Ground-based studies of ionospheric convection associated with substorm expansion

Technical Report · Sat Oct 01 04:00:00 EDT 1994

OSTI ID:91723

Kamide, Y; Richmond, A D; Emery, B A; Hutchins, C F; Ahn, B H

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 genernal, 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 epansion and maximum phases of the substorm show the first clear evidence of the coezistence 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 LMF 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.

• Research Organization: Phillips Lab., Hanscom AFB, MA (United States)
• OSTI ID: 91723
• Report Number(s): AD-A--289167/9/XAB; PL-TR--94-2302
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
CONVECTION
ELECTRIC CURRENTS
ELECTRIC FIELDS
IONOSPHERE
MAGNETIC STORMS
SPATIAL DISTRIBUTION
TIME DEPENDENCE