Monthly Potential Evapotranspiration of Thailand

บทคัดย่อ

Monthly potential evapotranspiration was studied using 3 well-know methods of Penman-Monteith, Modified Penman and Pan Evaporation. Long term average climatological data from 74 climatological stations (30-year period) and 29 agroclimatological stations (25-year period) were used in the study. ETo calculated by Penman-Monteith method was very similar to those calculated from Pan evaporation but was 18.5% lower than those calculated by Modified Penman method. Mean monthly ETo of Thailand varied between 101 mm in December to 148 mm in April. The average annual ETo was 1,434 mm. The minimum annual ETo was 1,200 mm at Umphang climatological station while the maximum 1,683 mm at Chainat climatological station.