A series of disturbances occurred in September 2017, initiated with a solar flare on 6 September. We welcome inputs with observations from the solar-magnetosphere-ionosphere coupled system, and remarks on the effects in aerospace and ground systems.
The research group of Astronomy and GEomatics (gAGE/UPC) has analyzed the impact of the solar flare occurred in September 6 th of 2017 (day of year 249) in three navigation systems: EGNOS (the European SBAS system), PPP and NRTK.
The basic conclusion of the study is that the Solar flare, itself, shouldn’t have a direct impact in any of the 3 navigation systems: we have only found impacts in technical aspects linked indirectly to the Solar flare (i.e. the fast increasing of the STEC) and could be corrected with an adequate treatment. These impacts are:
– Some receivers are unable to track fast changes in the STEC and present multiple loss of lock on practically all the measurements affected by the Solar flare. This is the case for the EGNOS RIMS-A receivers but not for the EGNOS RIMS-B receivers that keep up the tracking during the Solar flare.
– In high accuracy services, as PPP or RTK, if the cycle slip detector tool is based on the geometry-free combination and works over data collected at low rate, the sudden variation of STEC can be erroneously interpreted as cycle slips. This erroneous detection degrades the navigation solutions. However, this not occur if the data were collected at higher rates.