Surface conductance for evapotranspiration of tropical forests: Calculations, variations, and controls

Zheng Hong Tan, Jun Fu Zhao, Guan Ze Wang, Meng Ping Chen, Lian Yan Yang, Chun Sheng He, Natalia Restrepo-Coupe, Shu Shi Peng, Xue Yan Liu, Humberto R. da Rocha, Yoshiko Kosugi, Takashi Hirano, Scott R. Saleska, Michael L. Goulden, Jiye Zeng, Fang Jun Ding, Fu Gao, Liang Song

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


Tropical forests are responsible for the evaporation and transpiration of large quantities of water into the atmosphere annually. Surface conductance (gs) is a poorly understood phenomenon that plays a central role in regulating this evapotranspiration. We studied the calculations, variations, and environmental factors controlling gs based on eddy flux measurements from 10 tropical forest sites that covered a wide range of water gradients across continents. We found that boundary layer conductance (gb) is comparable with aerodynamic conductance for momentum (gaM) and thus, it should not be ignored in estimations of total aerodynamic conductance for water vapor (gaV). Based on the findings, we have made some recommendations for gaM estimation both with and without measurements of turbulence. The seasonal variation of gs is low in humid sites but large in sites with a dry season. A value of 24.8 ± 13.8 mm s−1 was suggested for maximum surface conductance (gsmax) for tropical forests. Both water vapor deficit (D) and radiation (Q) play an important role in controlling gs. The model driven by both D and Q could capture the diurnal variations of gs well and could be implemented in large-scale models in future. We believe the findings of this study could contribute substantially to our understanding of tropical forest gs.

Original languageEnglish (US)
Pages (from-to)317-328
Number of pages12
JournalAgricultural and Forest Meteorology
StatePublished - Sep 15 2019


  • Boundary layer conductance
  • Energy imbalance correction
  • Jarvis stomata model
  • Maximum surface conductance
  • Penman–Monteith equation

ASJC Scopus subject areas

  • Forestry
  • Global and Planetary Change
  • Agronomy and Crop Science
  • Atmospheric Science


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