SWARM L2PS Dedicated Ionospheric Field Inversion Chain
Chulliat, Arnaud; Vigneron, Pierre; Thébault, Erwan; Sirol, Olivier; Hulot, Gauthier

ESA's Swarm mission, to be launched in July 2013, is an optimized constellation of three low-Earth orbiting satellites providing measurements of the geomagnetic field with unprecedented precision. Over the last two and a half years, a consortium of research institutions has teamed up with ESA to set up the "Swarm L2 Processing System" (L2PS), a distributed processing facility that will produce level-2 data products during the Swarm mission. As a member of the consortium, the IPGP developed the "Dedicated Ionospheric Field Inversion chain" (DIFI). The DIFI algorithm produces global, spherical harmonic and time-varying models of the geomagnetic Sq field, i.e., the magnetic field generated by electrical currents flowing in the conducting layers of the ionosphere, on the dayside of the Earth. It takes into account seasonal effects as well as solar cycle variability. It separates the observed Sq field in two parts: the primary field originating in the ionosphere, and the secondary field induced in the electrical conducting mantle. The obtained models are valid both on the ground and at satellite altitude, and at all latitudes within +/-55°. The DIFI algorithm was thoroughly tested during the development phase of the L2PS, using synthetic Swarm data. A first model based upon real Swarm data will be delivered about 6 months after the end of the Swarm commissioning phase.