The effects of heterogeneity within an area on areally averaged evaporation

✍ Scribed by Dr Tosiyuki Nakaegawa; Taikan Oki; Katumi Musiake

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 679 KB
• Volume: 14
• Category: Article
• ISSN: 0885-6087
• DOI: 10.1002/(sici)1099-1085(20000228)14:3<465::aid-hyp949>3.0.co;2-g

✦ Synopsis

Unresolved heterogeneity in a numerical simulation has a signi®cant impact on the hydrological land surface processes, and the areally averaged quantities do not give the actual values of dierent phenomena. In the present study, the equation for computing the areally averaged evaporation taking account of the two hierarchical distributions of the physical quantities, namely subarea and intrasubarea scale distributions, and its components are explained based on the equation. Using the derived equation, numerical experiments to identify the eect of the intrasubarea scale distribution of the temperature and soil moisture content at soil surface are conducted. The estimated evaporation by the mean parameter method can be in the opposite direction because of a slight underestimation of the area representative saturated speci®c humidity. The eect of the soil moisture distribution is signi®cantly larger than that of the temperature distribution. Normal and uniform distributions with the same mean value and variance of the soil moisture have dierent eects on the area representative evaporation and the dierence between the two reaches some 10%.