Accession Number:

AD0723206

Title:

The Origin and Effects of Electric Fields during Isolated Magnetospheric Substorms,

Descriptive Note:

Corporate Author:

CALIFORNIA UNIV BERKELEY SPACE SCIENCES LAB

Personal Author(s):

Report Date:

1971-04-02

Pagination or Media Count:

48.0

Abstract:

Balloon measured electric field data for five hour periods during each of 19 substorms near local midnight between L6.7 and L8.3 have been analyzed and averaged to show that the ionospheric electric field is made up of approximately equal contributions from a large scale field and small scale turbulence. The large scale field in a non-rotating frame of reference develops a westward component during the initial phase of an isolated substorm and an equatorward component about an hour later at the onset of the explosive phase of the substorm. The original of the westward electric field component is related to the connection of southward turning interplanetary magnetic field lines with terrestrial magnetic field lines at the dayside magnetopause, and an example of this causal relationship is presented. The E XB drift of the nightside magnetosphere in response to this westward electric field results in the equatorward drift of auroral arcs, thinning of the plasma sheet development of the tail-like magnetic field geometry on auroral zone magnetic field lines, and many observed ground magnetometer effects. After about an hour, this drift also carries the nightside magnetosphere into an unstable configuration in which drift instabilities deep within the magnetosphere are hypothesized to trigger the explosive phase of the substorm. Author

Subject Categories:

  • Atmospheric Physics
  • Geomagnetism

Distribution Statement:

APPROVED FOR PUBLIC RELEASE