All Physics Faculty Publications

Document Type

Article

Journal/Book Title/Conference

Journal of Geophysical Research: Space Physics

Volume

95

Issue

A9

Publisher

American Geophysical Union

Publication Date

1990

First Page

15,275

Last Page

15,280

Abstract

The nighttime main F region trough extends into the sunlit afternoon sector. This trough feature exhibits both a strong magnetic activity dependence and a longitude (UT) dependence. Whalen (1987), using International Geophysical Year (IGY) ionosonde data, showed that both of these effects are readily extracted from ƒoF2 observations. In this study we show that the longitude effect is the same as that contained in the Utah State University time-dependent ionospheric model. It arises from the offset of the geomagnetic axis from the geographic axis. The magnetic activity dependency is associated with the westward convection in the afternoon sector. It is also contained in the ionospheric model via the empirical magnetospheric convection model. This one-to-one observational-model agreement is unique; to date no other magnetic activity dependent ionospheric feature has been simulated this systematically.

Comments

Originally published by the American Geophysical Union. Abstract available online through the Journal of Geophysical Research: Space Physics.