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Characterizing the multi–scale spatial structure of remotely sensed evapotranspiration with information theory
Brunsell, Nathaniel A.
Brunsell, Nathaniel A.
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Abstract
A more thorough understanding of the multi-scale
spatial structure of land surface heterogeneity will enhance
understanding of the relationships and feedbacks between
land surface conditions, mass and energy exchanges between
the surface and the atmosphere, and regional meteorological
and climatological conditions. The objectives of this
study were to (1) quantify which spatial scales are dominant
in determining the evapotranspiration flux between the surface
and the atmosphere and (2) to quantify how different
spatial scales of atmospheric and surface processes interact
for different stages of the phenological cycle. We used the
ALEXI/DisALEXI model for three days (DOY 181, 229 and
245) in 2002 over the Ft. Peck Ameriflux site to estimate
the latent heat flux from Landsat, MODIS and GOES satellites.
We then applied a multiresolution information theory
methodology to quantify these interactions across different
spatial scales and compared the dynamics across the different
sensors and different periods. We note several important
results: (1) spatial scaling characteristics vary with day,
but are usually consistent for a given sensor, but (2) different
sensors give different scalings, and (3) the different sensors
exhibit different scaling relationships with driving variables
such as fractional vegetation and near surface soil moisture.
In addition, we note that while the dominant length scale of
the vegetation index remains relatively constant across the
dates, the contribution of the vegetation index to the derived
latent heat flux varies with time. We also note that length
scales determined from MODIS are consistently larger than
those determined from Landsat, even at scales that should
be detectable by MODIS. This may imply an inability of the
MODIS sensor to accurately determine the fine scale spatial structure of the land surface. These results aid in identifying
the dominant cross-scale nature of local to regional
biosphere-atmosphere interactions.
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Date
2011-08-22
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European Geosciences Union
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Brunsell, N. A. and M. C. Anderson: 2011, Characterizing the multi-scale spatial structure of remotely sensed evapotranspiration with information theory. Biogeosciences, 8, 2269-2280. http://dx.doi.org/ 10.5194/bg-8-2269-2011