Observations of substorm auroras by MAIN cameras system in Apatity during two winter seasons: 2014/2015 and 2015/2016

Abstract

Data of the MAIN cameras (Multiscale Aurora Imaging Network) obtained at Apatity (Kola Peninsula, Russia) during two winter seasons (2014/2015 and 2015/2016) have been used to study the substorms during different solar wind conditions. Solar wind parameters were taken from the 1-min sampled OMNI data base (http://cdaweb.gsfc.nasa.gov/cdaweb/istp_public/). Auroral disturbances were verified by the data of IMAGE magnetometers and by data of the all-sky camera at Apatity. All substorms were divided into different groups depending on the geomagnetic activity. First, the substorms were separated into two groups: substorms observed during storms and substorms under non-storm conditions. The substorms during storms were divided in sub-groups according to observations during different phases of the storm: initial, main and recovery phases, and the recovery phase was divided in near and late recovery phase. We considered also substorms during “structured recovery phase”, when the SYM/H index behavior was highly irregular. The substorms during non-storm conditions were classified as substorms under quiet conditions, when no structures in the solar wind were observed, and as substorms occurred when structures in the solar wind near the Earth were detected, but these structures did not provoke geomagnetic storms. It was shown that the latitude of the substorm onset was controlled by the value of the SYM/H index. Substorms at higher values of SYM/H index occurred to the North from the station zenith, and at smaller SYM/H values – to the South from it. The boundary between both types of substorms in terms of SYM/H index is in the range from ∼ −30 to ∼ −55 nT. It was found out also that the maximal relative intensity of auroras was greater for substorms with onset to the South from Apatity and smaller - for substorms with onset in zenith or to the North from Apatity.