Complex Analysis of the Polar Substorm Based on Magnetic, Optical, and Radar Observations near Spitsbergen

Resumo

A comprehensive analysis of the polar substorm registered by IMAGE network stations close to the poleward boundary of the auroral oval has been carried out with THEMIS, CLUSTER, and GEOTAIL satellites in favorable positions for analysis. The observation interval is characterized by a low level of geomagnetic activity. The polar substorm looked like three negative, bay-like disturbances and developed within an ordinary substorm registered at stations in the middle of the auroral zone half an hour before the polar substorm. Each bay-like disturbance of the polar substorm was accompanied by a poleward drift of aurora and westward electrojet, a Pi2 pulsation group, a surge of magnetic activity over the range of 0.1–10 Hz, and enhancement of electronic precipitations over Spitsbergen. The differences between the first activation and two subsequent ones in the aurora dynamics, ionospheric convection, and electronic precipitations are revealed. The disturbed zone longitudinal sizes and position in the magnetosphere are estimated. Possible causes of the substorm onset and disturbances associated with it are discussed. The results of the study expand the statistics on the polar substorm phenomenon and will enable insight into its nature.