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Abstract:
Three independent surface soil moisture datasets
for the period 1979-87 are compared:
(1) global retrievals from the Scanning Multichannel
Microwave Radiometer (SMMR),
(2) global soil moisture derived from observed meteorological forcing
using the NASA Catchment land surface model, and
(3) ground-based measurements in Eurasia and North America
from the Global Soil Moisture Data Bank.
Time average soil moisture fields from the satellite and the model
largely agree in the global patterns of wet and dry regions.
Moreover, the time series and anomaly time series of monthly mean
satellite and model soil moisture are well correlated in the
transition regions between wet and dry climates
where land initialization may be important for seasonal
climate prediction.
However, the magnitudes of
time average soil moisture and soil moisture variability
are markedly different between the datasets in many locations.
Absolute soil moisture values from the satellite and the model
are very different, and neither agrees better with ground data,
implying that a ``correct'' soil moisture climatology cannot
be identified with confidence from the available global data.
The discrepancies between the datasets point to a need for
bias estimation and correction or rescaling before satellite soil
moisture can be assimilated into land surface models.