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Ann. Geophys., 21, 1377-1382, 2003
www.ann-geophys.net/21/1377/2003/
© European Geosciences Union 2003
The global heliospheric magnetic field polarity distribution as seen at Ulysses
G. H. Jones and A. Balogh
Space and Atmospheric Physics Group, The Blackett Laboratory, Imperial College London, London SW7 2BW, UK
Abstract. The Ulysses spacecraft is
in a near-polar solar orbit with a period of 6.2 years. The heliospheric
magnetic field polarity detected by Ulysses from its 1992 Jupiter encounter to
the current time is presented, following ballistic mapping of the polarity
information to the solar wind source surface, at approximately 2.5 solar radii.
The spacecraft’s first foray to polar latitudes and first rapid heliolatitude
scan occurred in 1994–1995, near a minimum in solar activity. The
heliospheric current sheet during this period was confined to low
heliolatitudes. In 2000–2001, Ulysses returned in situ data from the same
region of its orbit as in 1994–1995, but near to the maximum in solar
activity. Unlike at solar minimum, heliospheric current sheet crossings were
detected at the spacecraft over a wide heliolatitude range, which is consistent
with the reversal of the solar magnetic dipole occurring during solar maximum.
Despite complexity in the solar wind parameters during the latest fast latitude
scan (McComas et al., 2002), the underlying magnetic field structure appears
consistent with a simple dipole inclined at a large angle to the solar
rotational axis. The most recent data show the heliospheric current sheet
returning to lower heliolatitudes, indicating that the dipole and rotational
axes are realigning, with the Sun’s magnetic polarity having reversed.
Key words. Interplanetary physics
(interplanetary magnetic fields; sources of the solar wind) – Solar physics,
astrophysics and astronomy (magnetic fields)
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