HR: 13:30h
AN: SH23C-01 INVITED     [Abstracts]
TI: Using the potential field source model to predict the ambient solar wind
AU: * Arge, C N
EM: nick.arge@hanscom.af.mil
AF: AFRL/VSBXS, 29 Randolph Road, Hanscom AFB, MA 01731-3010 United States
AU: Odstrcil, D
EM: Dusan.Odstrcil@noaa.gov
AF: CU/CIRES and NOAA/SEC, NOAA/ National Weather Service National Centers for Environmental Prediction Space Environment Center, W/NP9 325 Broadway, Boulder, CO 80305 United States
AU: de Toma, G
EM: detoma@hao.ucar.edu
AF: NCAR/HAO, 3450 Mitchell Lane , Boulder, CO 80301 United States
AB: The potential field source surface model (PFSS) was developed independently by Schatten et al. [1969] and Altschuler et al. [1969]. The model is magnetostatic in nature and makes two major simplifying assumptions about the large-scale corona: 1) there is zero current in the coronal region between the photosphere and an imaginary spherical surface (i.e., the source surface) positioned typically between 2-3 Rs from Sun center and 2) the field is radial at the source surface. The latter assumption is essentially an attempt to account for the fact that the solar magnetic field is frozen into the coronal plasma and is being dragged along as it flows radially out into the heliosphere. While both assumptions are clearly gross over-simplifications of the true state of the corona, the PFSS model nonetheless works well at describing the large-scale, quasi-steady state of the corona field. In fact, the model has been shown [Wang et al. 1992, 1996, and 2001] to reproduce reasonably well, over multiple solar cycles, the observed coronal hole patterns, and for 3-month running averages, the interplanetary magnetic field (IMF) strength and solar wind speed at L1. In addition, the PFSS model and the more advanced MHD coronal models have been shown [Neugebauer et al., 1998] to reproduce equally well the size, shape, and positions of observed coronal holes and the observed heliospheric field sector structure. Work by Arge et al. [2000, 2002, and 2004] demonstrates that the model can successfully predict, on time-scales of less than a day, the ambient solar wind speed and IMF polarity 3-5 days in advance. In this talk, we provide a brief overview of the PFSS model and how its predictions compare with observations. I then describe our efforts to use it to predict the ambient solar wind.
DE: 2102 Corotating streams
DE: 2169 Sources of the solar wind
DE: 7509 Corona
DE: 7511 Coronal holes
DE: 7524 Magnetic fields
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2005 Joint Assembly