Modelo de estimativa da irradiação solar fotossinteticamente ativa para o município de Santa Helena-PR com partição sazonal.

Abstract

The photosinthetically active solar radiation (PAR – Photosynthetically Active Radiation) performs an important function for the plants development, because it is responsible by chemical process that excites the chlorophyll molecules, starting the energy flux required in the photosynthesis. Few researches were made in the state of Parana, because of the instruments costs. This paper aims to show a mathematical model to evaluate the PAR in function of the global solar radiation (Glo) incident on the surface. The data basis were acquired between 01/08/03 and 01/03/05 at Agrometeorological Experimental Station (Estação Agrometeorologica Experimental) from Cascavel/UNIOESTE/PR, set in the city of Santa Helena/PR. The model was generated by simple linear regression using data from one year (23/09/03 to 22/09/04) with seasonal partition, providing the following equations: PARpri = 0,349*Glo (spring); PARver = 0,344*Glo (summer) PARout = 0,373*Glo (autumn); PARinv = 0,368*Glo (winter), with elevated coefficient of correlation that varied from R2 = 86,00% to 97,12%. The remaining data were used to validate the model, obtaining a medium deviation of the errors varying from 6,86% to 15,95% with medium residual pattern deviation in the order of 0,584 1,361(MJ/m2) showing that radiation PAR can be evaluated in function of global radiation with good precision.