and Rio de Janeiro, Brazil. Daily images, weekly and sixteen days MODIS available in 2003 were used in specific routines from MTCLIM. Specific targets were selected to evaluate the behavior of the radiation balance. It was observed that the radiation balance followed the local topography and is influenced by the type of land use. It follows that the surface temperature contributes to elevate the air temperature, resulting in lesser radiation balance on pasture. The MTCLIM model showed good correlation for air temperature (R2 = 0.82) and solar radiation (R2 = 0.71).
Sazonalidade de variáveis biofísicas em regi?es semiáridas pelo emprego do sensoriamento remoto
Rodrigues, Joseilson O.;Andrade, Eunice M. de;Teixeira, Adunias dos S.;Silva, Bernardo B. da;
Engenharia Agrícola , 2009, DOI: 10.1590/S0100-69162009000300012
Abstract: to investigate the rainfall regime effects over the albedo, ndvi (normalized difference vegetation index), net radiation and soil heat flux in a semiarid region (northeast of brazil), a study in the trussu watershed was developed by using remote sensing. the study focuses on two images (landsat 7 etm+) provided by instituto nacional de pesquisas espaciais (inpe), from october 25, 2000 and july 24, 2001, each of them having a different rainfall regime (dry and wet seasons). the images were analyzed by using the sebal algorithm (surface energy balance algorithm for land). the results showed that the amount of rainfall affected the investigated variables, and the highest values of albedo were registered during the dry season. the ndvi presented high sensibility to rainfall regime, pointing out a high vegetation potential recover during the rainfall season. the ndvi along the trussu river was up to 0.39, expressing the repair zone preservation. the watershed vegetation showed a high resilience power expressed by ndvi values in the year of 2001. net radiation and soil heat flux were greater in the dry season, in this way expressing the effect of humidity on the energy balance.
Avalia??o dos efeitos atmosféricos no albedo e NDVI obtidos com imagens de satélite
Bezerra, Marcus V. C.;Silva, Bernardo B. da;Bezerra, Bergson G.;
Revista Brasileira de Engenharia Agrícola e Ambiental , 2011, DOI: 10.1590/S1415-43662011000700009
Abstract: the albedo is an important element in studies related to radiation and energy balances. consequently, changes in different biomes bring major implications for human and animal comfort. accordingly, the monitoring of the albedo by orbital images enables to identify the anthropic influence of large areas and their environmental impact. this work was developed with the objective of assessing the impact of atmospheric correction at surface albedo and the ndvi using the traditional method of sebal (bastiaanssen, 2000) and atmospheric correction band to band (allen et al., 2007b) for four landsat 5 tm images covering cariri mesoregion of ceará state. the results showed decrease in the surface albedo and increase in ndvi, corrected for atmospheric effects for all sample areas. according with student test there was significant difference between the albedo and ndvi under the two methods, significant at 0.01 level.
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