BEXCO - Room F(201/202/203/204)
[SH077] Quasi-27-day enhancements of Jovian electron fluxes in the vicinity of the Earth
- Karoly KECSKEMETY
- Elena DAIBOG (Skobeltsyn Institute of Nuclear Physics, Moscow State University, Russia)
Fluxes of Jovian electrons with repeating time profiles are registered periodically every 13 months (399 days), equal to the synodic period of Earth-Jupiter system. By studying the quasi-27-day variations of Jovian energetic electron fluxes we found deviations of the periodic recurrences from the synodic period of the Sun-Earth system. Two synodic cycles during solar activity minima of 1974-75 and 2007-2008 are considered. In the 1974-75 interval Jovian electrons were observed during 13 successive solar rotations at IMP-8, in the 2007-2008 period 14 recurrences were registered at SOHO. Unexpectedly, the average periodicity of these variations did not coincide with the 27.3 day synodic period of the Sun-Earth system. Whereas in 1974-75 the average period of electron flux maxima was 26.8 days, in 2007-08 it was even shorter, 26.1 days. This deviation from 27.3 days is explained by taking two effects into account: changes in the temporal structure of the solar wind velocity and therefore in the spatial structure of magnetic traps; and the influence of the mutual spatial configuration of the Earth and Jupiter on the periodicity of filling magnetic traps with Jovian electrons and their registration by a near-Earth apparatus.