Afternoon auroral spots
email@example.com - last update: 1 July 1996, 1530 UT (RR)
The post-noon reagion (around 14 MLT) seems to have a special significance
in magnetospheric physics. The other
R1 field-aligned current maxima occurs there
(see also Bythrow et al, 1994), and
measurements have shown strong particle precipitation occurring there
(McDiarmid et al., 1975; Evans, 1985).
These relate to a general enhancement of auroral intensity within this
region (Snyder and Akasofu, 1976; Shepherd et al., 1976; Cogger et al., 1977;
Murphree et al., 1981; Meng and Lundin, 1986).
It is possible that this activity is somehow also linked with the nightside
substorm activity (Lui et al., 1987).
The auroral activity consists often of separate bright spots with uniform
spacing, estimated to be about 1.5 hours of local time by Lui et al. (1987).
Similar spots have also been seen in the nightside, and they may correspond
to deformed auroral arcs (folds etc.) when
seen from the ground.
- Bythrow, P. F., B. J. Anderson, T. A. Potemra, L. J. Zanetti, J. D. Winningham,
and D. L. Chenette, Filamentary current structures in the postnoon sector: Observations
from UARS, J. Geophys. Res., 99, 14917-14929, 1994.
- Cogger, L. L., J. S. Murphree, S. Ismail, and C. D. Anger, Characteristics of
dayside 5577 A and 3914 A aurora, Geophys. Res. Lett., 4, 413, 1977.
- Evans, D. S., The characteristics of a persistent auroral arc at high
latitude in the 1400 MLT sector, in The Polar Cusp, edited by J. A. Holtet
and A. Egeland, p. 99, D. Reidel Pub. Co., Dordrecht, Holland, 1985.
- Lui, A. T. Y., D. Venkatesan, and J. S. Murphree, Auroral bright spots on the
dayside oval, J. Geophys. Res., 94, 5515-5522, 1989.
- McDiarmid, I. B., J. R. Burrows, and E. E. Budzinski, Average characteristics
of magnetospheric electrons (150 eV to 300 keV) at 1400 km, J. Geophys. Res.,
80, 73, 1975.
- Murphree, J. S., L. L. Cogger, and C. D. Anger, Characteristics of the
instantaneous oval in 1200.1800 MLT sector, J. Geophys. Res., 86,
- Shepherd, G. G., F. W. Thirkettle, and C. D. Anger, Topside optical view of
the dayside cleft aurora, Planet. Space Sci., 24, 937, 1976.
- Snyder, A. L., and S.-A. Akasofu, Auroral oval photographs from the
DMSP 8531 and 10533 satellites, J. Geophys. Res., 81, 1799, 1976.