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Energy partitioning between latent and sensible heat flux during the warm season at FLUXNET sites
Author(s) -
Wilson Kell B.,
Baldocchi Dennis D.,
Aubinet Marc,
Berbigier Paul,
Bernhofer Christian,
Dolman Han,
Falge Eva,
Field Chris,
Goldstein Allen,
Granier Andre,
Grelle Achim,
Halldor Thorgeirsson,
Hollinger Dave,
Katul Gabriel,
Law B. E.,
Lindroth Anders,
Meyers Tilden,
Moncrieff John,
Monson Russ,
Oechel Walter,
Tenhunen John,
Valentini Riccardo,
Verma Shashi,
Vesala Timo,
Wofsy Steve
Publication year - 2002
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2001wr000989
Subject(s) - fluxnet , eddy covariance , vapour pressure deficit , latent heat , environmental science , sensible heat , atmospheric sciences , bowen ratio , flux (metallurgy) , mediterranean climate , growing season , biometeorology , climatology , canopy , ecosystem , geography , ecology , transpiration , chemistry , photosynthesis , meteorology , geology , botany , biology , organic chemistry
The warm season (mid‐June through late August) partitioning between sensible ( H ) and latent ( LE ) heat flux, or the Bowen ratio (β = H / LE ), was investigated at 27 sites over 66 site years within the international network of eddy covariance sites (FLUXNET). Variability in β across ecosystems and climates was analyzed by quantifying general climatic and surface characteristics that control flux partitioning. The climatic control on β was quantified using the climatological resistance ( R i ), which is proportional to the ratio of vapor pressure deficit (difference between saturation vapor pressure and atmospheric vapor pressure) to net radiation (large values of R i decrease β). The control of flux partitioning by the vegetation and underlying surface was quantified by computing the surface resistance to water vapor transport ( R c , with large values tending to increase β). There was a considerable range in flux partitioning characteristics ( R c , R i and β) among sites, but it was possible to define some general differences between vegetation types and climates. Deciduous forest sites and the agricultural site had the lowest values of R c and β (0.25–0.50). Coniferous forests typically had a larger R c and higher β (typically between 0.50 and 1.00 but also much larger). However, there was notable variability in R c and R i between coniferous site years, most notably differences between oceanic and continental climates and sites with a distinct dry summer season (Mediterranean climate). Sites with Mediterranean climates generally had the highest net radiation, R c , R i , and β. There was considerable variability in β between grassland site years, primarily the result of interannual differences in soil water content and R c .