All Physics Faculty Publications

Document Type

Article

Journal/Book Title/Conference

Journal of Geophysical Research: Space Physics

Volume

103

Issue

A9

Publisher

American Geophysical Union

Publication Date

1998

First Page

20,669

Last Page

20,684

DOI

10.1029/98JA01744

Abstract

The results of two ionospheric simulations are compared with each other and with ionospheric observations of the southern hemisphere for the magnetic cloud passage event of January 14, 1988. For most of the event one simulation agrees with observations, while the other does not. Electric fields and electron precipitation patterns generated by a magnetospheric MHD model are used as inputs to a physical model of the ionosphere in the successful simulation, while empirical electric fields and electron precipitation are used as the inputs for the second simulation. In spite of ionospheric summer conditions a large and deep polar hole is developed. This is seen in the in situ plasma observations made by the DMSP-F8 satellite. The hole is surprisingly present during both northward and southward IMF conditions. It is deepest for the storm phase of the southward IMF period. A well-defined tongue of ionization is formed during this period. These features have been reproduced by the TDIM-MHD simulation and to a lesser extent by the TDIM-empirical simulation. However, the model simulations have not been able to generate a storm enhanced density where one was observed by DMSP-F8 during the initial phase of the storm. The differences between the two F region ionospheric simulations are attributed to differences in the magnetospheric electric fields and precipitation patterns used as inputs. This study provides a unique first simulation of the ionosphere's response to self-consistent electric field and auroral precipitation patterns over a 24-hour period that leads into a major geomagnetic storm.

Comments

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

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