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Effects in the upper atmosphere and ionosphere in the subauroral region during Victory Day 2024 Geomagnetic Storm (May 10–12, 2024)
In the subauroral zone at the boundary of the auroral oval in the evening and night hours duringgeomagnetic disturbances, a narrow (about 1º-2º) and extended structure (several hours in longitude) isformed. It is known as a polarization jet (PJ) or the sub-auroral ion drift (SAID). The PJ/SAID is a fastwestward ion drift and is one of the main signatures of a geomagnetic disturbance in the subauroralionosphere at the altitudes of the F-layer, when the geomagnetic AE index reaches more than 500 nT.Plasma speed in the PJ/SAID can reach several kilometres per second, and the size of plasmairregularities inside it can reach scales from tens of meters to several hundred meters. Such highvelocities and structured plasma can affect trans-ionospheric radio signals and lead to scintillations inthe received signal. We show that at the moment of auroral activity intensifi cation, an increase in themagnitude of phase scintillation index (σϕ) as well as loss of satellite signals lock were observed in theregion of the PJ/SAID equatorward of the auroral oval over Dronning Maud Land (Queen Maud Land) inAntarctica. We fi nd that fl uctuations inside the PJ/SAID can lead to serious deterioration of radiocommunication or navigational services. We emphasize the importance of considering the geometry ofthe beam passing from the GNSS satellite to the receiver on the ground. We highlight the mutualcontribution of the PJ/SAID and the diffuse aurora boundary, which are almost impossible to separate inpractice. Our results demonstrate the importance of considering the subauroral zone, where verydynamic plasma formations can occur with a strong fl ow and various-scale irregularities inside that leadto serious interference in satellite communications.