The aim of this research is to evaluate and analyze the forecasting of short-term daily reference crop evapotranspiration by Hargreaves-Samani equation based on temperature forecast. The observed daily meteorological data from 2002 to 2013 at Nanjing Station and the daily weather forecast data for 7-day forecast period from 2012 to 2013 are collected, and the daily ET0 was calculated by using the FAO-56 Penman-Monteith (PM) equation according to daily meteorological data from 2002 to 2012. Furthermore, parameters in the HS equation are calibrated with 2002-2012 PM ET0 values and the calibrated HS equation is adopted for forecasting the 7-day ET0 with weather forecast data from 2012 to 2013. The precision and sensitivity of the forecast results are evaluated and analyzed. Results showed that the forecast result of ET0 based on minimum temperature is more accurate than that on maximum temperature; the statistical indicators of calibrated HS equation are good, indicating the accuracy has improved; and the ET0 estimated from calibrated HS equation are in accordance with the ET0 estimated from PM equation, the accuracy of the HS equation has been significantly improved. Moreover, the accuracy of ET0 declines with the increase of forecast period; the error in ET0 is usually more sensitive to maximum temperature than that to minimum temperature, and the error in ET0 is most sensitive to temperature forecasts in summer, while least sensitive to temperature forecasts in winter.
Key words
reference crop evapotranspiration /
temperature forecast /
Hargreaves-Samani equation /
sensitivity analysis /
precision evaluation
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