Simultaneous observations of solar energetic particle events by IMP 8 and the Ulysses cospin high energy telescope at high solar latitudes

摘要

With Ulysses approaching the south solar polar latitudes during a period of high solar activity, it is for the first time possible to study the distribution of solar energetic particles (SEPs) in solar latitude as well as in radius and longitude. From July 1997 to August 2000, Ulysses moved from near the solar equator at similar to5 AU to similar to 67 degrees S latitude at similar to3 AU. Using observations of > similar to 30 MeV protons from Ulysses and IMP-8 at Earth we find good correlation between large SEP increases observed at IMP and Ulysses, almost regardless of the relative locations of the spacecraft. The observations show that within a few days after injection of SEPs, the flux in the inner heliosphere is often almost uniform, depending only weakly on the position of the observer. No clear effect of the increasing solar latitude of Ulysses is evident. Since the typical latitudinal extent of CMEs, which most likely accelerate the SEPs, is only similar to 30 degrees, this suggests that the enhanced cross-field propagation for cosmic rays and CIR-accelerated particles deduced from Ulysses' high latitude studies near solar minimum is also true for SEPs near solar maximum. [References: 7]