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@ARTICLE{Rotzer:834972,
author = {Rotzer, Kathrina and Montzka, Carsten and Entekhabi, Dara
and Konings, Alexandra G. and McColl, Kaighin A. and Piles,
Maria and Vereecken, Harry},
title = {{R}elationship {B}etween {V}egetation {M}icrowave {O}ptical
{D}epth and {C}ross-{P}olarized {B}ackscatter {F}rom
{M}ultiyear {A}quarius {O}bservations},
journal = {IEEE journal of selected topics in applied earth
observations and remote sensing},
volume = {10},
number = {10},
issn = {2151-1535},
address = {New York, NY},
publisher = {IEEE},
reportid = {FZJ-2017-04842},
pages = {4493 - 4503},
year = {2017},
abstract = {Soil moisture retrieval algorithms based on passive
microwave remote sensing observations need to account for
vegetation attenuation and emission, which is generally
parameterized as vegetation optical depth (VOD). This
multisensor study tests a new method to retrieve VOD from
cross-polarized radar backscattering coefficients. Three
years of Aquarius/SAC-D data were used to establish a
relationship between the cross-polarized backscattering
coefficient σHV and VOD derived from a multitemporal
passive dual-channel algorithm (VODMT). The dependence of
the correspondence is analyzed for different land use
classes. There are no systematic differences in the slope
for woody versus nonwoody vegetation, resulting in a strong
correlation $(80\%$ explained-variance) and a global linear
relationship when all classes are combined. The relationship
is stable over the years of observations. The comparison of
the Aquarius-derived VODMT to Soil Moisture and Ocean
Salinity's multi-angular VOD estimates shows similar spatial
patterns and temporal behavior, evident in high
correlations. However, VODMT has considerably higher mean
values, but lower dynamic range globally. Most of the
differences can be attributed to differences in instrument
sampling. The main result of this study, a relationship
between backscatter and VOD, will permit high-resolution
mapping of VOD with synthetic aperture radar measurements.
These maps allow future studies of scaling and heterogeneity
effects of vegetation on soil moisture retrieval at the
coarser scales of land microwave radiometry. The study shows
that VOD based on passive measurements and predicted by
active measurements are comparable globally and that the
breakdown by land cover classification does not affect the
relationship appreciably.},
cin = {IBG-3},
ddc = {520},
cid = {I:(DE-Juel1)IBG-3-20101118},
pnm = {255 - Terrestrial Systems: From Observation to Prediction
(POF3-255)},
pid = {G:(DE-HGF)POF3-255},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000412626500022},
doi = {10.1109/JSTARS.2017.2716638},
url = {https://juser.fz-juelich.de/record/834972},
}