Study on the Characteristics of Evapotranspiration in Semi-Arid Region and its Extension to Wide Area by Remote Sensing

本文研究了华北平原半干旱环境下的蒸散发，在华北平原沿着N38□线的三个站进行了热量收支的测定。研究揭示了冬小麦田典型的热量收支及其与土壤水分、光谱反射率等地表状态变量的相关性，主要观点和成果如下：1）蒸渗仪和波文比能量平衡法测定的冬小麦热量收支日变化2）与生育期相关的热量收支季节变化3）灌溉通过土壤水分变化对蒸散的影响4）蒸散与作物传导的关系5）土壤水分与作物传导的关系气孔阻力/导度的日变化和季节变化6）气孔阻力与土壤水分的关系7）光谱反射率和植被指数的季节变化

This research treats evapotranapiration in semi-arid environment in NCP(North China Plain), Heat budget components were measured in three stations along N38□ line in NCP. The research revealed the typical heat; budget in winter wheat field, and its relevance to surface state variables, such as soil moisture, spectral reflectance, and so on. The major viewpoints and outcomes are summarized as follows :1) Diurnal changes in heat budget in winter wheat field measured by lysimeter and bowen ratio energy balance methods2) Seasonal changes in heat budget in relation to the growing stages3) Influence of irrigation to evapotranspiration through soil moisture variation4) Relationship between evapotranapiration and crop conductance5) Diurnal and seasonal variations in stomatal resistance/conductance6) Relationship between stomatal resistance and soil moisture7) Seasonal variations in spectral reflectance and vegetation index