Reorientation of the IMF Bz Component as a Trigger of Isolated Bursts of Long-Period Pulsations in the Region of the Dayside Polar Cusp

Kurazhkovskaya, N.A.; Klain, B.I.

Авторы: Kurazhkovskaya N.A., Klain B.I.
Журнал: Geomagnetism and Aeronomy
Том: 61
Номер: 4
Год издания: 2021
Издательство: Maik Nauka/Interperiodica Publishing
Местоположение издательства: Russian Federation
Первая страница: 540
Последняя страница: 550
DOI: 10.1134/S0016793221040083
Аннотация: The study of simultaneous observations of isolated bursts of ipcl pulsations (irregular pulsationscontinuous long period) in a frequency range of 1.3–6.3 mHz in the region of the dayside polar cusp and thedynamics of the Bz component of the interplanetary magnetic field (IMF) is carried out. It is found that, isolatedipcl bursts are observed in the cusp region in 61% of cases (first group) after a change in the direction ofthe IMF Bz component from north to south and in 39% of cases (second group) with a change in the Bz directionfrom south to north. The bursts of the two groups had approximately the same spectral composition butdiffered in the intensity, duration of wave packets, and excitation conditions. Depending on the change in thesign of the Bz component (from positive to negative or from negative to positive), the spectral density of ipclpulsations reached the maximum value in 10–20 min or 5–10 min, respectively, after the instant of Bz reorientation.It is shown that the dynamics of other geoeffective parameters of the solar wind and IMF was relativelystable before the reorientation of the Bz component and after, i.e., during the excitation of wave packetsof ipcl pulsations. The totality of experimental facts suggests that the only trigger of isolated ipcl bursts underconditions of a moderately disturbed magnetosphere may be a change in the direction of the IMF Bz component,not only from north to south but also from south to north. A hypothesis is put forward about the excitationof isolated ipcl bursts observed in the dayside cusp region as a result of stationary reconnection both inthe forenoon sector of the magnetosphere and near polar cusps.
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Reorientation of the IMF Bz Component as a Trigger of Isolated Bursts of Long-Period Pulsations in the Region of the Dayside Polar Cuspстатья Исследовательская статья

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