Evaluation
of the difference between annual net CO2 ecosystem exchanges (NEE)
from the open- and the closed-path data is important for site intercomparison
studies. However, long-term measurements of NEE using both systems have been
limited. We report the comparison of eddy CO2 fluxes measured with
open- and closed path systems for three years from 2001 through 2003. The
annual GPP estimated from closed-path data was 8–10% less negative than that
from the open-path data, whereas the annual RE was 11–16% more positive for
closed-path data. Consequently, the annual NEE from the closed-path data was
less negative by 301–333 gC m-2 y-1. The bias of NEE
between two systems is large and an extremely important issue. Ecophysiological
approaches are needed to validate of the eddy covariance technique.
Author: R. Hirata, T. Hirano, N. Saigusa, Y. Fujinuma, et al (hirata dot ryuichi at nies dot go dot jp)
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