Supersubstorms and geomagnetically induced currents on 10 May 2024

Very strong magnetic storm (superstorm) with Kp = 9 and Dst = -406 nT occurred on 10-13 May 2024. The superstorm was characterized by a gradual, three-step main phase development with maximum at ~ 02:14 UT on 11 May (SYM/H = -518 nT), and the prolonged recovery phase until May 13. At the background of the storm additional geomagnetic activities were also registered – intense substorms and geomagnetic pulsations. Recent studies have shown that substorms development was main source of intense geomagnetically induced currents (GICs) occurred in the night sector, whereas Pi3/Pc5 geomagnetic pulsations were primary sources of intense GICs in the morning sector. Besides, extremely intense geomagnetic disturbances, so-called supersubstorms (SSSs: SML<−2500 nT), were recorded during the main phase of the May storm: at ~19:20 UT, ~19:50 UT and ~ 22:40 UT on 10 May 2024. The aim of this study is to analyze the enhancement of GICs in electrical circuits in the northwest of Russia during supersubstorms recorded at the main phase on 10 May 2024. The appearance of GICs were monitored using data from stations Vykhodnoy (VKH), Loukhi (LKH) and Kondopoga (KND) in the northwestern Russia (PGI, EURISGIC, eurisgic.ru). The planetary spatiotemporal distribution of the magnetic disturbances was examined using data from ground-based magnetometer networks (SuperMAG and IMAGE) as well as the magnetic field measurements from the Iridium constellation of 66 satellites at an altitude of ~780 km, distributed over six orbital planes equally spaced in longitude (AMPERE project). The fine spatiotemporal structure of electrojet development during the supersubstorms was investigated using latitudinal profiles of the equivalent currents derived from MIRACLE system. It was shown that extremely intense GICs were not recorded during supersubstorms, despite the fact that the GIC measurement stations were located in night sector at this time. Possible reasons for the absence of strong GICs in electrical circuits in the northwest of Russia during the development of the supersubstorms on May 10 2024 are discussed.