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The effects of heterogeneity within an area on areally averaged evaporation
Author(s) -
Nakaegawa Tosiyuki,
Oki Taikan,
Musiake Katumi
Publication year - 2000
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/(sici)1099-1085(20000228)14:3<465::aid-hyp949>3.0.co;2-g
Subject(s) - evaporation , environmental science , water content , potential evaporation , scale (ratio) , moisture , atmospheric sciences , distribution (mathematics) , soil science , geology , meteorology , mathematics , geography , geotechnical engineering , mathematical analysis , cartography
Unresolved heterogeneity in a numerical simulation has a significant impact on the hydrological land surface processes, and the areally averaged quantities do not give the actual values of different 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 effect 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 specific humidity. The effect of the soil moisture distribution is significantly larger than that of the temperature distribution. Normal and uniform distributions with the same mean value and variance of the soil moisture have different effects on the area representative evaporation and the difference between the two reaches some 10%. Copyright © 2000 John Wiley & Sons, Ltd.