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Title: A DETERMINATION OF THE NORTH–SOUTH HELIOSPHERIC MAGNETIC FIELD COMPONENT FROM INNER CORONA CLOSED-LOOP PROPAGATION

A component of the magnetic field measured in situ near the Earth in the solar wind is present from north–south fields from the low solar corona. Using the Current-sheet Source Surface model, these fields can be extrapolated upward from near the solar surface to 1 AU. Global velocities inferred from a combination of interplanetary scintillation observations matched to in situ velocities and densities provide the extrapolation to 1 AU assuming mass and mass flux conservation. The north–south field component is compared with the same ACE in situ magnetic field component—the Normal (Radial Tangential Normal) Bn coordinate—for three years throughout the solar minimum of the current solar cycle. We find a significant positive correlation throughout this period between this method of determining the Bn field compared with in situ measurements. Given this result from a study during the latest solar minimum, this indicates that a small fraction of the low-coronal Bn component flux regularly escapes from closed field regions. The prospects for Space Weather, where the knowledge of a Bz field at Earth is important for its geomagnetic field effects, is also now enhanced. This is because the Bn field provides the major portion of the Geocentric Solar Magnetospheric Bz fieldmore » coordinate that couples most closely to the Earth’s geomagnetic field.« less
Authors:
; ; ;  [1] ;  [2] ;  [3] ;  [4]
  1. Center for Astrophysics and Space Sciences, University of California, San Diego, La Jolla, CA, 92093 (United States)
  2. RAL Space, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire, OX11 0QX (United Kingdom)
  3. Solar-Terrestrial Environment Laboratory, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601 Japan (Japan)
  4. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, 94305 (United States)
Publication Date:
OSTI Identifier:
22518701
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 803; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPARATIVE EVALUATIONS; CORRELATIONS; DENSITY; EXTRAPOLATION; GEOMAGNETIC FIELD; HELIOSPHERE; MASS; SOLAR CORONA; SOLAR CYCLE; SOLAR WIND; SPACE; STELLAR MAGNETOSPHERES; SUN; SURFACES; VELOCITY