Predicting daily photosynthetically active radiation from global solar radiation in the Contiguous United States

摘要: Abstract An investigation on the daily photosynthetically active radiation ( PAR ) with global solar R s is conducted at 7 surface budget monitoring stations across Mainland United States by exploiting a 3 years (2009–2011) data achieve. The clearness index, diffuse fraction and skylight brightness along dew point temperature cosine of zenith angle are used to generate empirical relationships for predicting from . Records 2009 2010 employed model establishment, while records 2011 validation. accuracy models’ predictions evaluated four statistics parameters, including coefficient determination, root mean square error, percentage error relative standard deviation. Results show that polynomial taking index as main parameter plus has best performance out ten proposed models. And capable be indicator prediction, substitute combination brightness.