Experimental GNSS tomography study in Lisbon (Portugal)

Water vapour variability on the atmosphere plays a crucial role on its dynamic processes, being difficult to quantify. The GNSS atmospheric processing has been developed in the past years providing integrated water vapour estimates. These integrated profiles lack a vertical discretization of the atmospheric processes. Reconstruction of the slant path observation in the satellite line of view allows to study the troposphere heterogeneity. 3D tomographic software was developed to model the troposphere dynamics throughout these GPS measurements. A GNSS network available in an area of 60 km(2) in Lisbon (Portugal) composed by 9 receivers was used for the software testing, and preliminary 4D tomography solutions were obtained. Radiosonde measurements were compared to validate the tomographic inversion solution. This study aims for a preliminary characterization of the 3D water vapour field over this region, which will help to assist the investigation of severe weather episodes.