Measurement of evapotranspiration in a winter wheat field .

Reports that daily evapotranspiration from a winter wheat field on the North China Plain measured by large-scale weighing lysimeter was linearly related to that measured by the Bowen ratio energy balance (BREB) technique. Average of soil evaporation from the post-winter dormancy revival stage to the grain ripening stage; Amount of the net radiation flux Rn was used to warm soil on clear days during winter dormancy; During the revival stage, conductive heat flux G that also used most of the incoming Rn, but the ratio of latent heat flux uE to Rn that increased; Percentage of uE of Rn during the stem-extension stage; Increase of uE/Rn; Percentage of G;. Percentage of uE during the ripening stage; Evaporative fraction (EF) that can be expressed as a function of plant status and atmospheric boundary layer conditions; Relationship between EF and available energy under moderate air temperature and vapor pressure deficit conditions that was examined for five combinations of aerodynamic and canopy conductance; Theoretical relationship that indicates that EF should be highly correlated to soil water content; Correlation that has been difficult to identify under field conditions; Observation that there exists a threshold value of Rn m G, above which EF is less than 1?0, and that the threshold value is lower under soil-water deficit conditions than under abundant soil-water conditions.