HR: 1330h
AN: SH42A-0474    [PDF]
TI: Evolution of interplanetary magnetic clouds from 0.3 AU to 1 AU: A joint Helios-Wind Study
AU: Biernat, H K
AF: Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, Graz, 8042 Austria
AU: Biernat, H K
AF: Institute for Geophysics, Astrophysics, amd Meteorology, University of Graz, Universit\"atsplatz 5, Graz, 8010 Austria
AU: Biernat, H K
AF: Institute for Theoretical Physics, University of Graz, Universit\"atsplatz 5, Graz, 8010 Austria
AU: * Farrugia, C J
AF: Institute of the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH 03824 United States
AU: * Farrugia, C J
AF: Physics Department, University of New Hampshire, Durham, NH 03824 United States
AU: Leitner, M
EM: martin.leitner@stud.uni-graz.at
AF: Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, Graz, 8042 Austria
AU: Leitner, M
EM: martin.leitner@stud.uni-graz.at
AF: Institute for Geophysics, Astrophysics, amd Meteorology, University of Graz, Universit\"atsplatz 5, Graz, 8010 Austria
AU: Kucharek, H
AF: Institute of the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH 03824 United States
AU: Schwenn, R
AF: Max-Planck-Institut f\"ur Aeronomie, Max-Planck-Str. 2, Katlenburg-Lindau, 37191 Germany
AU: Berdichevsky, D
AF: Labaratory for Extraterrestrial Physics, NASA Goddard Space Flight Center, Greenbelt, MD 20771 United States
AU: Osherovich, V
AF: Labaratory for Extraterrestrial Physics, NASA Goddard Space Flight Center, Greenbelt, MD 20771 United States
AU: Lepping, R P
AF: Labaratory for Extraterrestrial Physics, NASA Goddard Space Flight Center, Greenbelt, MD 20771 United States
AU: Matsui, H
AF: Institute of the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH 03824 United States
AB: A class of interplanetary configurations which interact strongly with the Earth's magnetosphere are interplanetary magnetic clouds. A desideratum of space weather predictions is that they be made from data acquired by distant probes so as to guarantee as long a lead time as possible. For this to be viable, one must have accurate knowledge of how parameters evolve. To this end, we use observations of magnetic cloud made by the spacecraft Wind at 1 AU, and Helios 1 \& 2 between 0.3 and 1 AU. A model is constructed, regarding the magnetic cloud as a cylindrically symmetric, force-free constant-alpha magnetic field configuration, i.e. the cylindrically symmetric solution of $\nabla \bf B = \alpha \bf B$. We least--squares fit the model to the data and obtain model parameters, e.g. the magnetic field strength on the axis of the tube, the helicity, the orientation, the diameter, and its orientation. We adopt two approaches: In the first we obtain statistically the way these parameters evolve with distance from the Sun. In the second approach we focus on line-ups of the spacecraft and determine directly how parameters scale with distance. The two approaches are compared. This work is supported by NASA Living with a Star under grant NAG 5-10883.
DE: 2111 Ejecta, driver gases, and magnetic clouds
SC: SPA - Solar and Heliospheric Physics [SH]
MN: 2003 Fall Meeting