All Physics Faculty Publications

Document Type

Article

Journal/Book Title/Conference

Journal of Geophysical Research: Space Physics

Volume

104

Issue

A4

Publisher

American Geophysical Union

Publication Date

1999

First Page

6773

Last Page

6781

DOI

10.1029/1998JA900175

Abstract

By using an improved TCV model (Zhu et al., 1997), a quantitative study of the effects of magnetospheric precipitation and ionospheric background conductivity on the ground magnetic signatures of traveling convection vortices (TCVs) has been conducted. In this study the localized conductivity enhancement associated with the TCVs is present and the ratio of the Hall and Pedersen conductances vary both spatially and temporally according to the hardness of the TCV precipitation. It is found that a strong conductivity enhancement associated with hard TCV precipitation can significantly distort the TCV current closure in the ionosphere and lead to ground magnetic disturbance patterns with strong asymmetry in E–W direction. The asymmetry of the ground magnetic patterns is characterized by a stronger magnetic disturbance on the side of the upward field-aligned currents (clockwise convection cell) and a possible rotation of the whole magnetic patterns. Specifically, the modeling results predict that when the characteristic energy of the TCV precipitation is below 500 eV, the asymmetry of the ground magnetic patterns is minimal (less than 1%) and may not be detectable. When the characteristic energy of the precipitation is about 7 keV, the asymmetry of the magnetic patterns can be well above 30%. It is also found that a low ionospheric background conductivity favors the appearance of strong asymmetry in the ground magnetic patterns of the TCVs, while a high ionospheric background conductivity favors the appearance of strong ground magnetic disturbances but with less asymmetry. We concluded that the most favorable condition for the appearance of strong asymmetry in the TCV ground magnetic signatures is the condition of winter, solar minimum, and hard precipitation.

Comments

Originally published by the American Geophysical Union. Publisher's PDF available thorough the Journal of Geophysical Research: Space Physics.

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