Charged particle radial gradients in the inner heliosphere (1-5 AU) during the rise to maximum of solar cycle 23
C.G. Maclennan and L.J. Lanzerotti
Bell Laboratories, Lucent Technologies, Murray Hill, NJ USA
R.B. Decker, R.E. Gold, S.E. Hawkins, III, and D. Haggerty
Johns Hopkins University/Applied Physics Lab, Laurel, MD USA
The beginning and rise to maximum of solar cycle 23 has the Ulysses spacecraft
fortuitously placed at ~5 AU near the ecliptic plane and on a trajectory toward
the southern heliosphere pole. The twin instruments, HI-SCALE on Ulysses and
EPAM on the ACE spacecraft (at 1 AU), provide an opportunity at this time in the
solar cycle to investigate the spatial distribution of charged, solar-produced
particles in the near-ecliptic heliosphere inside 5 AU. We report here
examinations and comparisons of the composition (Z > 2 ions) of heliosphere
particles with energies ~0.5-10 MeV/nucl during the years 1998 to the present
as measured at these two locations. In particular, we compare the composition
radial gradients between 1 and 5 AU as a function of helioradius and
heliolatitude, as Ulysses begins its southward swing during its solar maximum
mission. We also show comparisons of the ion composition as a function of
heliolatitude for Ulysses first two orbits over the same southern heliolatitude
range.