Record Detail

Measurements of multi satellites and geomag-
netic indices are used to investigate the energy budget during
an isolated substorm. The calculation of the energy transfer
from the solar wind to the magnetosphere (parameter ε), the
energy increase of the ring current (U R ), the Joule heating
(U J ), the particle precipitation energy flux (U A ) and their
time-integrated energy dissipation W ε , W R , W J , W A indi-
cates that there should be energy dissipation such as plasma
heating and the energy returned to the solar wind by plas-
moid ejection from the tail. After calculating the spatial
sizes of nine selected BBFs, the energy flux density and
energy transported Earthward or tailward by BBFs, using
observations from three satellites, are found to be differ-
ent during an isolated substorm. The flow thermal energy
is dominant whether the energy is transported Earthward or
tailward under the frozen-in condition in the inner plasma
sheet. From results simultaneously observed by three satel-
lites in the magnetotail, we find that the Earthward energy
transported by the flows can provide the energy dissipation
of W J and W A , where the flows are Earthward for more than
60% of the samples, while the tailward energy transport is
far larger than U A and close to U J , where the flows are
tailward for less than 40% of the samples. The maximum
energy flux density is observed by one satellite to be ac-
companied by large variations, while the maximum energy
transport is observed by another satellite with large energy
flux density and small variations. This suggests misleading
conclusions would be obtained if there were only data from
B Y. Ma
ydma@buaa.edu.cn
1 School of Space and Environment, Beihang University, Beijing,
China
2 Rutherford Appleton Laboratory, Oxfordshire, UK
single (or two) satellites. From our results, BBFs play an
important role in the process of energy transport both Earth-
ward and tailward during this isolated substorm. Data based
on observations from one satellite in the magnetotail could
be easily misinterpreted and should be used cautiously.