Polar convection and Birkeland currents during strongly positive IMF B sub y

Journal Article · Wed Apr 01 04:00:00 EST 1987 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA092iA04p03417· OSTI ID:5596378

Minyun, Zi ^[1]; Nielsen, E ^[2]; Hanson, W B ^[3]; Potemra, R A ^[4]

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1. Peking Univ. (China)
2. Max-Planck-Inst. for Aeronomy, Lindau (West Germany)
3. Univ. of Texas, Richardson (United States)
4. Johns Hopkins Univ., Laurel, MD (United States)

The TRIAD satellite passed directly over the field of view of the Scandinavian Twin Auroral Radar Experiment (STARE) radar on May 1, 1978, at approximately 0618 UT when the B{sub y} component of the interplanetary magnetic field (IMF) was unusually large in comparison to the other two components. The average IMF values in the interval from 0600 to 0700 UT on this day were B{sub x} = {minus}1.8 nT, B{sub y} = 8.7 nT, and B{sub z} = {minus}0.2 nT (King, 1979). The TRIAD magnetic field perturbations revealed the presence of a very intense ({Delta}B {approximately} 500 nT) region 1 downward-flowing Birkeland current near 0930 MLT and poleward of a much weaker upward-flowing region 2 current. This net Birkeland current was located equatorward of a region of intense westward ionospheric convection flow detected by the STARE radar. The authors conclude that the polar cap convection flow is distorted and displaced to low latitudes (< 67{degree} magnetic latitude) in the morning sector during this period of strongly positive B{sub y} and almost negligible B{sub x} and B{sub z}. The large net region 1 Birkeland current is associated with the convection flow reversal. Convection velocity data acquired by the AE-C satellite on October 29, 1978, near 1723 UT when B{sub x} = {minus}0.5 nT, B{sub y} = 8.3 nT, and B{sub z} = {minus}2.7 nT show the convection reversal near 67{degree} invariant latitude and 0800 MLT. These two examples support previous suggestions for the important influence that the B{sub y} component of IMF has on the intensity and location of high-latitude convection and Birkeland currents.

• OSTI ID: 5596378
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 92:A4; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
&amp; Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAL ZONES
CONVECTION
CURRENTS
DATA ANALYSIS
EARTH ATMOSPHERE
ELECTRIC CURRENTS
ENERGY TRANSFER
HEAT TRANSFER
INTERPLANETARY MAGNETIC FIELDS
IONOSPHERE
MAGNETIC FIELDS
MASS TRANSFER
MEASURING INSTRUMENTS
ORIENTATION
PLANETARY IONOSPHERES
POLAR REGIONS
RADAR
RANGE FINDERS
SATELLITES