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Titolo:
Features of energetic ions near the compressed magnetosphere
Autore:
Chen, JS; Fritz, TA;
Indirizzi:
Boston Univ, Ctr Space Phys, Boston, MA 02215 USA Boston Univ Boston MA USA 02215 niv, Ctr Space Phys, Boston, MA 02215 USA
Titolo Testata:
JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS
fascicolo: 5, volume: 63, anno: 2001,
pagine: 463 - 472
SICI:
1364-6826(200103)63:5<463:FOEINT>2.0.ZU;2-2
Fonte:
ISI
Lingua:
ENG
Soggetto:
EARTHS BOW SHOCK; ULF POWER SPECTRA; CUSP MEV HELIUM; MAGNETIC-FIELD; WIND SPACECRAFT; SOLAR-WIND; UPSTREAM; MAGNETOSHEATH; PARTICLE; POLAR;
Keywords:
magnetosphere; magnetic storms; energetic particles;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
37
Recensione:
Indirizzi per estratti:
Indirizzo: Chen, JS Boston Univ, Ctr Space Phys, 725 Commonwealth Ave, Boston, MA 02215 USA Boston Univ 725 Commonwealth Ave Boston MA USA 02215 MA 02215 USA
Citazione:
J.S. Chen e T.A. Fritz, "Features of energetic ions near the compressed magnetosphere", J ATMOS S-P, 63(5), 2001, pp. 463-472

Abstract

A possible cusp acceleration mechanism has been investigated during a major geomagnetic storm on May 4, 1998 when the magnetosphere was compressed and eroded. At 5:00-12:05 UT, the WIND spacecraft was about 213R(E) upstream from the Earth, the GEOTAIL was in the post dusk magnetosheath, and the POLAR traveled in its outbound orbit from the equatorial radiation belt to thehigh-altitude dayside cusp and crossed the magnetopause into the magnetosheath. Many instances of in situ ion energization (to > MeV) were observed by POLAR during this period. Simultaneous observations indicated that no comparable flux was observed by WIND. Ion fluxes measured by POLAR were higherthan that measured by GEOTAIL, indicating ion source regions near or within the magnetosphere. The measured ions show some interesting features: (I)In the radiation belt, in the magnetopause boundary layer, and in the dayside cusp, most 1-200 keV/e fluxes were around pitch angles of 90 degrees; while in the magnetosheath, the fluxes came from a broad hemispherical direction between similar to sunward and earthward. (2) At around 6:00 UT, the MeVion flux was lower in the magnetosheath than in the adjacent magnetosphere. (3) There were two CEP (cusp energetic particle) events with 2-3 orders of magnitudes enhancements of MeV ion fluxes. (4) The MeV ions in one CEP event had a peak flux higher than that of the intense outer radiation belt inthe equatorial plane. (S)The 100 keV/e O<+3 ions which originated from theionosphere were observed in both the outer cusp and the magnetopause boundary layer. (6) There were no large magnetic field fluctuations upstream before the bow shock. These observations suggest a likely source of substantial particle energization exists in the cusp region. (C) 2001 Elsevier Science Ltd. All rights reserved.

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Documento generato il 25/09/20 alle ore 00:35:23