Canopy Resistance and Estimation of Evapotranspiration above a Humid Cypress Forest
This study presented a two-year data set of sensible heat and water vapor fluxes above a humid subtropical montane Cypress forest, located at 1650 m a.s.l. in northeastern Taiwan. The focuses of this study were to investigate (1) the diurnal and seasonal variations of canopy resistance and fluxes of...
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| Language: | English |
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Wiley
2020-01-01
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| Series: | Advances in Meteorology |
| Online Access: | http://dx.doi.org/10.1155/2020/4232138 |
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| author | Bau-Show Lin Huimin Lei Ming-Che Hu Supattra Visessri Cheng-I Hsieh |
| author_facet | Bau-Show Lin Huimin Lei Ming-Che Hu Supattra Visessri Cheng-I Hsieh |
| author_sort | Bau-Show Lin |
| collection | DOAJ |
| description | This study presented a two-year data set of sensible heat and water vapor fluxes above a humid subtropical montane Cypress forest, located at 1650 m a.s.l. in northeastern Taiwan. The focuses of this study were to investigate (1) the diurnal and seasonal variations of canopy resistance and fluxes of sensible heat and water vapor above this forest; and (2) the mechanism of why a fixed canopy resistance could work when implementing the Penman–Monteith equation for diurnal hourly evapotranspiration estimation. Our results showed distinct seasonal variations in canopy resistance and water vapor flux, but on the contrary, the sensible heat flux did not change as much as the water vapor flux did with seasons. The seasonal variation patterns of the canopy resistance and water vapor flux were highly coupled with the meteorological factors. Also, the results demonstrated that a constant (fixed) canopy resistance was good enough for estimating the diurnal variation of evapotranspiration using Penman–Monteith equation. We observed a canopy resistance around 190 (s/m) for both the two warm seasons; and canopy resistances were around 670 and 320 (s/m) for the two cool seasons, respectively. In addition, our analytical analyses demonstrated that when the average canopy resistance is higher than 200 (s/m), the Penman–Monteith equation is less sensitive to the change of canopy resistance; hence, a fixed canopy resistance is suitable for the diurnal hourly evapotranspiration estimation. However, this is not the case when the average canopy resistance is less than 100 (s/m), and variable canopy resistances are needed. These two constraints (200 and 100) were obtained based on purely analytical analyses under a moderate meteorological condition (Rn = 600 W·m−2, RH = 60%, Ta = 20°C, U = 2 m·s−1) and a measurement height around two times of the canopy height. |
| format | Article |
| id | doaj-art-0dbb024cefbd4723ad4c729f3f9be859 |
| institution | Kabale University |
| issn | 1687-9309 1687-9317 |
| language | English |
| publishDate | 2020-01-01 |
| publisher | Wiley |
| record_format | Article |
| series | Advances in Meteorology |
| spelling | doaj-art-0dbb024cefbd4723ad4c729f3f9be8592025-08-20T03:54:24ZengWileyAdvances in Meteorology1687-93091687-93172020-01-01202010.1155/2020/42321384232138Canopy Resistance and Estimation of Evapotranspiration above a Humid Cypress ForestBau-Show Lin0Huimin Lei1Ming-Che Hu2Supattra Visessri3Cheng-I Hsieh4Department of Horticulture and Landscape Architecture, National Taiwan University, Taipei 10617, TaiwanDepartment of Hydraulic Engineering, Tsinghua University, Beijing 100084, ChinaDepartment of Bioenvironmental Systems Engineering, National Taiwan University, Taipei 10617, TaiwanDepartment of Water Resources Engineering, Chulalongkorn University, Bangkok 10330, ThailandDepartment of Bioenvironmental Systems Engineering, National Taiwan University, Taipei 10617, TaiwanThis study presented a two-year data set of sensible heat and water vapor fluxes above a humid subtropical montane Cypress forest, located at 1650 m a.s.l. in northeastern Taiwan. The focuses of this study were to investigate (1) the diurnal and seasonal variations of canopy resistance and fluxes of sensible heat and water vapor above this forest; and (2) the mechanism of why a fixed canopy resistance could work when implementing the Penman–Monteith equation for diurnal hourly evapotranspiration estimation. Our results showed distinct seasonal variations in canopy resistance and water vapor flux, but on the contrary, the sensible heat flux did not change as much as the water vapor flux did with seasons. The seasonal variation patterns of the canopy resistance and water vapor flux were highly coupled with the meteorological factors. Also, the results demonstrated that a constant (fixed) canopy resistance was good enough for estimating the diurnal variation of evapotranspiration using Penman–Monteith equation. We observed a canopy resistance around 190 (s/m) for both the two warm seasons; and canopy resistances were around 670 and 320 (s/m) for the two cool seasons, respectively. In addition, our analytical analyses demonstrated that when the average canopy resistance is higher than 200 (s/m), the Penman–Monteith equation is less sensitive to the change of canopy resistance; hence, a fixed canopy resistance is suitable for the diurnal hourly evapotranspiration estimation. However, this is not the case when the average canopy resistance is less than 100 (s/m), and variable canopy resistances are needed. These two constraints (200 and 100) were obtained based on purely analytical analyses under a moderate meteorological condition (Rn = 600 W·m−2, RH = 60%, Ta = 20°C, U = 2 m·s−1) and a measurement height around two times of the canopy height.http://dx.doi.org/10.1155/2020/4232138 |
| spellingShingle | Bau-Show Lin Huimin Lei Ming-Che Hu Supattra Visessri Cheng-I Hsieh Canopy Resistance and Estimation of Evapotranspiration above a Humid Cypress Forest Advances in Meteorology |
| title | Canopy Resistance and Estimation of Evapotranspiration above a Humid Cypress Forest |
| title_full | Canopy Resistance and Estimation of Evapotranspiration above a Humid Cypress Forest |
| title_fullStr | Canopy Resistance and Estimation of Evapotranspiration above a Humid Cypress Forest |
| title_full_unstemmed | Canopy Resistance and Estimation of Evapotranspiration above a Humid Cypress Forest |
| title_short | Canopy Resistance and Estimation of Evapotranspiration above a Humid Cypress Forest |
| title_sort | canopy resistance and estimation of evapotranspiration above a humid cypress forest |
| url | http://dx.doi.org/10.1155/2020/4232138 |
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