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I. Mladenova, V. Lakshmi, J. Walker, R. Panciera, W. Wagner, M. Doubkova:
"Validation of the ASAR Global Monitoring mode soil moisture product using the NAFE`05 data set";
IEEE Transactions on Geoscience and Remote Sensing, 48 (2010), 6; 2498 - 2508.

The Advanced Synthetic Aperture Radar (ASAR)
Global Monitoring (GM) mode offers an opportunity for global
soil moisture (SM) monitoring at much finer spatial resolution
than that provided by the currently operational Advanced Microwave
Scanning Radiometer for the Earth Observing System and
future planned missions such as Soil Moisture and Ocean Salinity
and Soil Moisture Active Passive. Considering the difficulties in
modeling the complex soil-vegetation scattering mechanisms and
the great need of ancillary data for microwave backscatter SM
inversion, algorithms based on temporal change are currently the
best method to examine SM variability. This paper evaluates the
spatial sensitivity of the ASAR GM surface SM product derived
using the temporal change detection methodology developed by
the Vienna University of Technology. This evaluation is made for
an area in southeastern Australia using data from the National
Airborne Field Experiment 2005. The spatial evaluation is made
using three different types of SMdata (station, field, and airborne)
across several different scales (1-25 km). Results confirmed the
expected better agreement when using point (Rstation = 0.75)
data as compared to spatial (RPLMR, 1km = 0.4) data. While
the aircraft-ASAR GM correlation values at 1-km resolution
were low, they significantly improved when averaged to 5 km
(RPLMR, 5km = 0.67) or coarser. Consequently, this assessment
shows the ASAR GM potential for monitoring SM when averaged
to a spatial resolution of at least 5 km.