The aim of the work was to characterize the temporal variability of ten-day evapotranspiration series, considering the actual evapotranspiration (ETa) and the ratio between actual and potential evapotranspiration (ETa/ETP). Data between 1948 and 2008 were collected with a weather station in Campinas, State of São Paulo, Brazil. Evapotranspiration calculation considered three values of soil water availability (SWA): 50, 100, and 150 mm. Based on autocorrelation function, it was detected a significant level of temporal persistence on ETa and ETa/ETP series. The acf also has indicated that this temporal persistence tends to increase due to high SWA values. The spectral analysis has shown a decreasing power of these series after 1976. The El Niño/southern oscillation influence on ETa and ETa/ETP temporal variability was not conclusive. The Seasonal Mann-Kendall test has shown increasing trends on ETa series in the months of January, May, July, September, November and December. The ETa/ETP series was little affected by the increasing trends detected on ETP series.
Climate change; temporal variability; trends
