Generation of solar radiation values for use in weather files of crop simulation models

Abstract

A user friendly computer program for generating solar radiation values was developed for three sites (Mayagüez, Ponce and Isabela) in Puerto Rico. The program produces solar radiation data compatible with that of the weather files of the crop models in the Decision Support System for Agrotechnoiogy Transfer (DSSAT), developed by the International Benchmark Sites Network for Agrotechnology Transfer (IBSNAT). The program randomly generates solar radiation values within a range determined by statistical analysis of available observed solar radiation data. A chi-square goodness-of-fit test showed that, for a given Julian day and site, the random values produced are uniformly distributed (non-biased) over the pre-determined confidence interval range (a = 0.05). Results also indicate that the annual trend in the program-generated solar radiation values throughout the year was similar to that of the observed values. Using the randomly generated solar radiation values, the output parameters (pod yield, seed yield, shelling percentage, weight per seed, seed number, maximum LAI, biomass, stalk and harvest index) of the DSSAT dry bean model were similar to the variables generated with observed solar radiation data.