Ground-based studies of ionospheric convection associated with substorm expansion

Journal Article · Sat Oct 01 04:00:00 EDT 1994 · Journal of Geophysical Research

DOI:https://doi.org/10.1029/94JA01625· OSTI ID:50532

Kamide, Y ^[1]; Richmond, A D; Emery, B A; Hutchins, C F ^[2]; Ahn, B H ^[2]; Beaujardiere, O de la ^[3]; Foster, J C ^[4]; Heelis, R A ^[5]; Kroehl, H W ^[6]; Rich, F J ^[7]

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1. Nagoya Univ., Toyokawa (Japan)
2. National Center for Atmospheric Research, Boulder, CO (United States)
3. Stanford Research Institute International, Menlo Park, CA (United States)
4. Massachusetts Institute of Technology, Cambridge, MA (United States)
5. Univ. of Texas at Dallas, Richardson, TX (United States)
6. National Geophysical Data Center, Boulder, CO (United States)
7. Hanscom Air Force Base, MA (United States); and others

The instantaneous patterns of electric fields and currents in the high-latitude ionosphere are deduced by combining satellite and radar measurements of the ionospheric drift velocity, along with ground-based magnetometer observations for October 25, 1981. For this purpose, an updated version of the assimilative mapping of ionospheric electrodynamics technique has been used. These global patterns are unobtainable from any single data set. The period under study was characterized by a relatively stable southward interplanetary magnetic field (IMF), so that the obtained electric field patterns do reflect, in general, the state of sustained and enhanced plasma convection in the magnetosphere. During one of the satellite passes, however, an intense westward electrojet caused by a substorm intruded into the satellite (DE 2) and radar (Chatanika, Alaska) field of view in the premidnight sector, providing a unique opportunity to differentiate the enhanced convection and substorm expansion fields. The distributions of the calculated electric potential for the expansion and maximum phases of the substorm show the first clear evidence of the coexistence of two physically different systems in the global convection pattern. The changes in the convection pattern during the substorm indicate that the large-scale potential distributions are indeed of general two-cell patterns representing the southward IMF status, but the night-morning cell has two positive peaks, one in the midnight sector and the other in the late morning hours, corresponding to the substorm expansion and the convection enhancement, respectively. 40 refs., 12 figs., 1 tab.

• Sponsoring Organization: USDOE
• OSTI ID: 50532
• Journal Information: Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Journal Issue: A10 Vol. 99; ISSN JGREA2; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
CONVECTION
ELECTRIC CURRENTS
ELECTRIC FIELDS
ELECTROJETS
IONOSPHERE
POLAR REGIONS
REMOTE SENSING