Meeting abstract

IAGA, 8th Scientific Assembly, Uppsala, Sweden, 4-8 August, 1997

Abstract:
We present an overview of energetic ion (~ MeV) data measured by the Anisotropy Telescopes (ATs) instrument on board the Ulysses spacecraft. We concentrate on presenting first order anisotropies in the ion flux observed during a period corresponding to the Ulysses spacecraft's first traversal from the ecliptic plane to high southern latitudes. This interval is subdivided into three regions characterised by significant differences in the measured ion fluxes and magnetic field data. In the first region, at low southern latitudes (<13°S), Ulysses was immersed in the heliomagnetic streamer belt where the fluxes of ~ MeV ions show enhancements of ~2-3 orders of magnitude but without any apparent periodicity. In the second region, as Ulysses sampled latitudes between ~13°S and 29°S, the ~ MeV ion fluxes exhibited enhancements of as much as ~5 orders of magnitude with an approximate 26 day periodicity corresponding to a recurrent corotating interaction region. During this region each of the nine enhancements showed strong first order anisotropies as the flux rose to peak values, and slightly weaker anisotropies as the flux decayed. In the third region, characterised by a disappearance in the magnetic sector structure at higher latitudes (~29°S - 50°S), strong first order anisotropies were still present in the ~ MeV ion fluxes which continued to exhibit periodic enhancements, although somewhat diminished in magnitude compared to the second region.