Radiação global e difusa diária na região de transição Cerrado-Amazônia do Mato Grosso

• Autor(a) principal: Zamadei, Tamara
• Data de Publicação: 2015
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFMT
• Texto Completo: http://ri.ufmt.br/handle/1/2343
• topic: .; .; CNPQ::OUTROS::CIENCIAS; .; .

Solar radiation is inexhaustible source of energy for all flows between the atmosphere and the land surface, affecting life on the planet. In the context of applications, as Brazil is in full technological development in the areas of renewable energy, agriculture, construction, among others; there is a growing demand for knowledge of seasonal variations in solar radiation levels, considering the spectral and atmospheric attenuation components. Since the costs of acquisition and maintenance of pireliometers to measure the direct radiation are high, the application of shading rings and estimation models allow obtaining the other components of solar radiation. The shadow ring developed by Melo (1994) is inexpensive and can be built with national technology without imports. The northern region of Mato Grosso presents an important vegetation cover (transitional forest between Cerrado and Amazon) and little is known about the effects of the conversion of vegetation and soil within mass and energy exchange with the atmosphere. The routine monitoring for solar radiation allow knowing the effect of geographical variations, astronomical and climatic conditions of the available radiation, as well as assess the effect of human activities on atmospheric processes of a given region. This study aimed to evaluate the seasonality of global and diffuse radiations daily and of atmospheric transmissivity and to propose and validate estimating equations of the diffuse component in the daily partition through correlations of radiometric fractions with the atmospheric transmissivity coefficient and the bright sunshine, for Sinop-MT and region. The values of the radiation were obtained from the Automatic Weather Station Database of University Campus UFMT, from June 2011 to December 2014. The data suffered consistency analysis and were corrected by applying geometric correction factors and anisotropic proposed by Oliveira et al. (2002) and Dal Pai et al. (2011). Also established the classification of sky coverage due to the transmissivity coefficient proposed by Escobedo et al. (2009). For modeling were used two and a half measures (June 2011 to December 2013) and one year for validation (2014). The diffuse radiation showed a similar behavior to that seen at the top of the atmosphere, with maximum values during the period from October to April, and the global radiation values were higher during the dry season. The sky coverage conditions in Sinop varied throughout the year, and in general, the city had 35.06% of days with partially diffuse sky. Through the variation in the transmissivity of solar radiation is possible to conclude that the atmospheric composition affects the amount of energy reaching the earth's surface. The models correlating the radiometric fraction Kd to KT and n/N showed better fit regarding Kd', since there is less influence of the atmospheric composition. The dry months were better estimated with the use of monthly or seasonal models. Concerning the statistical indicatives, the observed values were within the standards described in the literature.