Comparing the use of past and forecast weather data for estimating reference evapotranspiration

摘要

The reliability of short-term weather forecast provided by COSMO model in simulating reference evapotranspiration (ET0) was evaluated in 7 study sites distributed in 4 countries (Italy, Norway, Romania and Spain). The main objective of the study was to assess the optimal scenario for calculating ET0, using the FAO-56 Penman-Monteith (PM) equation, by separately considering the accuracy in the use of "past" and "forecast" data input. Firstly, each forecasted variable (air temperature, T-air; relative humidity, RH; wind speed, u(2); solar radiation, R-s) and ET0 were compared with in situ observations at hourly and daily scales. Moreover the seasonality effect in the forecast performance was evaluated. Secondly, simulated ET0 were computed every three days with: (i) a "past scenario" that used the observed data input measured in situ during the previous three days, (ii) a "forecast scenario" that used the forecasted input variables for the next three days; and compared with (iii) actual ET0 obtained from the in situ measured data.