The magnetic field turbulence near interplanetary shock fronts

Abstract

The power spectra (frequency range 10 −3 to 10 −2 Hz) of the magnetic field fluctuations near i nterplanetary s hock fronts (IPS) are analysed using Venera 13 and Venera 14 data. Ten events in teh period from November, 1981 to February, 1982 typical for IPS passings are evaluated. The event on February 2, 1982 is considered in detail. A sharp increase of the magnetic turbulence downstream the shock front is common to all detected IPS. At a frequency of approx. 10 −3 Hz the spectral density of the IMF fluctuations increases by factors of 50 to 100. The strong field turbulences in the post-shock region last about 6 to 9 hours. The IMF turbulence level decreases significantly (at 10 −3 Hz) within the flare plasma fluxes (driver gas region). In the analysed period four different types of IMF power spectra are found depending on the location of the magnetic turbulence regions: In the post-shock region, near the boundaries of IMF flux tubes, in the quiet solar wind and inside the flare plasma fluxes.