Análise de tendência da evapotranspiração e de suas variáveis climatológicas intervenientes no Estado do Ceará-BR

Abstract

This study analyzes annual trends in measured meteorological variables and in the reference evaporation (ETo) estimated from them, in eight climatological stations in Ceará State, Brazil. Two statistical tests for trend analysis were used - Mann-Kendall and linear regression. It is shown that maximum temperature (Tmax) presented statistically significant increasing trend in five stations, as well as the minimum temperature (Tmin), which also showed a positive trend in three stations. Wind speed (U) and sunshine hours (S) series had positive and negative trends in two stations. The relative humidity (RH) showed negative trends in two stations and positive trend in one. These irregular trend patterns in the cited variables, only directly impacted ETo in three stations. It seems that the increasing trend in ETo was probably due to a significant increase detected in maximum temperature (Tmax) and minimum air temperature (Tmin), probably not fully offset by the decrease in wind speed (U) and relative humidity (RH). A significant increase trend in ETo trends was observed in Iguatu (+) 47.45 mm/decade, Crateus (+) 37.90 mm/decade and Fortaleza (+) 5.55 mm/decade.