CONTRIBUTION TO THE STUDY OF GLOBAL RADIATION AND INSOLATION IN THE MATO GROSSO DE GOIÁS MICROREGION

Abstract

This work studies the month average of daily global solar radiation, daily relative global solar radiation, daily sunshine duration and daily relative sunshine duration, for the conditions in Goiânia county and surrounding counties, Goiás — Brazil (latitude: 16°41'S, longitude: 49°17’W GRW, and altitude: 680.00m). It's observed that: a) global solar radiation is maximum in October and minimum in July; b) relative global solar radiation is maximum in August and minimum in November; c) sunshine duration is maximum in June and minimum in November; d) relative sunshine duration is maximum in June and minimum in November. Correlation between the month average of daily relative global solar radiation and of daily sunshine duration allowed to conclude the linear equation: Kg = Ka (0.49 n/N), where the letters mean: Kg = daily global radiation (ly/day); Ka = daily solar radiation on the top of atmosphere (ly/day); n = daily duration of sunshine (hr/day); N = daily maximum duration of sunshine (hr/day). The methodology adopted was the one proposed by PRESCOTT (1940) and PENMAM (1948), as cited by BLACK et alii (1954), in order to estimate parameters ";a"; and “b”, in the equation Kg/Ka = a + b (n/N), which correlates the sunshine ratio (n/N) to the relative solar, radiation (Kg/Ka) by linear regression analysis. The equation found showed a correlation coefficient which was equal to 0.95 with significance at 0.1% probability level.