SH43C-03
Determination of the North-South Heliospheric Magnetic-Field Component from Inner-Corona Closed-Loop Propagation
Thursday, 17 December 2015: 14:16
2011 (Moscone West)
Bernard V Jackson1, Hsiu-Shan Yu1, P. Paul Hick1, Andrew Buffington1, Mario Mark Bisi2, Munetoshi Tokumaru3, Jaehun Kim4, Sunhak Hong4, Bowon Lee5, Jonghyuk Yi5 and Jongyeon Yun5, (1)University of California San Diego, Center for Astrophysics and Space Science, La Jolla, CA, United States, (2)Rutherford Appleton Laboratory, Didcot, United Kingdom, (3)Nagoya University, Nagoya, Japan, (4)Korean Space Weather Center, Jeju-Si, South Korea, (5)Space Environment Laboratory, 150-gil, Gangnam-gu, Seoul, South Korea
Abstract:
We find that a portion of the north-south interplanetary magnetic field measured in situ near Earth is present from a direct outward mapping of closed fields from the low solar corona. Using the Current-Sheet Source Surface (CSSS) model (Zhao & Hoeksema, 1995 JGR 100, 19), these lower coronal fields are extrapolated upward from near the solar surface. Global velocities inferred from a combination of observations of interplanetary scintillation (IPS) matched to in-situ velocities and densities measured by spacecraft instrumentation provide an accurate outward timing to 1 AU from a model assuming conservation of mass and mass flux. The north-south field component at 1 AU is compared with the appropriate ACE magnetometer in-situ Normal (RTN) or Bn field coordinate (Jackson et al., 2015, ApJL, 803:L1). From a significant positive correlation between this method of determining the Bn field compared with in-situ measurements over a three-year period during the last solar minimum, we find that a small fraction of the low-coronal Bn component flux (~1%) regularly escapes from closed-field regions. Since the Bn field provides the major portion of the Geocentric Solar Magnetospheric (GSM) Bz field component that couples most closely to the Earth’s geomagnetic field, the prospects for its determination using this technique for space weather use are being actively developed by our many colleague groups.
