HR: 0800h
AN: SH31A-1164    [Abstracts]
TI: Variability of the Heliospheric Magnetic Flux
AU: * Lepri, S T
EM: slepri@umich.edu
AF: University of Michigan, 2455 Hayward St., Ann Arbor, MI 48109-2143 United States
AU: Antiochos, S K
EM: antiochos@nrl.navy.mil
AF: Naval Research Laboratory, Code 7675, Washington, DC 20375-5352 United States
AU: Zurbuchen, T H
EM: thomasz@umich.edu
AF: University of Michigan, 2455 Hayward St., Ann Arbor, MI 48109-2143 United States
AB: There has been considerable controversy in recent years over the slow evolution of the Sun's open field, which extends out to become the heliospheric magnetic field. In the standard solar model [e.g., Wang and Sheeley, 1993] the open flux can increase or decrease in response to the emergence or cancellation of magnetic flux at the photosphere. In particular, the appearance of a new active region can lead to the formation of a new coronal hole, or the growth of an old one, which should be detectable as a long-term increase in the radial component of the magnetic field throughout the heliosphere. In the Fisk et al. [1999a, 1999b] model, on the other hand, the open flux is conserved and evolves primarily via interchange reconnection with closed field. This model predicts no long-term variations in the amount of heliospheric flux. To compare and test these competing theories, we measure the behavior of the open magnetic flux in the global heliospheric magnetic field. Using multi-point measurements from both the MAG instrument on the Advanced Composition Explorer (ACE) and the VHM instrument on the Ulysses spacecraft, we analyze in-situ magnetic field data. In particular, we examine the radial component of the magnetic field in data from 1998 through 2004 in order to determine the variablity of the open flux and its relation to variations in the area of coronal holes. We describe the implications of our results for the two theories. This work has been supported in part by NSF and NASA.
DE: 2134 Interplanetary magnetic fields
DE: 2162 Solar cycle variations (7536)
DE: 2164 Solar wind plasma
DE: 2169 Sources of the solar wind
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2004 AGU Fall Meeting