R code for identification and correction of Photosynthetically Active Radiation sensor drift

R code was created to model maximum solar radiation and photosynthetically active radiation (PAR) based on location, date, temperature, atmospheric pressure and humidity. Additional code compares actual data with the predicted peaks in the solar radiation curves and identifies places where there is significant deviation from the predicted maximum and adjusts the output data to make it so that monthly peaks (assuming at least one day in the month was clear!) correspond to the predicted maximum. PAR is calculated as 45% of the solar radiation.