The analysis of the
temporal and spatial characteristics of
reference evapotranspiration is helpful to(understand) the distribution
and variability of the agricultural and ecological water requirement.Based on the daily meteorological data of more than 200 stations all over China,daily
reference evapotranspiration(ET_0) was(estimated) by using the FAO Penman-Monteith equation.The spatial distribution of ET_0 was obtained by GIS and IDW method was used for spatial interpolation.In China,the largest ET_0 was found to be more than 1500 mm in northwest and south region,and the smallest is found to be 600 mm to 700 mm in the northeast region and Sichuan Basin.In addition,the ET_0 in summer contributes most of a year.Then four representative stations were selected to analyze the temporal variation of ET_0 values and the effects of meteorological data on ET_0.It is(concluded) that in recent years ET_0 in arid areas tends to become smaller because of the decreases of solar radiation and wind speed,while in humid areas ET_0 is relatively stable.