HR: 14:55h
AN: SH13B-06    [Abstracts]
TI: Motion of the Earth's magnetopause: Estimation from low-energy neutral atom emissions
AU: * Hosokawa, K
EM: hosokawa@ice.uec.ac.jp
AF: The University of Electro-Communications, Chofugaoka 1-5-1, Chofu-shi, Tokyo, 182-8585, Japan
AU: Taguchi, S
EM: taguchi@ice.uec.ac.jp
AF: The University of Electro-Communications, Chofugaoka 1-5-1, Chofu-shi, Tokyo, 182-8585, Japan
AU: Suzuki, S
EM: shin.s@ice.uec.ac.jp
AF: The University of Electro-Communications, Chofugaoka 1-5-1, Chofu-shi, Tokyo, 182-8585, Japan
AU: Nishizawa, R
EM: nishizawa@ice.uec.ac.jp
AF: The University of Electro-Communications, Chofugaoka 1-5-1, Chofu-shi, Tokyo, 182-8585, Japan
AU: Collier, M R
EM: michael.r.collier@nasa.gov
AF: NASA/Goddard Space Flight Center, Greenbelt, Maryland, 20771, United States
AU: Moore, T E
EM: thomas.e.moore@gsfc.nasa.gov
AF: NASA/Goddard Space Flight Center, Greenbelt, Maryland, 20771, United States
AU: Thomsen, M F
EM: mthomsen@lanl.gov
AF: Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, United States
AB: On April 13, 2001 the high pressure solar wind impinged on the Earth and moved the magnetopause inside of geosynchronous orbit. During this interval, the Low Energy Neutral Atom (LENA) imager onboard the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) spacecraft observed significant amount of ENA flux in the direction of the dayside low-latitude magnetosheath. This ENA flux is primarily a result of enhanced charge exchange between the increased solar wind plasma and the exospheric hydrogen neutral. We have developed a method of deriving the stand-off distance of the dayside magnetopause directly from this ENA emission, which enables subsolar distance of the magnetopause to be monitored continuously for an hour. Location of the magnetopause estimated from ENA measurements is found to be well consistent with the in-situ measurement of the magnetopause crossings by the LANL-01A spacecraft on geosynchronous orbit. We also estimated velocity of the inward/outward motion of the dayside magnetopause. Estimated velocities of the magnetopause are typically in between -50 to 50 km/s during this interval, which are very close to the values derived from the recent multi-spacecraft observations of the magnetopause. Our result also shows that the motion of the boundary can be changing very rapidly and that its speed sometimes reaches the order of 100 km/s in response to the arrival of the interplanetary shock, demonstrating that the dayside magnetopause moves at very high acceleration.
DE: 2700 MAGNETOSPHERIC PHYSICS (6939)
DE: 2728 Magnetosheath
DE: 2740 Magnetospheric configuration and dynamics
DE: 2794 Instruments and techniques
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2007 Fall Meeting