F M Ipavich, A B Galvin (Dept. of Physics, University of Maryland, College Park, MD 20740; e-mail: ipavich@umtof.umd.edu); P Bochsler (Physikalisches Institut der Universitt Bern, Bern, Switzerland); H Grünwaldt, M Hilchenbach (Max-Planck-Institut für Aeronomie, Katlenburg-Lindau, Germany); D Hovestadt (Max-Planck-Institut für extraterrestrische Physik, Garching, Germany); F Gliem (Technische Universit and the CELIAS Team

Several interesting phenomena were observed in the solar wind in Jan and Feb of 1997 --- CMEs, magnetic clouds, interplanetary shocks, and a large rarefaction during which the solar wind density dropped to values as low as 0.3/cm3. We report our observations of these structures using the CELIAS/MTOF Proton Monitor (PM) sensor on the SoHO spacecraft. The PM was designed to assist in the interpretation and analysis of the elemental and isotopic composition measurements from the MTOF sensor. In addition, as the only solar wind proton sensor on SoHO, it is used to characterize the state of the solar wind at the L1 position of the SoHO spacecraft. We also report preliminary composition results in these structures from the MTOF sensor.