Characteristics of variations in the ground magnetic field during substorms at mid latitudes

Turnbull, K.L.; Wild, J.A.; Honary, F.; Thomson, A.W.P.; McKay, A.J.. 2009 Characteristics of variations in the ground magnetic field during substorms at mid latitudes. Annales Geophysicae, 27 (9). 3421-3428.

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Substorms are known to cause geomagnetically induced currents (GIC) in power transmission lines through variations in the ground magnetic field. An improved knowledge and understanding of how the different phases of substorms affect the ground magnetic field will ultimately help to better understand how GIC arise. Although usually associated with high latitude power transmission networks, GIC potentially pose a risk to mid latitude networks such as the UK's National Grid. Using a list of substorm expansion phase onsets derived from auroral observations by the IMAGE-FUV satellite, this study examines 553 individual onsets. In order to cover mid latitudes, ground magnetometer data from the UK Sub-Auroral Magnetometer Network (SAMNET) are exploited. These high time resolution (5 s) data are used to study the ground magnetic field for an hour after onset, in particular the time derivative of the horizontal magnetic field, H. The data covers the period from 2000 to 2003 (just after solar maximum). Results are compared with a previous study of magnetic field variations at higher latitudes, using data with a much lower (1 min) cadence during substorms identified from geomagnetic indices during a period just after solar minimum.

Item Type: Publication - Article
Programmes: BGS Programmes 2009 > Earth hazards and systems
ISSN: 0992-7689
Additional Information. Not used in RCUK Gateway to Research.: Annales Geophysicae (ANGEO) is the official open access journal of the European Geosciences Union (EGU) in the field of Solar Terrestrial Physics.
Date made live: 26 Jan 2010 11:41 +0 (UTC)

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