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Observational evidence on the effects of clouds and aerosols on net ecosystem exchange and evapotranspiration
Author(s) -
Wang Kaicun,
Dickinson Robert E.,
Liang Shunlin
Publication year - 2008
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2008gl034167
Subject(s) - environmental science , atmospheric sciences , cloud fraction , eddy covariance , evapotranspiration , aerosol , meteorology , physics , ecosystem , cloud computing , cloud cover , ecology , biology , computer science , operating system
Clouds and aerosols control variations in the ratio of diffuse to total incident solar radiation ( R d / R s ) and so determine to a large extent variations in both Light‐Use Efficiency ( LUE ) and in the Evaporative Fraction ( EF ). Five years (2002–2007) of continuous ground measurements collected at twenty‐three sites in the U.S. were analyzed to quantify this effect. Our results show that LUE is 19.4% and 203% larger for patchy clouds, and thick clouds than those for clear skies while LUE is about −6% for aerosols or thin clouds than those for clear skies. EF is 15.4%, 17.9% and 23.2% larger for aerosols or thin clouds, patchy clouds, and thick clouds than those for the clear sky when Eddy Covariance ( ECOR ) data are used, respectively. The values are 9.0%, 11.3% and 23.3% when Energy Balance Bowen Ratio ( EBBR ) data are used. This is the first systematic observational study on effects of R d / R s on EF and further study is needed.