Auroral bright spot sequence near 1,400 MLT: Coordinated optical and ion drift observations

Journal Article · Sat Dec 01 04:00:00 EST 1990 · Journal of Geophysical Research; (United States)

OSTI ID:5268699

Sandholt, P E; Lybekk, B ^[1]; Lockwood, M; Farmer, A D ^[2]

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1. Univ. of Oslo (Norway)
2. Rutherford Appleton Lab., Chilton (England)

Optical observations of a dayside auroral brightening sequence, by means of all-sky TV cameras and meridian scanning photometers, have been combined with EISCAT ion drift observations within the same invariant latitude - MLT sector. The characteristic intermittent optical events, covering {approximately}300 km in east-west extent, move eastward (antisunward) along the poleward boundary of the persistent background aurora at velocities of {approximately}1.5 in s {sup {minus}1} and are associated with ion flows which swing from eastward to westward, with a subsequent return to eastward, during the interval of a few minutes when there is enhanced auroral emission within the radar field of view. The breakup of discrete auroral forms occurs at the reversal (negative potential) that forms between eastward plasma flow, maximizing near the persistent arc poleward boundary, and strong transient westward flow to the south. These observations are discussed in relation to recent models of boundary layer plasma dynamics and the associated magnetosphere-ionosphere coupling. The ionospheric events may correspond to large-scale wavelike motions of the low-latitude boundary layer (LLBL)/plasma sheet (PS) boundary. On the basis of this interpretation the observed spot size, speed and repetition period ({approximately}10 min) give a wavelength (the distance between spots) of {approximately}900 km in the present case. The events can also be explained as ionospheric signatures of newly opened flux tubes associated with reconnection bursts at the magnetopause near 1,400 MLT. The authors also discuss these data in relation to random, patchy reconnection.

• OSTI ID: 5268699
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 95:A12; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
& Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAE
BOUNDARY LAYERS
DYNAMICS
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELECTROMAGNETIC RADIATION
ENERGY TRANSFER
INTERACTIONS
ION DENSITY
ION DRIFT
IONOSPHERE
LAYERS
MAGNETIC RECONNECTION
MATHEMATICAL MODELS
MEASURING INSTRUMENTS
MECHANICS
MOMENTUM TRANSFER
PHOTOMETERS
PLANETARY IONOSPHERES
PLASMA DRIFT
RADIATIONS
SOLAR ACTIVITY
SOLAR WIND
TRANSIENTS
VISIBLE RADIATION