Time Variations of the Modulation of Anomalous and Galactic Cosmic Rays
E.R. Christian, T.T. von Rosenvinge
    NASA/Goddard Space Flight Center, Greenbelt, MD, USA
C.M.S. Cohen, A.C. Cummings, J.S. George, R.A. Leske, R.A. Mewaldt, E.C. Stone
    California Institute of Technology, Pasadena, CA, USA
P.L Slocum, M.E. Wiedenbeck, N. Yanasak
    Jet Propulsion Laboratory, Pasadena, CA, USA
W.R. Binns, P.L. Hink, J. Klarmann, M. Lijowski
    Washington University, St. Louis, MO, USA

Since the start of solar cycle 23 in 1997, the intensities of galactic rays at 1 AU have dropped by more than 30%, and the anomalous cosmic rays have decreased by an even larger amount. The instantaneous level of modulation is a combination of short-term "Forbush decreases" and the long-term solar cycle. The large collecting power and high resolution of the Cosmic Ray Isotope Spectrometer (CRIS) and the Solar Isotope Spectrometer (SIS) instruments on the Advanced Composition Explorer (ACE) allow us to investigate the changing modulation on short time scales and at different rigidities. With these data, we will study the differences between the short term and long term effects and the correlation of these effects with magnetic field, current sheet tilt angle, and other phenomena.