Lancaster EPrints

A statistical comparison of hot-ion properties at geosynchronous orbit during intense and moderate geomagnetic storms at solar maximum and minimum.

Zhang, Jichun C. and Liemohn, Michael W. and Thomsen, Michelle F. and Kozyra, Janet U. and Denton, Michael H. and Borovsky, Jospeh E. (2006) A statistical comparison of hot-ion properties at geosynchronous orbit during intense and moderate geomagnetic storms at solar maximum and minimum. Journal of Geophysical Research - Space Physics, 111 (A07206). pp. 1-16. ISSN 0148-0227

[img]
Preview
PDF (art_782.pdf)
Download (915Kb) | Preview

    Abstract

    Hot-ion measurements at geosynchronous orbit from the Los Alamos Magnetospheric Plasma Analyzer (MPA) instrument during geomagnetic storms at solar maximum (July 1999–June 2002) and at solar minimum (July 1994–June 1997) are collected, categorized, and analyzed through the superposed epoch technique. To investigate this source of the storm-time ring current, the local time (LT) and universal time (UT) dependence of the average variations of hot-ion fluxes (at the energies of ∼30, ∼17, ∼8, and ∼1 keV), density, temperature, entropy, and temperature anisotropy are examined and compared among four storm categories, i.e., 44 intense storms and 120 moderate storms, defined by the pressure corrected Dst (Dst*), at the two solar extrema. All the hot-ion parameters are highly disturbed around Dst*min; they show distinct peaks or minima and display obvious increase or decrease regions, whose locations do not change much with levels of geomagnetic activity and solar activity. It is also found that intense storms at solar minimum always have the highest (lowest) average peak value (minimum) in each hot-ion parameter. Around Dst*min in each storm category, hot ions are clearly denser near dawn than those near dusk. On the nightside and in the afternoon sector, temperature and entropy during solar minimum storms are usually higher than those during solar maximum storms; there is actually no clear temperature and entropy enhancement during solar maximum storms. During each type of storm, hot ions are isotropic on the nightside but anisotropic (T per /T par > 1) close to noon.

    Item Type: Article
    Journal or Publication Title: Journal of Geophysical Research - Space Physics
    Additional Information: Copyright (2006) American Geophysical Union.
    Uncontrolled Keywords: storm geosynchronous lanl DCS-publications-id ; art-782 ; DCS-publications-personnel-id ; 123
    Subjects: UNSPECIFIED
    Departments: Faculty of Science and Technology > Physics
    ID Code: 28046
    Deposited By: Dr Steve Marple
    Deposited On: 02 Nov 2009 14:52
    Refereed?: Yes
    Published?: Published
    Last Modified: 26 Jul 2012 16:43
    Identification Number:
    URI: http://eprints.lancs.ac.uk/id/eprint/28046

    Actions (login required)

    View Item