Pc5 geomagnetic pulsations, pulsating particle precipitation, and VLF chorus: Case study on 24 November 2006

摘要

The event (24 November 2006, ～0400-0500 UT) of the simultaneous observations of Pc5 ULF geomagnetic pulsations, electron precipitation (CNA riometer absorption), and whistler-mode chorus, as well as solar wind (SW) and IMF parameters have been analyzed based on the data from IMAGE magnetometers, Finnish riometer array, and temporal VLF station. The visible correlation between the simultaneous occurrence of several minutes scale patches of chorus and pulsating CNA enhancements was found. The dynamic spectra of the riometer data showed a maximum at ～3.5 mHz in the first half-hour interval and at ～2.0 mHz in the second one, while the ULF pulsation spectra exhibit these two maxima in both intervals simultaneously. In the first time interval, the Pc5 pulsations at ～3.5 mHz demonstrated the typical FLR feature. The SW dynamic pressure fluctuations showed a broad (1.5-3.5 mHz) spectral maximum in the first interval; however, in the second one, the simultaneous oscillations at ～2.0 mHz were observed in SW pressure and in IMF Bz. The similar ～2.0 mHz peak has been found in the spectra of Pc5 pulsations from auroral zone to the equator, in riometer absorption, and in VLF chorus power. We suggest that the modulation of particle precipitation and whistler-mode chorus patches was caused by the 2.0 mHz compressional component of Pc5 poloidal geomagnetic pulsations driven in the magnetosphere by SW dynamic pressure and IMF Bz disturbances.