Potato ground cover and spectral data were measured in the Columbia Basin during the 1990 growing season. Three spectral were correlated with ground cover; normalized difference, near infrared-red ratio, and the first derivative of the spectral curve at 750 nm. All models were statistically significant at the 99% level. Normalized was most correlated followed by the near infrared-red ratio, and the first derivative of the spectral curve at 750 nm. / Graduation date: 1992

Made available in DSpace on 2014-12-17T15:03:31Z (GMT). No. of bitstreams: 1 HelioNB_DISSERT.pdf: 3257032 bytes, checksum: c4c8b0f640d55be078cd61d2e68686c0 (MD5) Previous issue date: 2013-04-26 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / With the need to deploy management and monitoring systems of natural resources in areas susceptible to environmental degradation, as is the case of semiarid regions, several works have been developed in order to find effective models and technically and economically viable. Therefore, this study aimed to estimate the daily actual evapotranspiration (ETr) through the application of the Surface Energy Balance Algorithm for Land (SEBAL), from remote sensing products, in a semiarid region, Serid? of the Rio Grande do Norte, and do the validation of these estimates using ETr values obtained by the Penman-Monteith (standard method of the Food and Agriculture Organization-FAO). The SEBAL is based on energy balance method, which allows obtaining the vertical latent heat flux (LE) with orbital images and, consequently, of the evapotranspiration through the difference of flows, also vertical, of heat in the soil (G), sensitive heat (H) and radiation balance (Rn). The study area includes the surrounding areas of the Dourado reservoir, located in the Currais Novos/RN city. For the implementation of the algorithm were used five images TM/Landsat-5. The work was divided in three chapters in order to facilitate a better discussion of each part of the SEBAL processing, distributed as follows: first chapter addressing the spatio-temporal variability of the biophysical variables; second chapter dealing with spatio-temporal distribution of instant and daily radiation balance; and the third chapter discussing the heart of the work, the daily actual evapotranspiration estimation and the validation than to the study area / Com a necessidade de se implantar sistemas de monitoramento e gest?o dos recursos naturais em ?reas suscept?veis ? degrada??o ambiental, como ? o caso das regi?es semi?ridas, diversos trabalhos t?m sido desenvolvidos a fim de encontrar modelos eficazes e vi?veis t?cnica e economicamente. Diante disso, este trabalho teve como objetivo estimar a evapotranspira??o real (ETr) di?ria atrav?s da aplica??o do Surface Energy Balance Algorithm for Land (SEBAL), a partir de produtos de sensoriamento remoto, em uma regi?o semi?rida, Serid? norte rio-grandense, e fazer a valida??o dessas estimativas utilizando valores de ETr obtidos pelo m?todo de Penman-Monteith (m?todo padr?o da Food and Agriculture Organization - FAO). O SEBAL baseia-se no m?todo do balan?o de energia, que possibilita a obten??o do fluxo vertical de calor latente (LE) com imagens orbitais e, consequentemente, da evapotranspira??o, atrav?s da diferen?a dos fluxos, tamb?m verticais, de calor no solo (G), calor sens?vel (H) e o saldo de radia??o (Rn). A ?rea de estudo compreende o entorno do reservat?rio Dourado, situado no munic?pio de Currais Novos/RN. Para a implementa??o do algoritmo foram utilizados cinco imagens TM/Landsat-5. O trabalho foi divido em tr?s cap?tulos a fim de possibilitar uma melhor discuss?o de cada parte do processamento do SEBAL, ficando assim distribu?dos: primeiro cap?tulo abordando a variabilidade espa?o-temporal das vari?veis biof?sicas; segundo cap?tulo tratando da distribui??o espa?o-temporal do saldo de radia??o instant?neo e di?rio; e o terceiro cap?tulo discutindo o cerne do trabalho, a estimativa da evapotranspira??o real di?ria e a valida??o da mesma para a ?rea estudada