Performance of Daily FAO56-PM ET₀ Model Estimates under limited data conditions at Arid Jodhpur District of Rajasthan

This study was conducted for arid Jodhpur district to compare performance of standard FAO56-PM model with derived individual meteorological parameters, their combinations and complete dataset estimates and to decide the minimum meteorological parameters required to compute at par FAO56-PM estimates. The performance of 33 cases of derived individual parameters & their combinations in comparison to complete dataset FAO56-PM estimates was evaluated on the basis of statistical indices and ranking based on summative form of Global performance indicator values. Solar radiation was found most important parameter, followed by relative humidity and wind speed. The saturation vapour pressure estimated using mean air temperature showed least influence on FAO56-PM estimates while, missing relative humidity data obtained by considering dew point temperature 3°C lesser than minimum air temperature extended good results. The missing solar radiation data can be estimated accurately by maximum and minimum air temperature while, long-term average wind speed of study area in absence of wind speed data extended better FAO56-PM estimates. The minimum & maximum and/or mean air temperature along with long-term average wind speed are minimum meteorological data requirement to compute at par FAO56-PM estimates.