Scintillation in the Arctic during the May 2024 Mother’s Day storm

The geomagnetic storm that started on May 10th 2024, often referred to as the “Mother’s Day” or “Gannon” storm, was the strongest storm for decades,with polar lights visible across significant parts of the globe. This paper focuses on the impacts in the form of GNSS signal scintillation in the Arctic, covering the geographic area from 50 to 85° N and 160° W to 40° E. The scintillation analysis is supported by ionospheric convection data from the Super Dual Auroral Radar Network (SuperDARN) and currents estimated from the measurements of multiple magnetometer arrays. Positioning performance is examined for a real-time kinematic (RTK) service in Tromsø, at ≈70° N. An overview of the spatial and temporal occurrence of the scintillation is presented. Scintillation was observed throughout the coverage area, in connection with the auroral oval region and a tongue of ionization. Amplitude scintillation was observed but with a lesser magnitude (S4 values up to 0.2) and extent than the phase scintillation. The connection of the scintillation to the auroral electrojets and vertical currents is examined in detail. Scintillation is found to occur within both the eastward and westward electrojets, but is not a constant feature. Phase scintillation in the eastward electrojet tends to occur near the poleward boundary. Some periods of strong vertical currents are associated with scintillation. Accurate positioning services were severely degraded during the event. For many users, they would be unusable for up to 37 consecutive hours. To the best of our knowledge, at the time of writing, this paper presents the most complete overview of high-latitude scintillations during this storm, and demonstrates the value of combining data from multiple instruments for enhanced insight.