湿润气候区非均匀地表平均蒸散发率参数化方案研究

从水文过程的物理机制出发,提出湿润气候区平均蒸散发率的一种统计-动力参数化方案.将陆面蒸散发过程的复杂机制分解为地表层裸土及植被两种下垫面的土壤水分饱和区与非饱和区影响下的通量贡献.从理论上推导出考虑土壤含水量次网格尺度非均匀性的区域蒸散率解析表达式.根据湿润气候区土壤水分空间分布PDF的特点,给出适用于湿润气候区的平均蒸散发计算式.以长江三角洲为例进行的数值试验证明其合理性与可行性.

Parameterization scheme for averaged evapotranspiration over heterogeneous surface in moist climate region

Based on the physical mechanism of hydrological process,a parameterization scheme for regional averaged evapotranspiration with statistical-dynamic theory is established in the moist climate region.The regional averaged evapotranspiration is supposed to be constituted of the evaporation from bare land surface and the evapotranspiration from vegetation surface.At the same time the influence of proportion of saturation and non-saturation area of surface soil humidity in the examination region on the estimation of the evaporation or the vapotranspiration is considered.A expression for estimating regional averaged evapotranspiration is educed by means of the probability density function of soil humidity over heterogeneous surface for moist climate region.The reliability and workability of the expression are proved in the Yangtze Delta region.