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- Title
Extreme geomagnetically induced currents.
- Authors
Kataoka, Ryuho; Ngwira, Chigomezyo
- Abstract
We propose an emergency alert framework for geomagnetically induced currents (GICs), based on the empirically extreme values and theoretical upper limits of the solar wind parameters and of d B/d t, the time derivative of magnetic field variations at ground. We expect this framework to be useful for preparing against extreme events. Our analysis is based on a review of various papers, including those presented during Extreme Space Weather Workshops held in Japan in 2011, 2012, 2013, and 2014. Large-amplitude d B/d t values are the major cause of hazards associated with three different types of GICs: (1) slow d B/d t with ring current evolution (RC-type), (2) fast d B/d t associated with auroral electrojet activity (AE-type), and (3) transient d B/d t of sudden commencements (SC-type). We set 'caution,' 'warning,' and 'emergency' alert levels during the main phase of superstorms with the peak Dst index of less than −300 nT (once per 10 years), −600 nT (once per 60 years), or −900 nT (once per 100 years), respectively. The extreme d B/d t values of the AE-type GICs are 2000, 4000, and 6000 nT/min at caution, warning, and emergency levels, respectively. For the SC-type GICs, a 'transient alert' is also proposed for d B/d t values of 40 nT/s at low latitudes and 110 nT/s at high latitudes, especially when the solar energetic particle flux is unusually high.
- Subjects
SOLAR wind; MAGNETIC fields; HAZARDS; ELECTROJETS; SOLAR energetic particles
- Publication
Progress in Earth & Planetary Science, 2016, Vol 3, Issue 1, p1
- ISSN
2197-4284
- Publication type
Article
- DOI
10.1186/s40645-016-0101-x