| Autor: |
Viljanen Ari, Wintoft Peter, Wik Magnus |
| Jazyk: |
angličtina |
| Rok vydání: |
2015 |
| Předmět: |
|
| Zdroj: |
Journal of Space Weather and Space Climate, Vol 5, p A24 (2015) |
| Druh dokumentu: |
article |
| ISSN: |
2115-7251 |
| DOI: |
10.1051/swsc/2015022 |
| Popis: |
Previous studies have demonstrated a close relationship between the time derivative of the horizontal geomagnetic field vector (dH/dt) and geomagnetically induced currents (GIC) at a nearby location in a power grid. Similarly, a high correlation exists between GIC and the local horizontal geoelectric field (E), typically modelled from a measured magnetic field. Considering GIC forecasting, it is not feasible to assume that detailed prediction of time series will be possible. Instead, other measures summarising the activity level over a given period are preferable. In this paper, we consider the 30-min maximum of dH/dt or E as a local activity indicator (|dH/dt|30 or |E|30). Concerning GIC, we use the sum of currents through the neutral leads at substations and apply its 30-min maximum as a regional activity measure (GIC30). We show that |dH/dt|30 at a single point yields a proxy for GIC activity in a larger region. A practical consequence is that if |dH/dt|30 can be predicted at some point then it is also possible to assess the expected GIC level in the surrounding area. As is also demonstrated, |E|30 and GIC30 depend linearly on |dH/dt|30, so there is no saturation with increasing geomagnetic activity contrary to often used activity indices. |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
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