Geomagnetically Induced Currents at Middle Latitudes: 1. Quiet‐Time Variability

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 se...

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Main Authors: Adam C. Kellerman, Ryan Mcgranaghan, Jacob Bortnik, Brett A. Carter, Joseph Hughes, Robert F. Arritt, Karthik Venkataramani, Charles H. Perry, Jackson McCormick, Chigomezyo M. Ngwira, Morris Cohen, Jia Yue
Format: Article
Language:English
Published: Wiley 2022-02-01
Series:Space Weather
Subjects:
Online Access:https://doi.org/10.1029/2021SW002729
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author Adam C. Kellerman
Ryan Mcgranaghan
Jacob Bortnik
Brett A. Carter
Joseph Hughes
Robert F. Arritt
Karthik Venkataramani
Charles H. Perry
Jackson McCormick
Chigomezyo M. Ngwira
Morris Cohen
Jia Yue
author_facet Adam C. Kellerman
Ryan Mcgranaghan
Jacob Bortnik
Brett A. Carter
Joseph Hughes
Robert F. Arritt
Karthik Venkataramani
Charles H. Perry
Jackson McCormick
Chigomezyo M. Ngwira
Morris Cohen
Jia Yue
author_sort Adam C. Kellerman
collection DOAJ
description 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‐period 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 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.
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spelling doaj-art-bba0c8f8b1f7451fa31a2ae2cd2fe4a12025-01-14T16:30:59ZengWileySpace Weather1542-73902022-02-01202n/an/a10.1029/2021SW002729Geomagnetically Induced Currents at Middle Latitudes: 1. Quiet‐Time VariabilityAdam C. Kellerman0Ryan Mcgranaghan1Jacob Bortnik2Brett A. Carter3Joseph Hughes4Robert F. Arritt5Karthik Venkataramani6Charles H. Perry7Jackson McCormick8Chigomezyo M. Ngwira9Morris Cohen10Jia Yue11Department of Earth, Planetary, and Space Sciences University of California Los Angeles Los Angeles CA USAASTRA LLC Louisville CO USADepartment of Atmospheric and Oceanic Sciences University of California Los Angeles Los Angeles CA USASchool of Science RMIT University Melbourne VIC AustraliaASTRA LLC Louisville CO USATechnical Executive Electric Power Research Institute Knoxville TN USAASTRA LLC Louisville CO USATechnical Executive Electric Power Research Institute Knoxville TN USASchool of Electrical Engineering Georgia Institute of Technology Atlanta GA USAASTRA LLC Louisville CO USASchool of Electrical Engineering Georgia Institute of Technology Atlanta GA USANASA Goddard Space Flight Center Greenbelt MD USAAbstract 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‐period 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 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.https://doi.org/10.1029/2021SW002729GICSqquiet timepower gridmiddle latitudeionospheric current
spellingShingle Adam C. Kellerman
Ryan Mcgranaghan
Jacob Bortnik
Brett A. Carter
Joseph Hughes
Robert F. Arritt
Karthik Venkataramani
Charles H. Perry
Jackson McCormick
Chigomezyo M. Ngwira
Morris Cohen
Jia Yue
Geomagnetically Induced Currents at Middle Latitudes: 1. Quiet‐Time Variability
Space Weather
GIC
Sq
quiet time
power grid
middle latitude
ionospheric current
title Geomagnetically Induced Currents at Middle Latitudes: 1. Quiet‐Time Variability
title_full Geomagnetically Induced Currents at Middle Latitudes: 1. Quiet‐Time Variability
title_fullStr Geomagnetically Induced Currents at Middle Latitudes: 1. Quiet‐Time Variability
title_full_unstemmed Geomagnetically Induced Currents at Middle Latitudes: 1. Quiet‐Time Variability
title_short Geomagnetically Induced Currents at Middle Latitudes: 1. Quiet‐Time Variability
title_sort geomagnetically induced currents at middle latitudes 1 quiet time variability
topic GIC
Sq
quiet time
power grid
middle latitude
ionospheric current
url https://doi.org/10.1029/2021SW002729
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