Simultaneous measurement of aurora-related, irregular magnetic pulsations at northern and southern high latitudes

Journal Article · Sun Nov 01 00:00:00 EST 1987 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA092iA11p12221· OSTI ID:5962014

Arnoldy, R L; Rajashekar, R ^[1]; Cahill, Jr, L J ^[2]; Engebretson, M J ^[3]; Rosenberg, T J ^[4]; Mende, S B ^[5]

---

1. Univ. of New Hampshire, Durham (United States)
2. Univ. of Minnesota, Minneapolis (United States)
3. Augsburg Coll., Minneapolis, MN (United States)
4. Univ. of Maryland, College Park (United States)
5. Lockheed Research Lab., Palo Alto, CA (United States)

A dominant feature of high-latitude magnetic pulsations is large-amplitude irregular pulsations (Pi) which are closely correlated with the movement of the observing station under particle precipitation, producing the dayside auroral and the high-latitude expansion of nightside aurora. The dayside Pi-1 pulsation maximum centered about local magnetic noon has no strong seasonal dependence, indicating that the dayside aurora illuminates both hemispheres independent of the latitude of the subsolar point. The summer noon pulsation maximum has, however, a greater longitudinal extent than the winter noon maximum, as measured at 74{degree}-75{degree} invariant latitude. The nightside magnetic pulsations are bursts of Pi (PiB) having an average duration of 15 min. From Defense Meteorological Satellite Program photos the auroral forms related to the high-latitude PiB can be identified as the poleward discrete arc generally having a large longitudinal extent. If the auroral forms are very similar in both hemispheres, then the large longitudinal extent coupled with movement of the auroral could explain why 85% of the PiB events have onsets within 10 min at opposite hemisphere sites (South Pole, Antarctica, and Sondre Stromfjord, Greenland) separated in local magnetic time by about 1.5 hours. There is no seasonal dependence in the statistical occurrence of PiB, nor in its simultaneity in opposite hemispheres. Apparently, the seasonal distortion of the tail plasma sheet has little effect on the acceleration of high-latitude auroral beams. The actual several minute time difference in opposite hemisphere onsets of PiB is probably due to the westward/poleward motion of the longitudinally extended aurora.

• OSTI ID: 5962014
• Journal Information: Journal of Geophysical Research; (United States), Vol. 92:A11; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAE
CHARGED-PARTICLE PRECIPITATION
AURORAL OVAL
HYDROMAGNETIC WAVES
ACCELERATION
CORRELATIONS
EXPANSION
LATITUDE EFFECT
MAGNETIC BAYS
NORTHERN HEMISPHERE
PLASMA SHEET
PULSATIONS
SEASONAL VARIATIONS
SOUTHERN HEMISPHERE
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
EARTH PLANET
GEOGRAPHICAL VARIATIONS
PLANETS
VARIATIONS
661320* - Auroral
Ionospheric
& Magnetospheric Phenomena- (1992-)