Solar wind magnetic holes can cross the bow shock and enter the
magnetosheath
- Tomas Karlsson,
- Henriette Trollvik,
- Savvas Raptis,
- Hans Nilsson,
- Hadi Madanian
Henriette Trollvik
KTH Royal Institute of Technology, KTH Royal Institute of Technology
Author ProfileSavvas Raptis
Royal Institute of Technology, Royal Institute of Technology
Author ProfileHans Nilsson
Swedish Institute of Space Physics, Swedish Institute of Space Physics
Author ProfileHadi Madanian
Southwest Research Institute, Southwest Research Institute
Author ProfileAbstract
Solar wind magnetic holes are localized depressions of the magnetic
field strength, on time scales of seconds to minutes. We use Cluster
multipoint measurements to identify 26 magnetic holes which are observed
just upstream of the bow shock and, a short time later, downstream in
the magnetosheath, thus showing that they can penetrate the bow shock
and enter the magnetosheath. For two magnetic holes we show that the
relation between upstream and downstream properties of the magnetic
holes are well described by the MHD Rankine-Hugoniot jump conditions. We
also present a small statistic investigation of the correlation between
upstream and downstream observations of some properties of the magnetic
holes. The temporal scale size, and magnetic field rotation across the
magnetic holes are very similar for the upstream and downstream
observations, while the depth of the magnetic holes varies more. The
results are consistent with the interpretation that magnetic holes in
Earth's and Mercury's magnetosheath are of solar wind origin, as has
earlierly been suggested. Since the solar wind magnetic holes can enter
the magnetosheath, they may also interact with the magnetopause,
representing a new type of localised solar wind-magnetosphere
interaction.