Seasonal variations in radiation and energy balance in a deciduous broad-leaved forest |
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Authors: | Ho-Taek Park Shigeaki Hattori Takafumi Tanaka Gyung-Soo Cha |
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Affiliation: | (1) School of Bioagricultural Sciences, Nagoya University, 464-0814 Nagoya, Japan;(2) Department of Forestry, College of Agriculture, Chonnam National University, 500-757 Kwangju, Korea |
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Abstract: | This study was conducted to document the effects of canopy change on radiation and energy balances in a deciduous broad-leaved forest. Global solar radiation was highly variable with a maximum close to 28.7 MJ m−2 day−1 and a minimum of about 0.7 MJ m−2 day−1. The high daily variation of net radiation was the result of the frequency and duration of rainfall. The mean annual albedo in this study site was 0.126. Seasonal variation of albedo was characterized by steadily decreasing values with leaf-fall, but at the time when new leaves sprouted the trend did turn upwards. The mean annual radiation efficiency at this study site was 0.564, and the seasonal variation of the radiation efficiency was dependent upon the net long-wave radiation rather than albedo. This study also illustrated the seasonal variation of the proportion of the actual evaporation to the equilibrium evaporation as a means for estimating the latent heat flux from forest using the equilibrium evaporation model. Seasonal variation of the proportion of the actual evaporation to the equilibrium evaporation reflected the physiological and productive activities of trees. Latent heat flux dominated the energy balance and, in particular, reached about 96% of net radiation in July. |
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Keywords: | deciduous broad-leaved forest equilibrium evaporation model net radiation radiation and energy balances |
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