Bursts of Geomagnetic Pulsations and Night Atmosphere Airglow Caused by Solar Wind Pressure Changes During a Magnetospheric Storm

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Abstract The dynamics of geomagnetic disturbances and optical airglow at mid-latitude observatories near Irkutsk during a strong magnetospheric storm in the night sector on October 21, 2001, has been studied. During the storm, three 1.5-hour intervals of increase in the solar wind (SW) dynamic pressure, which caused intensification of substorm activity, bursts of broadband geomagnetic pulsations, and 557.7 and 630.0 nm auroral emissions, were observed. During these bursts, the southern boundary of the zone of field-aligned currents and the auroral oval approached the observation points, but remained 5°–7° to the north. Possible mechanisms of the amplification of pulsations and optical emissions are related to the effects of SW pressure changes on the magnetosphere: substorm activations, changes in field-aligned and ionospheric currents, and precipitation of both energetic and thermal/superthermal electrons. The features of the high-frequency part of the pulsation spectrum and their spatial distribution are associated with properties of the ionospheric Alfven resonator and the ionospheric MHD waveguide.

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