Global auroral responses to magnetospheric compressions by shocks in the solar wind: two case studies
Two case studies are presented of the global auroral responses to shocks in the solar wind at Earth. The z component of the interplanetary magnetic field, Bz, is negative ahead and behind the first shock and positive for the second case. A sudden-commencement geomagnetic storm develops in each case, with maximum D/sub st/ < or = 190 nT. An immediate auroral response is detected at all longitudes around the auroral oval, in which auroral luminosities increase by a factor of 2 to 3 with the first samples after each sudden commencement. The time delay in obtaining the first sample varies with local time from approx 1 to 18 minutes. No other significant variations in the aurorae are associated with the immediate response. Beginning about 30 minutes after each sudden commencement, the aurorae become active and display significant variations in luminosity and spatial distribution. For B/sub z/ < 0 an intense substorm develops. A sun-aligned transpolar arc forms when B/sub z/ > 0, appearing first at local midnight as a polar arc and then lengthening sunward from the auroral oval across the polar cap to noon at an average speed of about 1 km/sec.
- Research Organization:
- Iowa Univ., Iowa City (USA). Dept. of Physics and Astronomy
- OSTI ID:
- 6699794
- Report Number(s):
- AD-A-175734/3/XAB
- Resource Relation:
- Other Information: Published in Geophysical Research Letters, Vol. 13, No. 8, 873-876(1986); Original contains color plates: All DTIC and NTIS reproductions will be in black and white
- Country of Publication:
- United States
- Language:
- English
Similar Records
Diagnosis of auroral dynamics using global auroral imaging with emphasis on large-scale evolutions
Intensification and fading of auroral arcs in the dusk-midnight sector of the polar cap
Related Subjects
GENERAL PHYSICS
AURORAE
LUMINOSITY
EARTH MAGNETOSPHERE
SOLAR WIND
MAGNETIC STORMS
SUDDEN COMMENCEMENTS
COMPRESSION
INTERPLANETARY SPACE
MAGNETIC FIELDS
SAMPLING
SPATIAL DISTRIBUTION
DISTRIBUTION
EARTH ATMOSPHERE
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
SOLAR ACTIVITY
SPACE
640201* - Atmospheric Physics- Auroral
Ionospheric
& Magetospheric Phenomena