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Titolo:
Polar observations of the time-varying cusp
Autore:
Rae, JJ; Lester, M; Milan, SE; Fritz, TA; Grande, M; Scudder, JD;
Indirizzi:
Univ Leicester, Dept Phys & Astron, Radio & Space Plasma Phys Grp, Leicester LE1 7RH, Leics, England Univ Leicester Leicester Leics England LE1 7RH er LE1 7RH, Leics, England Boston Univ, Ctr Space Phys, Boston, MA 02215 USA Boston Univ Boston MA USA 02215 niv, Ctr Space Phys, Boston, MA 02215 USA Rutherford Appleton Lab, Didcot OX11 0QX, Oxon, England Rutherford Appleton Lab Didcot Oxon England OX11 0QX 1 0QX, Oxon, England Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA Univ Iowa Iowa City IA USA 52242 t Phys & Astron, Iowa City, IA 52242 USA
Titolo Testata:
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
fascicolo: A9, volume: 106, anno: 2001,
pagine: 19057 - 19065
SICI:
0148-0227(20010901)106:A9<19057:POOTTC>2.0.ZU;2-6
Fonte:
ISI
Lingua:
ENG
Soggetto:
FLUX-TRANSFER EVENTS; WIND DYNAMIC PRESSURE; DAYSIDE MAGNETOPAUSE; CONVECTION PATTERN; PLASMA; SHAPE; RECONNECTION; SPACECRAFT; SUBSTORMS; LOCATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
35
Recensione:
Indirizzi per estratti:
Indirizzo: Rae, JJ Univ Alberta, Dept Phys, Space Phys Grp, Edmonton, AB T6G 0T1, Canada Univ Alberta Edmonton AB Canada T6G 0T1 onton, AB T6G 0T1, Canada
Citazione:
J.J. Rae et al., "Polar observations of the time-varying cusp", J GEO R-S P, 106(A9), 2001, pp. 19057-19065

Abstract

We present a multi-instrument case study of the signatures associated withthe cusp observed by the Charge and Mass Magnetospheric. Ion Composition Experiment (CAMMICE), Hot Plasma Analyzer (HYDRA) and Magnetic Fields Experiment (MFE) instruments onboard the Polar satellite between 0900 and 1300 UTon October 29, 1996. Characteristic signatures of the midaltitude cusp include ions of energies 10(2)-10(4) eV, electrons of energies 10-10(3) eV, and a structured depression in the local magnetic field, During this cusp pass, ion fluxes in the 1-20 keV range were modulated quasi-periodically on timescales of between 12 and 20 min, while energy-dispersed ion count rates were observed close to the open-closed field line boundary. The particle populations on the cusp field lines are, dominated by H+ and He++ ions (characteristic of magnetosheath-like plasma), and on closed field lines dominatedby uniform fluxes of high-energy (50-200keV) protons, which are not pulsed. The pulsed particle events during this case study occur during both southward and northward interplanetary magnetic field (IMF), but differ slightlyin nature. After the IMF rotated northward, Polar still observed the pulsed particle events, but magneto sheath-like and closed field line particles coexisted on the same magnetic flux tubes. It is not evident as to how thismix of plasma can exist on the same field line during northward IMF. HYDRAalso observed higher-frequency pulsing, hypothesized to be caused by low-latitude transient magnetic reconnection. The simultaneous observation of two different frequency components has not been previously reported in spacecraft observations of the midaltitude cusp. Two further cusp passes during similar conditions are presented. The short-period pulsed particle signatures were observed in all three examples, the longer-period pulsing observed in two. The events differed in duration, most likely owing to the effect of IMF B. on the location of the recolinection site, and hence the location ofthe polar cusp.

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Documento generato il 04/04/20 alle ore 14:08:58