The equatorial latitude of auroral activity during 1972–1977

✍ Scribed by N. R. Sheeley; R. A. Howard

• Book ID: 104641225
• Publisher: Springer
• Year: 1980
• Tongue: English
• Weight: 908 KB
• Volume: 67
• Category: Article
• ISSN: 0038-0938
• DOI: 10.1007/bf00146693

✦ Synopsis

The equatorial latitude of auroral activity has been derived from both electron and optical observations with the DMSP satellites. Virtually all of the observations that were obtained during the 5-year interval June 1972-September 1977 have been used to construct a nearly continuous plot of invariant geomagnetic latitude versus time.

This plot has two main characteristics: (1) A diurnal variation of approximately ± 5 ° which is associated with the precession of the Earth's magnetic dipole axis about the Earth's rotation axis; (2) an irregular variation of roughly 5-10 ° for intervals of one to several days associated with the occurrence of solar flares and coronal holes.

With the help of a condensed, Bartels-type display of these measurements, we conclude that: (a) Modest auroral expansions (to A ~ 60 °) occur during the main body of high-speed streams from coronal holes; (b) great expansions (to A < 55 °) occur only during intervals of intense interplanetary magnetic fields such as may occur at the leading edge of a high-speed stream or at a flare-produced interplanetary shock.