Return to "The Structure of the Magnetosphere" by
C. T. Russell.
"Evidence for Magnetic Field Reconnection at the Earth's Magnetopause:"
This is a brief summary of
"Evidence for Magnetic Field Reconnection at the Earth's Magnetopause"
by B.U.O. Sonnerup, G. Paschmann, I. Papamastorakis, N. Sckopke,
G. Haerendel, S. J. Bame, J. R. Asbridge, J. T. Gosling and
C. T. Russell.
This paper was one of the references in C. T. Russell's "The
Structure of the Magnetopause," which I am attempting to
summarize.
Unlike "Magnetic Field Rotation Through the
Magnetopause" by J. Berchem and C. T. Russell[1982],
"Evidence for Magnetic
Field Reconnection" consists of carefully chosen data sets analyzed
to provide evidence for dayside reconnection. The plasma velocity
in the magnetopause and boundary layer in each case was considerably
greater than the velocity of the magnetosheath plasma, which allowed each
event to be singled out.
Berchem and Russell chose their events based on the behavior of the
magnetic field, and found very little evidence supporting theories
of rotational discontinuities and reconnection.
The
ISEE satellites, crossing a magnetopause with a thickness of
approximately 700 km, observed eleven events which were analyzed
using several predictions and tests. Tangential magnetic and electric
fields and velocity as well as magnetic fields and velocities normal to the
magnetopause (which was determined by variance methods), as well as
tests of topology and component directions were all implemented.
Overall, the direction and magnitudes of the tangential magnetic
fields and flow velocity seemed to confirm the findings of
Paschmann et al. [1979], as 10 out of
11 events agreed with the predictions of standard reconnection in the
dayside northern hemisphere. The error in measuring the
normal magnetic field prevented any clear analysis, but the general
direction of the field concurred with predictions.
Other tests were not nearly as conclusive as the tangential velocity
predictions, although the topological analysis provided some evidence
of reconnection. The instrumentation and the
variance method of analysis did not provide sufficient accuracy to
compile further support for reconnection. However, little evidence
against reconnection surfaced in this analysis, and more direct
confirmation of reconnection would have required more accurate
instrumentation, which wasn't available. Overall, the results were
about as positive as could be expected at the time, and the authors
strongly urge the reader to accept the events as proof of reconnection.
Return to "The Structure of the Magnetosphere" by
C. T. Russell.