The balance of radiation represents the energy gains and losses on the surface, and can be estimated by summing the four components of surface radiation (incident and reflected solar radiation, radiation emitted by the surface and emitted by the atmosphere). The SiB2 model represents ecosystems and provides estimates of surface energy changes. In this work, five different incident long wave estimation equations were tested to verify the influence of this component on the closure of the radiation balance for the SiB2 model. The results show the underestimation of the radiation balance of the SiB2 model when compared to the experimental data. Thus, it is inferred the need for calibration of incident long-wave radiation equations for use in models for local simulations