Service and Products for ionosphere Electronic Content and Tropospheric Refractivity  over Europe from GPS data




Recent developments in ionospheric remote sensing, in particular the advent of techniques using the Global Positioning System (GPS), provide an unprecedented capability for monitoring the state of the ionosphere and its reaction to solar events, but also to earth geophysical events. Dual frequency GPS signals allow to monitor, and characterize ionosphere state disturbances on a routine basis with 2D Total Electronic Content (TEC) maps.

The ionosphere is indeed a natural amplifier of ground movements, the vertical velocity at the ground level being amplified by a factor up to 105 as it reaches the ionosphere at low frequencies (f<0.05 Hz). This amplification can be used to detect and study two types of transient geophysical signals. The first ones are produced by an acoustic coupling between the solid earth and the ionosphere or alternatively, by atmospheric explosion, either from volcanoes or asteroids.


Information on the water vapor content of the troposphere can also be extracted from GPS signal. Techniques under development in research laboratories will be addressed during the project in order to characterize the precision of GPS or GALILEO-derived tropospheric products and to assess their usefulness for weather forecasting.


The aims of the project are :

·          To set up a pre-operational service for distribution of ionospheric electronic content products over Europe from GPS data

·          To make this service evolve toward a pre-operational service for distribution of tropospheric products for GPS positioning

·          To use equivalent systems in a laboratory context for the study of post-seismic ionospheric signals over California, Japan and the Mediterranean Sea.

·          To study the ability of dense GPS networks to monitor tsunami

·          To precise and consolidate technology applications and potential business outlets for ionosphere and troposphere products over Europe, in the framework of the preparation of GALILEO

·          To support research in the field of tropospheric products applicable to meteorology, with the aim of having an operational production after 2 years.


Example of 2D TEC maps over Europe during one day


The TEC service will rely on GPS data from a dense network of station over Europe. Primary 30 s data will be processed so as to generate 2D maps of TEC that will be available through an internet server. A particular attention will be put on the automation and reliability of the service. Maps will be produced in slightly delayed mode and will be kept on line during one month. Extraction of off-line products will also be achievable by direct request on the server. Different levels of data processing will be avaible from raw data to side products such as satellite and station bias.


The project will be achieved by a consortium composed of Public Research laboratories and institutes: Institut de Physique du Globe de Paris (IPGP), Centre d'étude des Environnements Terrestre et Planétaires (CETP), Service d’Aéronomie (SA), the last two from the Institut Pierre Simon Laplace (IPSL), Eidgenössische Technische Hochschule of Zürich (ETH), and a private company, NOVELTIS.

The following entities are observers of the project: Laboratoire de géophysique, Tectonique et Sédimentologie –UMR 5573/U. Montpellier II, Centre National de Recherches Météorologiques (CNRM/Météo-France), Laboratoire de Géophysique Interne et Tectonophysique – UMR5559/U. de Grenoble, Laboratoire de Recherche en Géodésie (IGN/LAREG), Office National d’Etudes et de Recherches Aérospatiales (ONERA), Commissariat à l’Energie Atomique, laboratoire de Détection et de Géophysique (CEA/DASE)


This project is funded by the French Ministry of Research (Réseau Terre et Espace), the European Space Agency (Space Weather Pilot Projects) and the French Space Agency CNES (TAOB).


Ionosphere, Total Electronic Content, Natural Hazard, Internet Service, Space Weather European Network (SWENET), earthquake, troposphere, water vapor.

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