Evapotranspiration determination with satellite and reanalysis data using Google Earth Engine

Vertical flows, within the hydrological cycle, are one of the most relevant variables in the plains, since slopes vary between 0 and 5%, and horizontal flows are not significant. In this sense, evapotranspiration plays a fundamental role in water management since about 85% of the water leaving the system does so through this process, requiring precise quantification. The main objective is to calculate potential and actual evapotranspiration (ETp and ETa) with satellite and reanalysis data using Google Earth Engine platform. For its calculation, the Priestley-Taylor (PT) equation combined with soil moisture information was used, with a spatio-temporal resolution of 250 x 250 m every eight days, in the Argentine Pampas region (APR). The product was valued in seven stations of the APR, whose results showed, for ETp, an R-RMSE (Robust Root Mean Square Error) of 0.5 mm d(-1), a systematic error (Median) of 0.3 mm d(-1), and the random error (RSD-Robust Standard Deviation) of 0.5 mm d(-1); while, for ETa, these values are 0.6, -0.2 and 0.5 mm d(-1), respectively. The overall results show that the method used is a valid tool to characterize ET in the APR and that it can be used to analyze its spatio-temporal variability under different extreme conditions and to carry out applied environmental studies.