TY JOUR TI Fractal Characteristics of the Auroral Oval Structure According to the All-Sky Camera Data in Apatity for 2013–2020 KW aurora KW substorm KW particle precipitation KW high-latitude ionosphere KW scaling KW fractal index KW anisotropy KW pulsating auroras KW expansion phase JO Russian Journal of Earth Sciences AU Kozelov, B.V. PY 2025 IS 25 PB Geophysical Center of the Russian Academy of Sciences