To develop channel models and channel assessment techniques to support the reduction of error introduced by the troposphere by means of local augmention systems and external sensors. To model spatial and temporal correlation of troposperic delay for development of synthetic time series generators. To define covariance elements and distribution of the error of models for GNSS users receivers.

The accuracy of tropospheric excess path length estimation in a GNSS receiver can be increased by using an estimate of current or short-term evolution of atmospheric conditions. This information can be provided by ground or space based sensors and numerical weather prediction systems (like ECMWF for a global scale or HIRLAM/MM5 for regional scale). The models and algorithms to process this type of information and convert it into a message for local augmentation systems need to be develped. The modelling of the spatial and temporal correlation properties of tropospheric effects is also relevant for the development of channel models to be used by system simulation tools.