LATITUDINAL AND RADIAL VARIATION OF SHOCK ASSOCIATED GREATER-THAN-OR-EQUAL-TO-30 KEV-ION SPECTRA AND ANISOTROPIES AT VOYAGER-1 AND VOYAGER-2

The spectra and anisotropies of ions greater than or equal to 30 keV h ave been measured by the Low Energy Charged Particle experiment on Voy agers 1 and 2 in the vicinity of interplanetary shocks between radial distances of 1-55 AU and heliographic latitudes 11 degrees S-32 degree s N. The spectra and anisotropies associated with a recent corotating (CIR) event at low latitude observed at Voyager 2 (36.6 AU, -9 degrees ) are similar to those of another event at high latitude observed at V oyager 1 (49.8 AU, 33.5 degrees). An earlier CIR event observed at Voy ager 2 (14 AU) associated with the previous solar cycle produced spect ra and anisotropies remarkably similar to the more recent events. The anisotropies are used to calculate the solar wind velocity downstream of shocks where possible using the Compton-Getting effect, allowing th e determination of previously unknown velocities at the locations of V oyager 1. For the large shock event observed at Voyagers 1 (38 AU, 30 degrees) and 2 (29 AU, 3 degrees) in mid-1989, the postshock spectra a nd anisotropies are well described by convected power law distribution s. The Voyager 1 and 2 postshock spectra similar to 4 days after the s hock passage are nearly identical. The preshock anisotropies at low en ergy are similar, despite differences in the magnetic field orientatio n and the low energy spectrum. We find that the greater than or equal to 30 keV ion anisotropies are generally well described by convective distributions downstream but not in the upstream region for this shock , and many other shock events at Voyagers 1 and 2.