R - Copernicus.org

New tool for CO2 flux partitioning
with soil chamber flux implementation
as a solution for site in topographically
complex terrain
Šigut, L., Mammarella, I., Kolari, P.,
Dařenová, E., Novosadová, K., Pietras, J.,
Pokorný, R., Sedlák, P., Mauder, M.
Eddy covariance
• Fluxes of matter and energy in halfhour resolution
• Annual sum of NEE – the most important product
• Separation of NEE into GPP and Reco by simple models
• Light response curve (LRC)
• Temperature response curve (TRC)
MR05 (Reichstein et al., 2005)
Nighttime based Reco estim.; temperature response curve (TRC) fitting
GL10 (Lasslop et al., 2010)
Daytime based Reco estim.; TRC + light response curve (LRC) fitting
– only Reco temperature sensitivity from nighttime data
Both of these are accesible online
R script (here proposed new tool)
Combined nighttime and daytime Reco estim.; TRC + LRC fitting
Iterative TRC and LRC fitting
• Proper seasonality removal is really important
– changing time window size according to data coverage
– respiration sensitivity to temperature: 10 °C range
– light response curve: PAR range meeting requirements
(for alpha 150 µmol m-2 s-1, Amax 500 µmol m-2 s-1)
Basic assumptions
• Homogenous vegetation
• Flat terrain
Bílý Kříž
• Beskydy Mts., Czech republic
(877 m a.s.l., avg T=6.7 ± 1.1 °C)
• Norway Spruce monoculture
• 13° slope – advection
• Complex windflows, decoupling
Biotic CO2 flux
• Biotic ≠ measured CO2 flux
• Mainly nighttime problems
– Reco affected
• u*-filtering – standard
• Cannot be used for the site
Guan et al. 2006
Not filtered
NEP = GPP - Reco
Rsoil =
% ∙ Reco
Raich a Schlesinger, 1992: Rsoil = 40 – 80 % of Reco
Kolari et al., 2009
• Measurements only during growing season (May-Oct)
1) keep nighttime eddy covariance data outside GS
Rsoil =
• Measurements only during growing season (May-Oct)
2) use chamber based estimates outside of GS
the longest GS
LAI increase
Rsoil =
R script
• Seasonality removal should get more attention
• R script for flux partitioning produces defensible NEP
Complex site
• Single value of Rsoil/Reco ratio not valid for all years
• Lack of chamber measurement outside GS is probably
causing Reco under- (1)/overestimation (2) in selected
• Interanual changes in stand density, LAI and GS length
explain the best the observed NEP pattern
• University of Ostrava: OU SGS20/PřF/2014
• Global Change Research Centre AS CR, v. v. i.
CZ.1.05/1.1.00/02.0073, CZ.1.07/2.4.00/31.0056
• University of Helsinki
• MICMoR graduate programme
• Bionetwork
Thank you for your

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