Towards High Resolution Soil Moisture Observation from Space

The need for more accurate, higher-resolution and longer-lasting weather forecasts 
has continued to increase in recent years. In order to meet this need, the input data 
used must, among other things, be provided in high resolution. This is a problem for
soil moisture. 
Large-scale observations of soil moisture are usually carried out using space-born 
microwave instruments. A high spatial resolution requires a large antenna. The maximum 
spatial resolution is therefore limited by the design of the satellite. 

The proposed algorithm for a higher resolution soil moisture product combines a low 
resolution microwave based soil moisture product with higher resolution reflectivities 
in the red and near infrared. This allows to use any microwave product in combination 
with any imager featuring AVHRR heritage channels.
The soil moisture for vegetated pixel is derived by the NDVI itself and for bare land
from water absorption. To prevent soil moisture values from drifting and to make
sure the overall good quality on the rough scale is preserved, a scaling towards
microwave product is performed.

In this presentation we will show intercomparisons of derived soil moisture with in
situ surface observations. Different sources of errors will be discussed and possibilities
to reduce their influence.