Abstract
There are two main objectives in this study, in which one is to develop a methodology for estimating the evaporation from macro-scale hydrologic grid that corresponds to basin-scale or GCM grid scale, and the other to carry out basic sensitivity analysis using bulk method. Macro-scale evaporation formulas, into which the subgrid-scale distribution of related physical equations can be incorporated, are derived from ordinary estimation formulas of evaporation by an areal integration. The sensitivity of the subgrid-scale distributions of surface soil moisture and temperature on the evaporation estimation is examined. The major obtained conclusions are as follows: (1) The estimated values of evaporation are dependent not only on the effect of the distribution but also on other factors and can either be lager or smaller than those values obtained without considering the effect of distribution, (2) The evaporation values are different when different types of distributions with the same mean and variance are employed.
