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It goes both ways: measurements of simultaneous evapotranspiration and fog droplet deposition at a montane cloud forest
Author(s) -
Beiderwieden E.,
Wolff V.,
Hsia Y.J.,
Klemm O.
Publication year - 2008
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/hyp.7017
Subject(s) - evapotranspiration , eddy covariance , sensible heat , bowen ratio , latent heat , environmental science , cloud forest , atmospheric sciences , deposition (geology) , water vapor , noon , humidity , flux (metallurgy) , hydrology (agriculture) , meteorology , montane ecology , chemistry , geography , physics , geology , ecosystem , ecology , paleontology , geotechnical engineering , organic chemistry , sediment , biology
Fluxes of latent heat, sensible heat, and water vapor, including turbulent deposition of fog droplets, were measured for two months in autumn 2005 within a subtropical montane cypress forest in Taiwan. The goal of the study was to determine whether significant evapotranspiration can occur during foggy conditions. Water vapor fluxes, Q W , as determined with the Bowen Ratio method, were compared to those simultaneously measured with the eddy covariance method. The median Bowen Ratio was 1.06, and the median Q W flux was 5 · 2 × 10 −5 kg m −2 s −1 . The vertical gradients of temperature and specific humidity over the forest, Δ T and Δ q , peaked around noon during days without fog, and were reduced during foggy conditions. For 66% of the data points, Δ T and Δ q were negative, corresponding to positive (upward) fluxes of sensible heat Q H and latent heat Q E . A Monte Carlo simulation proved that statistically significant evapotranspiration rates, i.e., upward water vapor fluxes, occurred during fog. At the same time, deposition fluxes of fog droplets occurred. Our results show that even during fog events, significant evapotranspiration may occur. Copyright © 2008 John Wiley & Sons, Ltd.