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New tool for CO 2 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. Introduction.
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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.
Introduction Eddy covariance • Fluxesofmatter and energy in halfhourresolution • Annual sum of NEE – the most importantproduct • Separationof NEE into GPP and Recoby simplemodels
Simplemodels NEE Reco GPP • Light response curve (LRC) • Temperature response curve (TRC)
Methods • MR05 (Reichstein et al., 2005) • NighttimebasedRecoestim.; temperature response curve (TRC) fitting • GL10 (Lasslop et al., 2010) • DaytimebasedRecoestim.; TRC + lightresponse curve(LRC) fitting • onlyRecotemperature sensitivity fromnighttime data • Bothof these are accesible online • (http://www.bgc-jena.mpg.de/~MDIwork/eddyproc) • R script (hereproposednewtool) • Combinednighttime and daytimeRecoestim.; TRC + LRC fitting
Fine resolutionfitting Iterative TRC and LRC fitting
Lessonslearned • Proper seasonalityremovalisreallyimportant • changingtimewindowsizeaccording to data coverage • respiration sensitivity to temperature: 10 °C range • light response curve: PAR range meeting requirements(foralpha 150 µmol m-2 s-1, Amax 500 µmol m-2 s-1)
Complexsite Basic assumptions Advection • Homogenousvegetation • Flatterrain Bílý Kříž • Beskydy Mts., Czech republic(877 m a.s.l., avgT=6.7 ± 1.1 °C) • NorwaySprucemonoculture • 13° slope– advection • Complexwindflows, decoupling
Estimationof NEP Biotic CO2 flux • Biotic ≠ measured CO2 flux • Mainlynighttimeproblems • Recoaffected • u*-filtering– standard • Cannotbeusedforthesite Guan et al. 2006
Not filtered NEP = GPP - Reco NPP = GPP - RA u*-filtered
Chambersupscaling ? Rsoil = % Reco Raicha Schlesinger, 1992: Rsoil = 40 – 80 % ofReco Kolari et al., 2009
Measurementsonlyduringgrowingseason (May-Oct) • keepnighttimeeddycovariance data outside GS Rsoil = x%Reco
Measurementsonlyduringgrowingseason (May-Oct) • use chamberbasedestimatesoutsideof GS windfall windfall Rsoil = x%Reco thelongest GS LAI increase
Conclusion R script • Seasonalityremovalshouldget more attention • R scriptfor flux partitioningproducesdefensible NEP Complexsite • Single value of Rsoil/Reco ratio not valid for all years • Lack of chamber measurement outside GS is probably causing Recounder- (1)/overestimation (2) in selectedapproaches • Interanualchanges in standdensity, LAI and GS lengthexplainthebesttheobserved NEP pattern
Acknowledgement • University of Ostrava: OU SGS20/PřF/2014 • GlobalChangeResearch Centre AS CR, v. v. i. CZ.1.05/1.1.00/02.0073, CZ.1.07/2.4.00/31.0056 • University ofHelsinki • MICMoRgraduateprogramme • Bionetwork