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R. De Jeu, R. Parinussa, Y. Liu, W. Dorigo, W. Wagner, K. Scipal, A.J. Dolman, B. Su:
"Trends and dynamics in long term satellite soil moisture data sets";
Talk: Earth Observation and Water Cycle Science Symposium, Frascati, Italy; 2009-11-18 - 2009-11-20; in: "ESA Special Publications SP-674", (2009), ISBN: 978-92-9221-238-4; 6 pages.

In this study we analysed the spatiotemporal behaviour
of soil moisture using data sets from different
microwave satellites. The main goal was to get a better
understanding on the impacts of climate and climate
change on the terrestrial hydrology.
As a first step, a continuous product was developed for
mainland Australia by scaling percentiles of the
cumulative moisture distribution within each grid cell to
the percentiles of a reference sensor. The coefficient of
correlation and root mean squared error between
rescaled values and in situ observations generally
suggest good agreement. Using the merged data product
long term trends were analysed. North-western
Australia has experienced an increase in soil moisture
content, while the east and south-east experienced a
significant decrease in soil moisture over the 29 year
period. These trends can be explained by a long term
change in both the evaporation and precipitation.
As a second step, the impact of El Niño Southern
Oscillation (ENSO) on the soil moisture fields was
analysed over the US. This analysis revealed that interannual
variability of soil moisture of the western and
southern part of the US was strongly linked to ENSO.
These fields were found in both the active and passive
soil moisture products showing the importance of ocean
oscillation systems on the water distribution over land.
These two preliminary studies give us confidence in the
reliability of satellite soil moisture products and we
expect that the final merged dataset will enhance our
understanding on the impacts of climate on terrestrial
hydrology.