Use of remotely sensed land use classification for a better evaluation of micrometeorological flux measurement sites |
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| Authors: | L M Reithmaier M Göckede T Markkanen A Knohl G Churkina C Rebmann N Buchmann T Foken |
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| Institution: | (1) Department of Micrometeorology, University of Bayreuth, Germany;(2) Department of Physical Sciences, University of Helsinki, Finland;(3) Max-Planck Institute for Biogeochemistry, Jena, Germany;(4) Institute of Plant Sciences, ETH Zuerich, Switzerland |
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| Abstract: | Summary Long-term flux measurement sites are often characterized by a heterogeneous terrain, which disagrees with the fundamental
theoretical assumptions for eddy-covariance measurements. An evaluation procedure to assess the influence of terrain heterogeneity
on the data quality has been developed by G?ckede et al. (2004), which combines existing quality assessment tools for flux
measurements with analytic footprint modeling. In addition to micrometeorological input data, this approach requires information
defining the land use structure and the roughness of the surrounding terrain.
The aim of this study was to improve the footprint based site evaluation approach by using high-resolution land use maps derived
by Landsat ETM+ and ASTER satellite data. The influence of the grid resolution of the maps on the results was examined, and
four different roughness length classification schemes were tested. Due to numerical instabilities of the analytic footprint
routine, as an additional footprint model a Lagrangian stochastic footprint routine (Rannik et al., 2003) was employed. Application
of the approach on two German FLUXNET sites revealed only weak influence of the characteristics of the land use data when
the land use structure was homogeneous. For a more heterogeneous site, use of the more detailed land use maps derived by remote
sensing methods resulted in distinct differences indicating the potential of remote sensing for improving the flux measurement
site evaluation. |
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