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Characteristics of the heat balance above the canopies of evergreen and deciduous forests during the snowy season
Author(s) -
Ohta Takeshi,
Suzuki Kazuyoshi,
Kodama Yuji,
Kubota Jumpei,
Kominami Yuji,
Nakai Yuichiro
Publication year - 1999
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(199910)13:14/15<2383::aid-hyp872>3.0.co;2-s
Subject(s) - deciduous , evergreen , sensible heat , environmental science , canopy , atmospheric sciences , tree canopy , temperate deciduous forest , shortwave radiation , evergreen forest , ecology , geology , radiation , biology , physics , quantum mechanics
Heat and water exchange in forest areas constitutes one of the most important hydro‐meteorological systems. In this study, the energy balances above three forests were measured during winter. Two were evergreen conifer forests and the third was a leafless deciduous forest. From this study, we gained the following new insights: there were no significant differences between the magnitudes of the net all‐wave radiation and sensible heat, and the ratio of sensible heat to net all‐wave radiation between the three experimental forests, despite the marked differences in canopy conditions. The net short‐wave radiation was larger above the evergreen forests than above the deciduous forest, because of the low albedo above the evergreen forest. The converse was true, however, for net long‐wave radiation, especially in the daytime. This was due to the difference in the upward long‐wave radiation, because the deciduous forest canopy was quite sparse and some of the long‐wave radiation emitted from the snow surface reached the atmosphere through the canopy. There was no clear difference in the net all‐wave radiation above the two types of canopy. Canopy conditions caused major differences in roughness length and zero plane displacement. In the deciduous forest, the zero plane displacement was small and the roughness length was large, while in the evergreen forest the opposite was true. In the deciduous forest, the area in contact with the atmosphere increased because of the low position of the ‘active surface’, and the roughness length was also high. Consequently, the sensible heat from the deciduous forest did not differ from that of the evergreen forests. Copyright © 1999 John Wiley & Sons, Ltd.