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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},
}