A model for calculating daily near infrared solar radiation

In this work, a semi-empirical model for calculating daily global near infrared solar radiation (NIR) was developed. The model is written in the form of the ratio of daily global NIR (H_NIR) to daily global broadband solar radiation (H) as an empirical function of atmospheric parameters influencing H_NIR/H namely, precipitable water (w), total ozone column (O₃), aerosol optical depth (AOD) and cloud index (n). A 5-year period (2009-2013) data of H_NIR, H, w, O₃, AOD and n obtained from 4 meteorological stations situated in the main regions of Thailand were used to calculate the empirical coefficients of the model. This model was tested against an independent measured data set. It is found that HNIR calculated from the model and that from the measurement are in good agreement, with the difference in terms of root mean square error of 7.7% and mean bias error of 5.3%. (paper)