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Research output: Contribution in Book/Report/Proceedings - With ISBN/ISSN › Conference contribution/Paper › peer-review
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TY - GEN
T1 - The distribution and direction of extreme geomagnetic fluctuations over 1-60 minute periods
AU - Rogers, Neil
AU - Wild, Jim
AU - Eastoe, Emma
N1 - Conference code: 33
PY - 2020/10/20
Y1 - 2020/10/20
N2 - We present a statistical climatological study of extreme fluctuations in the horizontal geomagnetic field (dB/dt), generated at the Earth’s surface by extreme electrical currents in the ionosphere and magnetosphere. Applying techniques from Extreme Value Theory we predict the magnitude of |dB/dt| for return periods (RP) from 5 to 500 years. Results presented for both ramp changes and RMS variations over periods from 1–60 minutes show considerable variation in magnitude and rate of occurrence when considered as functions of magnetic latitude, local time, and season. The direction of extreme geomagnetic fluctuations is strongly isotropic at lower latitudes, but this changes with timescale. A technique for improving return level estimates by combining Generalised Pareto tail distributions from discrete directional sectors produces return levels that are higher at low geomagnetic latitudes but higher at mid to high latitudes.
AB - We present a statistical climatological study of extreme fluctuations in the horizontal geomagnetic field (dB/dt), generated at the Earth’s surface by extreme electrical currents in the ionosphere and magnetosphere. Applying techniques from Extreme Value Theory we predict the magnitude of |dB/dt| for return periods (RP) from 5 to 500 years. Results presented for both ramp changes and RMS variations over periods from 1–60 minutes show considerable variation in magnitude and rate of occurrence when considered as functions of magnetic latitude, local time, and season. The direction of extreme geomagnetic fluctuations is strongly isotropic at lower latitudes, but this changes with timescale. A technique for improving return level estimates by combining Generalised Pareto tail distributions from discrete directional sectors produces return levels that are higher at low geomagnetic latitudes but higher at mid to high latitudes.
KW - Geomagnetically induced currents (GIC)
KW - extreme value theory
KW - space weather
U2 - 10.23919/URSIGASS49373.2020.9232328
DO - 10.23919/URSIGASS49373.2020.9232328
M3 - Conference contribution/Paper
SP - 1
EP - 4
BT - 2020 XXXIIIrd General Assembly and Scientific Symposium of the International Union of Radio Science
PB - IEEE
T2 - 33rd URSI General Assembly and Scientific Symposium 2020
Y2 - 29 August 2020 through 5 September 2020
ER -