Hydric balance and climatic classification of the city of Porto Nacional, state of Tocantins, inserted in the Legal Amazon, Brazil

The objective of this study was to carry out the Climatological Water Balance in conjunction with the climatic characterization, using precipitation and air temperature data in the municipality of Porto Nacional, belonging to the Legal Amazon, Tocantins state, by Thornthwaite and Mather (1955) for 20 years, from 1997 to 2016. From the results of potential evapotranspiration, real evapotranspiration, water surplus and water deficit, the water, aridity and humidity indices were established based on the number of continuous data from the conventional meteorological station , of WMO Code 83064, of the National Institute of Meteorology, located in the district Setor Aeroporto, municipality of Porto Nacional. The climatic formula obtained for the municipality of Porto Nacional was C2wA'a ', which characterized the climate in wet subhumid, with two well defined seasons, rainy and dry, being the dry season in the winter season where it presents moderate water deficiency and megatérmico, with values high annual evapotranspiration potential, with 28.29% of this evapotranspiration concentrated in the summer season.