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@PHDTHESIS{Rtzer:810733,
author = {Rötzer, Kathrina},
title = {{S}tatistical analysis and combination of active and
passive microwave remote sensing methods for soil moisture
retrieval},
volume = {321},
school = {Universität Bonn},
type = {Dr.},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
reportid = {FZJ-2016-03325},
isbn = {978-3-95806-143-9},
series = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
Umwelt / Energy $\&$ Environment},
pages = {XIV, 112 S.},
year = {2016},
note = {Universität Bonn, Diss., 2016},
abstract = {Knowledge about soil moisture and its spatio-temporal
dynamics is essential for the improvement of climate and
hydrological modeling, including drought and flood
monitoring and forecasting, as well as weather forecasting
models. In recent years, several soil moisture products from
active and passive microwave remote sensing have become
available with high temporal resolution and global coverage.
However, for the improvement of a soil moisture product and
for its proper use in models or other applications,
validation and evaluation of its spatial and temporal
patterns are of great importance. In chapter 2 the Level 2
Soil Moisture and Ocean Salinity (SMOS) soil moisture
product and the Advanced Scatterometer (ASCAT) surface soil
moisture product are validated in the Rur and Erft
catchments in western Germany for the years 2010 to 2012
against a soil moisture reference created by a hydrological
model, which was calibrated by in situ observations.
Correlation with the modeled soil moisture reference results
in an overall correlation coefficient of 0.28 for the SMOS
product and 0.50 for ASCAT. While the correlation of both
products with the reference is highly dependent ontopography
and vegetation, SMOS is also strongly influenced by
radiofrequency interferences in the study area. Both
products exhibit dry biases as compared to the reference.
The bias of the SMOS product is constant in time, while the
ASCAT bias is more variable. For the investigation of spatio
temporal soil moisture patterns in the study area, a new
validation method based on the temporal stability analysis
is developed. Through investigation of mean relative
differences of soil moisture for every pixel the temporal
persistence of spatial patterns is analyzed. Results
indicate a lower temporal persistence for both SMOS and
ASCAT soil moisture products as compared to modeled soil
moisture. ASCAT soil moisture, converted to absolute values,
shows highest consistence of ranks and therefore most
similar spatio-temporal patterns with the soil moisture
reference, while the correlation of ranks of mean relative
differences is low for SMOS and relative ASCAT soil moisture
products. Chapter 3 investigates the spatial and temporal
behavior of the SMOS and ASCAT soil moisture products and
additionally of the ERA Interim product from a weather
forecast model reanalysis on global scale. Results show
similar temporal patterns of the soil moisture products, but
high impact of sensor and retrieval types and therefore
higher deviations in absolute soil moisture values. Results
are more variable for the spatial patterns of the soil
moisture products: While the global patterns are similar, a
ranking of mean relative differences reveals that ASCAT and
ERA Interim products show most similar spatial soil moisture
patterns, while ERA and SMOS products show least
similarities. Patterns are generally more similar between
the products in regions with low vegetation. [...]},
cin = {IBG-3},
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)11},
url = {https://juser.fz-juelich.de/record/810733},
}