“…It provides the primary energy source driving the physical and biochemical processes (transpiration and photosynthesis) of plant and determining forest gross primary productivity (GPP) (Mercado et al, 2009). Unfortunately, the continuous R s measurement is often not available at many forest regions (Adaramola, 2012;Liu et al, 2009a;Polo et al, 2015), and has to be estimated from other available meteorological observations (Angstrom, 1924;Besharat et al, 2013;Prescott, 1940;Yorukoglu and Celik, 2006). The impact of estimated R s (R se ) on ecosystem models are mainly focused on the prediction of crop yields (cotton, maize, peanut, rice, etc.)…”