loading page

Geomagnetically Induced Currents at Middle Latitudes: 1. Quiet-time Variability
  • +9
  • Adam C Kellerman,
  • Ryan Michael McGranaghan,
  • Jacob Bortnik,
  • Brett Anthony Carter,
  • Joseph Hughes,
  • Robert Arritt,
  • Karthik Venkataramani,
  • Charles H Perry,
  • Jackson C McCormick,
  • Chigomezyo M Ngwira,
  • Morris B. Cohen,
  • Jia Yue
Adam C Kellerman
University of California Los Angeles, University of California Los Angeles

Corresponding Author:[email protected]

Author Profile
Ryan Michael McGranaghan
Atmosphere and Space Technology Research Associates, Atmosphere and Space Technology Research Associates
Author Profile
Jacob Bortnik
University of California Los Angeles, University of California Los Angeles
Author Profile
Brett Anthony Carter
RMIT University, RMIT University
Author Profile
Joseph Hughes
Atmosphere and Space Technology Research Associates, Atmosphere and Space Technology Research Associates
Author Profile
Robert Arritt
EPRI, EPRI
Author Profile
Karthik Venkataramani
Atmospheric and Space Technology Research Associates, Atmospheric and Space Technology Research Associates
Author Profile
Charles H Perry
EPRI, EPRI
Author Profile
Jackson C McCormick
Georgia Institute of Technology, Georgia Institute of Technology
Author Profile
Chigomezyo M Ngwira
Atmospheric and Space Technology Research Associates, Atmospheric and Space Technology Research Associates
Author Profile
Morris B. Cohen
Georgia Institute of Technology, Georgia Institute of Technology
Author Profile
Jia Yue
Goddard Space Flight Center, Goddard Space Flight Center
Author Profile

Abstract

Geomagnetically induced currents (GICs) at middle latitudes have received increased attention after reported power-grid disruptions due to geomagnetic disturbances. However, quantifying the risk to the electric power grid at middle latitudes is difficult without understanding how the GIC sensors respond to geomagnetic activity on a daily basis. Therefore, in this study the question “Do measured GICs have distinguishable and quantifiable long- and short-period characteristics?” is addressed. The study focuses on the long-term variability of measured GIC, and establishes the extent to which the variability relates to quiet-time geomagnetic activity. GIC quiet-day curves (QDCs) are computed from measured data for each GIC node, covering all four seasons, and then compared with the seasonal variability of Thermosphere-Ionosphere- Electrodynamics General Circulation Model (TIE-GCM)-simulated neutral wind and height-integrated current density. The results show strong evidence that the middle-latitude nodes routinely respond to the tidal-driven Sq variation, with a local time and seasonal dependence on the the direction of the ionospheric currents, which is specific to each node. The strong dependence of GICs on the Sq currents demonstrates that the GIC QDCs may be employed as a robust baseline from which to quantify the significance of GICs during geomagnetically active times and to isolate those variations to study independently. The QDC-based significance score computed in this study provides power utilities with a node-specific measure of the geomagnetic significance of a given GIC observation. Finally, this study shows that the power grid acts as a giant sensor that may detect ionospheric current systems.
Feb 2022Published in Space Weather volume 20 issue 2. 10.1029/2021SW002729