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@ARTICLE{Graf:15985,
      author       = {Graf, A. and Prolingheuer, N. and Schickling, A. and
                      Schmidt, M. and Schneider, K. and Schüttemeyer, D. and
                      Herbst, M. and Huisman, J.A. and Weihermüller, L. and
                      Scharnagl, B. and Steenpass, C. and Harms, R. and Vereecken,
                      H.},
      title        = {{T}emporal {D}ownscaling of {S}oil {C}arbon {D}ioxide
                      {E}fflux {M}easurements {B}ased on {T}ime-{S}table {S}patial
                      {P}atterns},
      journal      = {Vadose zone journal},
      volume       = {10},
      issn         = {1539-1663},
      address      = {Madison, Wis.},
      publisher    = {SSSA},
      reportid     = {PreJuSER-15985},
      pages        = {239 - 251},
      year         = {2011},
      note         = {A. Graf and D. Schuttemeyer gratefully acknowledge
                      financial support by the Deutsche Forschungsgemeinschaft
                      (DFG) project "Links between local scale and catchment scale
                      measurements and modelling of gas exchange processes over
                      land surfaces." N. Prolingheuer, A. Schickling, M. Herbst,
                      J.A. Huisman, B. Scharnagl, C. Steenpass, and H. Vereecken
                      gratefully acknowledge financial support by the
                      Transregional collaborative research center (SFB/TR) 32
                      "Patterns in Soil-Vegetation-Atmosphere Systems: Monitoring,
                      Modelling, and Data Assimilation" funded by the DFG.
                      Instrument funding was provided by the Helmholtz project
                      FLOWatch. We would like to thank Morton Canty and Carsten
                      Montzka for processing the geodata condensed in the middle
                      part of Fig. 1, as well as Friederike Beulshausen, Marta
                      Burmistrow, Sina Egerer, Martin Hank, Christian Koyama,
                      Hendrik Merbitz, Jan Rass, Anne Rosenkranz and Paul Wagner
                      for additional help with the labor-intensive manual chamber
                      measurements.},
      abstract     = {Soil CO2 efflux at a field site is often computed as the
                      average of successive chamber measurements at several points
                      to overcome the effects of spatial variability and
                      microclimatic disturbances. As a consequence, the resulting
                      data set has a coarser resolution in space (one average per
                      site) and time than the raw data set. The deviations between
                      raw measurements and the field average may provide
                      additional insights, however, if they can be decomposed into
                      a time-stable part, characterizing the spatial pattern of
                      emission strengths, and a dynamic part, characterizing rapid
                      changes in soil CO2 efflux. We evaluated data from several
                      measurement campaigns in an agricultural landscape. First,
                      we determined the persistence of spatial CO2 efflux patterns
                      and found that >= $50\%$ of spatial variance was stable for
                      at least 1 d in all examined crop and field types. For
                      fields where vegetation and gradients in soil properties
                      determined the spatial variation in CO2 efflux, some
                      correlation was still found after 10 d. In a next step, we
                      removed the time-stable patterns from the raw time series.
                      The resulting estimate of instantaneous area-average soil
                      respiration closely resembled the conventional
                      spatiotemporal field average on days without rapid changes
                      in meteorologic conditions. On days with fluctuations of
                      radiation and temperature, in contrast, soil respiration
                      reacted on a time scale from instantaneous to about 1 h.
                      Based on a discussion of potential mechanisms underlying
                      these reactions for a wheat (Triticum aestivum L.) and a
                      sugarbeet (Beta vulgaris L. ssp. vulgaris) stand, we suggest
                      that the proposed downscaling methodology, in combination
                      with existing decomposition techniques, may help to examine
                      the short-term dependence of heterotrophic and root
                      respiration on radiation, temperature, and rain.},
      keywords     = {J (WoSType)},
      cin          = {IBG-3},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IBG-3-20101118},
      pnm          = {Terrestrische Umwelt},
      pid          = {G:(DE-Juel1)FUEK407},
      shelfmark    = {Environmental Sciences / Soil Science / Water Resources},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000287573300020},
      doi          = {10.2136/vzj2009.0152},
      url          = {https://juser.fz-juelich.de/record/15985},
}