ABSTRACT
In recent years there has been an increasing demand for improved accuracy and reliability of Earth observation (EO) data. This is stimulated not only by the desire to understand better the workings of Earth and the causes and impacts of climate change, but also because improvements in models allow us to discriminate better between data. A further driver is the increasing reliance on the combination of data from different sensors and sources (satellites, aircraft and in-situ) to establish more sophisticated data products. These will be important for “operational services” of the future, as envisaged in initiatives such as Global Monitoring of Environment and Security (GMES) of the European Union (EU) and European Space Agency (ESA). This combination of data from different sources can only be carried out if each data set has a clear and reliable statement of uncertainties.
