TY - JOUR
T1 - Estimating nocturnal ecosystem respiration from the vertical turbulent flux and change in storage of CO2
AU - van Gorsel, Eva
AU - Delpierre, Nicolas
AU - Leuning, Ray
AU - Black, Andy
AU - Munger, J. William
AU - Wofsy, Steven
AU - Aubinet, Marc
AU - Feigenwinter, Christian
AU - Beringer, Jason
AU - Bonal, Damien
AU - Chen, Baozhang
AU - Chen, Jiquan
AU - Clement, Robert
AU - Davis, Kenneth J.
AU - Desai, Ankur R.
AU - Dragoni, Danilo
AU - Etzold, Sophia
AU - Grünwald, Thomas
AU - Gu, Lianhong
AU - Heinesch, Bernhard
AU - Hutyra, Lucy R.
AU - Jans, Wilma W.P.
AU - Kutsch, Werner
AU - Law, B. E.
AU - Leclerc, Monique Y.
AU - Mammarella, Ivan
AU - Montagnani, Leonardo
AU - Noormets, Asko
AU - Rebmann, Corinna
AU - Wharton, Sonia
N1 - Funding Information:
Acknowledgement is given to the many people involved in construction, maintenance and expansion of the flux stations as well as in data transfer, processing, control and archiving and to everyone involved in getting the LaThuile data set and synthesis paper writing teams together. Eva van Gorsel acknowledges the stimulating discussions with John Finnigan, Ian Harman and Stephen Belcher. This work was supported in part by a grant from the Australian Greenhouse Office (1999–2007) through the Australian Climate Change Science Program and its predecessors. We thank all site investigators, their funding agencies and the various regional flux networks (AmeriFlux, CarboEurope-IP, Fluxnet-Canada, NECC, OzFlux) that contributed to this study. B.E. Law was supported by the AmeriFlux Science Team Research grant (U.S. Department of Energy, Terrestrial Carbon program. Award #DE-FG02-04ER63911), Monique Leclerc acknowledges support by the U.S. Dept. of Energy, Office of Science (Grant no. ER64321) Research at the MM site was supported by the Office of Science (BER), U.S. Department of Energy, Grant No. DE-FG02-07ER64371. We acknowledge funding of the IMECC I3 EU project, ICOS EU project by the Academy of Finland. We also acknowledge support and suggestions of two anonymous reviewers.
PY - 2009/11/3
Y1 - 2009/11/3
N2 - Micrometeorological measurements of nighttime ecosystem respiration can be systematically biased when stable atmospheric conditions lead to drainage flows associated with decoupling of air flow above and within plant canopies. The associated horizontal and vertical advective fluxes cannot be measured using instrumentation on the single towers typically used at micrometeorological sites. A common approach to minimize bias is to use a threshold in friction velocity, u*, to exclude periods when advection is assumed to be important, but this is problematic in situations when in-canopy flows are decoupled from the flow above. Using data from 25 flux stations in a wide variety of forest ecosystems globally, we examine the generality of a novel approach to estimating nocturnal respiration developed by van Gorsel et al. (van Gorsel, E., Leuning, R., Cleugh, H.A., Keith, H., Suni, T., 2007. Nocturnal carbon efflux: reconciliation of eddy covariance and chamber measurements using an alternative to the u*-threshold filtering technique. Tellus 59B, 397-403, Tellus, 59B, 307-403). The approach is based on the assumption that advection is small relative to the vertical turbulent flux (FC) and change in storage (FS) of CO2 in the few hours after sundown. The sum of FC and FS reach a maximum during this period which is used to derive a temperature response function for ecosystem respiration. Measured hourly soil temperatures are then used with this function to estimate respiration RRmax. The new approach yielded excellent agreement with (1) independent measurements using respiration chambers, (2) with estimates using ecosystem light-response curves of Fc + Fs extrapolated to zero light, RLRC, and (3) with a detailed process-based forest ecosystem model, Rcast. At most sites respiration rates estimated using the u*-filter, Rust, were smaller than RRmax and RLRC. Agreement of our approach with independent measurements indicates that RRmax provides an excellent estimate of nighttime ecosystem respiration.
AB - Micrometeorological measurements of nighttime ecosystem respiration can be systematically biased when stable atmospheric conditions lead to drainage flows associated with decoupling of air flow above and within plant canopies. The associated horizontal and vertical advective fluxes cannot be measured using instrumentation on the single towers typically used at micrometeorological sites. A common approach to minimize bias is to use a threshold in friction velocity, u*, to exclude periods when advection is assumed to be important, but this is problematic in situations when in-canopy flows are decoupled from the flow above. Using data from 25 flux stations in a wide variety of forest ecosystems globally, we examine the generality of a novel approach to estimating nocturnal respiration developed by van Gorsel et al. (van Gorsel, E., Leuning, R., Cleugh, H.A., Keith, H., Suni, T., 2007. Nocturnal carbon efflux: reconciliation of eddy covariance and chamber measurements using an alternative to the u*-threshold filtering technique. Tellus 59B, 397-403, Tellus, 59B, 307-403). The approach is based on the assumption that advection is small relative to the vertical turbulent flux (FC) and change in storage (FS) of CO2 in the few hours after sundown. The sum of FC and FS reach a maximum during this period which is used to derive a temperature response function for ecosystem respiration. Measured hourly soil temperatures are then used with this function to estimate respiration RRmax. The new approach yielded excellent agreement with (1) independent measurements using respiration chambers, (2) with estimates using ecosystem light-response curves of Fc + Fs extrapolated to zero light, RLRC, and (3) with a detailed process-based forest ecosystem model, Rcast. At most sites respiration rates estimated using the u*-filter, Rust, were smaller than RRmax and RLRC. Agreement of our approach with independent measurements indicates that RRmax provides an excellent estimate of nighttime ecosystem respiration.
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U2 - 10.1016/j.agrformet.2009.06.020
DO - 10.1016/j.agrformet.2009.06.020
M3 - Article
AN - SCOPUS:69849084044
VL - 149
SP - 1919
EP - 1930
JO - Agricultural and Forest Meteorology
JF - Agricultural and Forest Meteorology
SN - 0168-1923
IS - 11
ER -