nerc.ac.uk

GIC at mid-latitudes under extreme Dst scenarios

Kelly, Gemma; Viljanen, Ari; Beggan, Ciaran; Thomson, Alan. 2015 GIC at mid-latitudes under extreme Dst scenarios. [Speech] In: European Space Weather Week 12, Oostende, Belgium, 23-27 Nov 2015. (Unpublished)

Before downloading, please read NORA policies.
[img]
Preview
Text
Kelly_GIC%20in%20UK%20and%20France.pdf

Download (2MB) | Preview

Abstract/Summary

The Dst index is primarily a measure of the magnitude of the equatorial magnetospheric ring current, based on an hourly average of the variation of the Horizontal (H) component from a number of low and mid-latitude ground-based observatories. Extreme values of this index are rare; for example the largest in recent decades occurred during the March 1989 storm, with Dst peaking at -589 nT. Larger values of Dst have been established for the Carrington event – in September 1859 the Bombay observatory recorded a peak of about -850 nT. However, some researchers have suggested that Dst may have been even larger still (-1760 nT), based on one value from Bombay during the 1859 storm. More recent theoretical work has suggested that -2500 nT is the largest possible value physically achievable, given our knowledge of the magnetosphere. Although the ring current variation affects low to mid-latitudes directly, at higher latitudes most variation of H is due to auroral electrojet activity. Motivated by the largest theoretical possible Dst value, we investigate the size of the H variation at high latitudes that might occur during large Dst excursions, by extrapolating relationships observed between H and Dst from previous large storms. To test the consequence of these large H variations we compute the likely GIC in mid-latitude European high-voltage power distribution networks, based on a set of conductivity and grid models of similar complexity, during geomagnetic storms with Dst values of -800, -1700 and -2500 nT.

Item Type: Publication - Conference Item (Speech)
Date made live: 16 Jan 2018 15:53 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/518963

Actions (login required)

View Item View Item

Document Downloads

Downloads for past 30 days

Downloads per month over past year

More statistics for this item...