Title: Low Energy Neutral Atom Signatures of
1Low Energy Neutral Atom Signatures of
Magnetopause Motion in Response to Southward Bz
Michael R. Collier, Thomas E. Moore, Hina Khan,
and Steve Snowden
2XMM X-ray Observations of Solar Wind Charge
Exchange
Sun pulse brightens considerably at time of
solar wind density enhancement. Plan to break
interval up in time and compare NSW observations
with X-ray fluxes.
3Magnetosheath Neutral Atom Emissions
But, sun pulse brightening and sheath emission
only require a magnetopause that is closer to the
Earth - not necessarily higher solar wind ram
pressure. One way to move the magnetopause
closer to the Earth is to erode it with southward
Bz.
4The April 18, 2001 Event
On April 18, 2001, LENA observed sheath
emissions and sun pulse modulation. But between
0100 and 0430, the solar wind ram pressure was
steady.
5Correlation Between LENA Data and Bz
Time-shifted cross-correlation does show a peak
consistent with the solar wind convection
time. Peak correlation not that high
(1) The relationship between Bz and emission is
highly non-linear. (2) Multi-spacecraft studies
show that the IMF does not correlate well even
with itself. (3) The LENA observations are line
of sight and the B-field observations are at a
single point.
6- Sun Pulse/Sheath Brightenings and Radar Data
- Strong correlation between LENA data and
backscattered radar power from Tiger
7LENA Movie of Sun Pulse Modulation with IMF Bz
Sun pulse brightens in association with more
southward turnings of the IMF while dimming
in response to northward turnings.
8Conclusions
- Have simultaneous observations of solar wind
charge exchange in X-rays and low energy neutral
atoms (June 1-2, 2001, day 152-153). - During the April 18, 2001 (day 108) event,
neutral solar wind fluxes are modulated by the
interplanetary magnetic field and interpreted as
due to magnetopause erosion. - Signatures associated with reconnection are
observed at IMAGE and by the Tiger radar at about
the same time (within a few minutes), which
supports this association.