Contribution of DORIS System to Global Ionospheric Scintillation Mapping

Ionospheric scintillations due to ionosphere irregularities may severely degrade GNSS data in equatorial and high latitudes regions, and consequently the applications that rely on such data. It is thus of high importance for many users in a large variety of applications to have access to global maps of scintillation intensity, for both signal phase and amplitude. Typically, networks of ground based GNSS receivers are used to derive those maps, but it inevitably leads to sparse coverage. In order to mitigate this weakness, the current study proposes to add original data points based on the DORIS system. DORIS (Doppler Orbitography by Radiopositioning Integrated by Satellite) is a French orbitography system, developed primarily for altimetric purposes by the Centre National d’Etudes Spatiales (CNES), the Institut National de l’information géographique et forestière (IGN) and the Groupe de Recherche de Géodésie Spatiale (GRGS). It consists of a network of around sixty ground-based beacons emitting a radio-frequency signal at 400 MHz and 2 GHz. The on-board receivers (on 9 civilian satellites as of January 2024) then performs Doppler shift measurements that allow precise orbit determination.  Despite a lower data rate (0,1 Hz instead of 1 Hz for the GNSS) and a lower number of satellites, DORIS can add valuable information where there is no GNSS receivers, or by taking advantage of its geometry, in particular with polar satellites. In this study, we will explore to what extent it is possible to define scintillation proxies based on DORIS data losses, phase signal degradation, or power signal attenuation, by a comparison to a scintillation data base from GNSS measurements. Eventually, we will discuss whether the challenging near-real time basis delay is achievable.