HR: 17:30h
AN: SH32D-07    [PDF]
TI: Acceleration and Transport of Diffuse Protons in the foreshock region of the Earth's Bow Shock
AU: * Terasawa, T
EM: terasawa@eps.s.u-tokyo.ac.jp
AF: Department of Earth and Planetary Science, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan
AU: Saito, Y
EM: saito@stp.isas.ac.jp
AF: Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Sagamihara, 229-8510 Japan
AU: Mukai, T
EM: mukai@stp.isas.ac.jp
AF: Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Sagamihara, 229-8510 Japan
AB: We study the physical characteristics of diffuse protons in the region upstream of the earth's bow shock using the GEOTAIL data set of June-October 1994 which covers not only the nominal nose region (X$>$0) but also both the pre-dawn (X$<$0, Y$>$-70Re) and the post-dusk (X$<$0, Y$<$+60 Re) regions. (Note that the diffuse protons are observed in the post-dusk foreshock region when the IMF is in the 'anti-Parker' spiral direction.) What we have found are: (1) The diffuse protons in the pre-dawn and post-dusk regions have lower intensities and softer energy spectra than in the nose foreshock region. The exponential functional form of their energy spectra, exp(-E/Ec), which have been known from the earlier observations in the nose region, continue to the pre-dawn and post-dusk regions with reducing Ec. (As known in the nose region, we observe that Ec depends on the solar wind velocity and the IMF geometry. That Ec also depends on the spatial position is our new finding.) (2) These diffuse protons are more or less isotropic in the nose foreshock region but have anisotropic pancake distributions in the pre-dawn and post-dusk foreshock regions being convected with the ExB motion of the solar wind plasma. These observations provide important information on the acceleration and transport processes of diffuse protons in the foreshock region of the earth's bow shock.
DE: 2116 Energetic particles, planetary
DE: 2149 MHD waves and turbulence
DE: 2154 Planetary bow shocks
DE: 7851 Shock waves
DE: 7867 Wave/particle interactions
SC: SPA - Solar and Heliospheric Physics [SH]
MN: 2003 Fall Meeting