|Rebmann, C; Göckede, M; Foken, T; Aubinet, M; Aurela, M; Berbigier, P; Bernhofer, C; Buchmann, N; Carrara, A; Cescatti, A; Ceulemans, R; Clement, R; Elbers, JA; Granier, A; Grünwald, T; Guyon, D; Havránkova, K; Heinesch, B; Knohl, A; Laurila, T; Longdoz, B; Marcolla, B; Markkanen, T; Miglietta, F; Moncrieff, JB; Montagnani, L; Moors, E; Nardino, M; Ourcival, J-M; Rambal, S; Rannik, Ü; Rotenberg, E; Sedlak, P; Unterhuber, G; Vesala, T; Yakir, D: Quality analysis applied on eddy covariance measurements at complex forest sites using footprint modelling, Theoretical and Applied Climatology, 80, 121-141 (2005)|
Measuring turbulent fluxes with the eddy covariance method has become a widely accepted and powerful tool for the determination of long term data sets for the exchange of momentum, sensible and latent heat, and trace gases such as CO2 between the atmosphere and the underlying surface. Several flux networks developed continuous measurements above complex terrain, e.g. AmeriFlux and EUROFLUX, with a strong focus on the net exchange of CO2 between the atmosphere and the underlying surface. Under many conditions the basic assumptions for the eddy covariance method in its simplified form, such as stationarity of the flow, and homogeneity of the surface and fully developed turbulence of the flow field, are not fulfilled. To deal with non-ideal conditions which are common at many FLUXNET sites, quality tests have been developed to check if these basic theoretical assumptions are valid. In the framework of the CARBOEUROFLUX project, we combined quality tests described by Foken and Wichura (1996) with the analytical footprint model of Schmid (1997). The aim was to identify suitable wind sectors and meteorological conditions for flux measurements. These tools were used on data of 18 participating sites. Quality tests were applied on the fluxes of momentum, sensible and latent heat, and on the CO2 flux, respectively. The influence of the topography on the vertical wind component was also checked. At many sites the landuse around the flux towers is not homogeneous or the fetch may not be large enough. So the relative contribution of the landuse type intended to be measured was also investigated. Thus the developed tool allows comparative investigations of the measured turbulent fluxes at different sites if using the same technique and algorithms for the determination of the fluxes as well as analyses of potential problems caused by the influences of the surrounding landuse patterns.
|Fr. 2022-07-01 now|
3. Bayerische Biodiversitätstage in Bayern 2022
Postponed to WS 22/23: Preserving ecosystem services and biodiversity on agricultural land
Der Süden Neuseelands – Ursprüngliche Ökosysteme und ihre Bedrohung
Führung | "Mäusedorn und Katzenschwanz: Katzen und Botanik"
Ausstellungseröffnung | "Natur und Kunst" - Malerei und Graphik von Christel Gollner