000139210 001__ 139210
000139210 005__ 20230310131404.0
000139210 037__ $$aFZJ-2013-05213
000139210 041__ $$aEnglish
000139210 1001_ $$0P:(DE-Juel1)129461$$aGraf, Alexander$$b0$$eCorresponding author$$ufzj
000139210 1112_ $$a30th Conference on Agricultural and Forest Meteorology/First Conference on Atmospheric Biogeosciences$$cBoston$$d2012-05-29 - 2012-06-01$$wU.S.A.
000139210 245__ $$aA tunnel-shaped flow-through chamber for minimum disturbance net ecosystem flux measurements
000139210 260__ $$c2012
000139210 3367_ $$0PUB:(DE-HGF)6$$2PUB:(DE-HGF)$$aConference Presentation$$bconf$$mconf$$s1384768250_17439$$xOther
000139210 3367_ $$033$$2EndNote$$aConference Paper
000139210 3367_ $$2DataCite$$aOther
000139210 3367_ $$2ORCID$$aLECTURE_SPEECH
000139210 3367_ $$2DRIVER$$aconferenceObject
000139210 3367_ $$2BibTeX$$aINPROCEEDINGS
000139210 520__ $$aEddy covariance measurements are the method of choice to determine net land surface – atmosphere fluxes of energy and matter, but in some cases cannot be applied in a representative way. In particular, requirements on the measurement height and the principles underlying the fetch or footprint of the sensor inhibit straightforward application in small (<< 100 m upwind) ecosystems. Small chambers as used on the leaf and soil level, on the other hand, considerably disturb the ecosystem and require numerous repetitions in space, if robust area-average net fluxes are aimed at. Within the framework of a project also including the upscaling of chamber- and downscaling of micrometeorological measurements, we here present a third approach: A chamber with strengths and weaknesses that are expected to be in an intermediate range between traditional chamber and micrometeorological methods. In order to ensure comparability to micrometeorologically determined fluxes, the chamber was tested on three different fields of sufficient size against eddy covariance stations. The chamber is a flow-through type and covers a comparatively large (1.7 m²) ground surface. Measures to minimize ecosystem disturbance include a thin FEP foil ceiling, a wide in- and outlet, and ventilation at the order of magnitude of outside wind speed. Here, we focus on experiments with passive ventilation, where the in- and outlet are aligned into the mean wind and longitudinal matter advection is measured while suppressing any vertical and crosswind turbulent or advective flux. In order to comply with the small resulting concentration differences between in- and outlet, a differential closed-path CO2 and H2O analyzer is used. Comparisons to eddy covariance measurements show a good agreement and slight negative bias for evapotranspiration (latent heat flux), and a somewhat larger scatter and bias for CO2 flux. The scatter of the CO2 flux is hypothetically attributed to spatial variability between the footprint of both methods. The bias indicates a possible slight to intermediate underestimation of fluxes, depending on the hypothetical reasons of energy balance non-closure of the eddy covariance measurement. Possible reasons of such an underestimation are discussed, including remaining microclimate modifications as well as the longitudinal turbulent flux, and further tests of or modifications to the system are discussed.
000139210 536__ $$0G:(DE-HGF)POF2-246$$a246 - Modelling and Monitoring Terrestrial Systems: Methods and Technologies (POF2-246)$$cPOF2-246$$fPOF II$$x0
000139210 536__ $$0G:(GEPRIS)139819005$$aDFG project 139819005 - Links between local scale and catchment scale measurements and modelling of gas exchange processes over land surfaces (139819005)$$c139819005$$x1
000139210 7001_ $$0P:(DE-HGF)0$$avan de Boer, Anneke$$b1
000139210 7001_ $$0P:(DE-HGF)0$$aWerner, Julius$$b2
000139210 7001_ $$0P:(DE-HGF)0$$aLangensiepen, Mathias$$b3
000139210 7001_ $$0P:(DE-Juel1)144420$$aSchmidt, Marius$$b4$$ufzj
000139210 7001_ $$0P:(DE-HGF)0$$aSchüttemeyer, Dirk$$b5
000139210 7001_ $$0P:(DE-Juel1)129549$$aVereecken, Harry$$b6$$ufzj
000139210 8564_ $$uhttp://www.ametsoc.org/MEET/fainst/201230agforest.html
000139210 909CO $$ooai:juser.fz-juelich.de:139210$$pVDB
000139210 9101_ $$0I:(DE-588b)5008462-8$$6P:(DE-Juel1)129461$$aForschungszentrum Jülich GmbH$$b0$$kFZJ
000139210 9101_ $$0I:(DE-588b)5008462-8$$6P:(DE-Juel1)144420$$aForschungszentrum Jülich GmbH$$b4$$kFZJ
000139210 9101_ $$0I:(DE-588b)5008462-8$$6P:(DE-Juel1)129549$$aForschungszentrum Jülich GmbH$$b6$$kFZJ
000139210 9131_ $$0G:(DE-HGF)POF2-246$$1G:(DE-HGF)POF2-240$$2G:(DE-HGF)POF2-200$$3G:(DE-HGF)POF2$$4G:(DE-HGF)POF$$aDE-HGF$$bErde und Umwelt$$lTerrestrische Umwelt$$vModelling and Monitoring Terrestrial Systems: Methods and Technologies$$x0
000139210 9141_ $$y2013
000139210 920__ $$lyes
000139210 9201_ $$0I:(DE-Juel1)IBG-3-20101118$$kIBG-3$$lAgrosphäre$$x0
000139210 980__ $$aconf
000139210 980__ $$aVDB
000139210 980__ $$aUNRESTRICTED
000139210 980__ $$aI:(DE-Juel1)IBG-3-20101118