Variation of the radiation and energy balance of the irrigated sugarcane in the semiarid Brazil

The objective of this work was to analyze the variations in the magnitudes and partition of the radiation and energy balance components, obtained during the growth period of the irrigated sugarcane (variety RB92579). The experiment was carried out in Juazeiro-BA, located in the Brazilian semiarid region. The sensible (H) and the latent (LE) heat fluxes in the air were estimated by means of the Bowen ratio energy balance (BREB). The crop growth was also monitored. In a preliminary analysis of this method, it was verified that 62.7% of the collected data presented physical consistence to be used for estimating the H and LE components. It was observed that the mean value of the Rn/Rg ratio was equal to 59 +/- 5%, with smaller values occurring at the beginning and at the end of sugarcane crop cycle, while the magnitude of long wave radiation balance (BOL) was intensified when the leaf area index (LAI) was reduced. Also, it was noticed that the mean value of the albedo was 23 +/- 3% and that 81% of the available energy was destined to the latent heat flux, while the sensible heat in the air (H) and in the soil (G) represented 16 and 3%, respectively.