The RadEst program allows evaluating daily global solar radiation values for a location at a given latitude, and it allows estimating daily values. Four models are available to estimate daily radiation from air temperature data; they include and are all derived from the model proposed by Bristow and Campbell. All the models estimate atmospheric transmissivity of global solar radiation based on the difference between maximum and minimum temperature. The estimated value of radiation is calculated as the product of the estimated transmissivity times the value of potential radiation outside the earth atmosphere. Utilities allow a graphical evaluation of the estimates and compute statistical indices for model/location comparison. For each model, parameters can be fitted using iterative procedures either minimizing the amount or the pattern of residuals. One year or more than one year (at most twenty) of daily data can be used to estimate one parameter for each model. Estimated values can be saved as ASCII files. Trends over years in measured data can be evaluated graphically. Constant bias in measured radiation data can be evaluated and corrected, saving the corrected files. Version 3 includes a new model specifically developed for tropical sites. Also, it includes a modular model which allows including/excluding different components from the three models implemented. A sample data set of tropical and temperate sites is provided. A parameter file for tested locations is also provided. Reporting capabilities allow browsing and printing the analysis performed; reports can be saved and exported in a variety of formats, including MS Excel and HTML. Estimates of potential evapotranspiration are made and saved with either the Penman-Monteith or the Priestley-Taylor method, using both the measured and the estimated radiation data. A batch run utility allows processing easily a large number of files.
Comments (1)