Associating ground magnetometer observations with current or voltage generators

Document Type

Article

Publication Date

7-1-2017

Abstract

A circuit analogy for magnetosphere-ionosphere current systems has two extremes for drivers of ionospheric currents: ionospheric electric fields/voltages constant while current/conductivity vary—the “voltage generator”—and current constant while electric field/conductivity vary—the “current generator.” Statistical studies of ground magnetometer observations associated with dayside Transient High Latitude Current Systems (THLCS) driven by similar mechanisms find contradictory results using this paradigm: some studies associate THLCS with voltage generators, others with current generators. We argue that most of this contradiction arises from two assumptions used to interpret ground magnetometer observations: (1) measurements made at fixed position relative to the THLCS field-aligned current and (2) negligible auroral precipitation contributions to ionospheric conductivity. We use observations and simulations to illustrate how these two assumptions substantially alter expectations for magnetic perturbations associated with either a current or a voltage generator. Our results demonstrate that before interpreting ground magnetometer observations of THLCS in the context of current/voltage generators, the location of a ground magnetometer station relative to the THLCS field-aligned current and the location of any auroral zone conductivity enhancements need to be taken into account.

Identifier

85021733167 (Scopus)

Publication Title

Journal of Geophysical Research Space Physics

External Full Text Location

https://doi.org/10.1002/2017JA024140

e-ISSN

21699402

ISSN

21699380

First Page

7130

Last Page

7141

Issue

7

Volume

122

Grant

1443507

Fund Ref

National Science Foundation

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