Análisis de comportamiento de la evapotranspiración de referencia (ETo) en un ecosistema de páramo mediante la ecuación combinada de Penman-Monteith

Abstract

Reference evapotranspiration (ETo) is a key parameter in hydrological, ecohydrological and biohydrological investigations. Nevertheless, it has been the less studied hydrological process because of the lack of high quality meteorological data. Therefore, its behavior in the paramo ecosystem is little known. This research was carried out with meteorological data sampled every 5 minutes during almost 2 years in the main station of the hydrometeorological observatory of Grupo de Ciencias de la Tierra y el Ambiente (GCTA) located in the páramo of Zhurucay. The objective was to assess the errors in the estimation of ETo due to different reasons: (i) due to the smoothing committed when meteorological variables are averaged in different temporal scales, (ii) due to the estimation of missing variables from other measured and (ii) due to the sampling frequency of meteorological data. Averages of the variables were calculated in an hourly, daily and monthly basis in order to estimate ETo in those 3 time scales and evaluate the error in each one of them. In monthly and daily estimations of ETo the biggest errors were observed when missing variables were estimated from others measured, finding average errors higher than 40% in monthly estimations and higher than 20% in daily estimations. Using a smaller sampling frequency resulted always in average error lower than 2% on these 2 scales. Also the effect of the sampling frequency in the hourly estimation of ETo was evaluated, finding a great uncertainty on the precision when using sampling frequencies higher than 5 minutes.