Connecting the Sun's High-Resolution Magnetic Carpet to the Turbulent Heliosphere
Steven R Cranmer Submitted: 2013-03-05 13:17
The solar wind is connected to the Sun's atmosphere by flux tubes that are
rooted in an ever-changing pattern of positive and negative magnetic
polarities on the surface. Observations indicate that the magnetic field
is filamentary and intermittent across a wide range of spatial scales.
However, we do not know to what extent the complex flux tube topology seen
near the Sun survives as the wind expands into interplanetary space. In order
to study the possible long-distance connections between the corona and the
heliosphere, we developed new models of turbulence-driven solar wind
acceleration along empirically constrained field lines. We used a
potential-field model of the Quiet Sun to trace field lines into the
ecliptic plane with unprecedented spatial resolution at their footpoints.
For each flux tube, a one-dimensional model was created with an existing
wave/turbulence code that solves equations of mass, momentum, and energy
conservation from the photosphere to 4 AU. To take account of stream-stream
interactions between flux tubes, we used those models as inner boundary
conditions for a time-steady MHD description of radial and longitudinal
structure in the ecliptic. Corotating stream interactions smear out much of
the smallest-scale variability, making it difficult to see how individual
flux tubes on granular or supergranular scales can survive out to 1 AU.
However, our models help clarify the level of ''background'' variability with
which waves and turbulent eddies should be expected to interact. Also, the
modeled fluctuations in magnetic field magnitude were seen to match measured
power spectra quite well.
Authors: S. R. Cranmer, A. A. van Ballegooijen, L. N. Woolsey
Projects: National Solar Observatory (Sac Peak)
Publication Status: ApJ, in press for April 20, 2013 issue, arXiv:1303.0563
Last Modified: 2013-03-06 08:54