FG: Understanding the causes of geomagnetic disturbances in geospace for hazard analysis on geomagnetically induced currents

Focus Group Chairs

Xueling Shi, Virginia Tech (xueling7@vt.edu)

Dogacan Su Ozturk, University of Alaska Fairbanks (dsozturk@alaska.edu)

Mark Engebretson, Augsburg University (engebret@augsburg.edu)

Zhonghua Xu, Virginia Tech (zxu77@vt.edu)

Erin Joshua Rigler, USGS (erigler@usgs.gov)

Overview

Geomagnetic disturbances (GMDs) related to various phenomena in the near-Earth space environment can induce geoelectric fields within the electrically conducting Earth. In turn these geoelectric fields drive electric currents that can flow through technological infrastructure in the form of geomagnetically induced currents (GICs) and cause potential damage to power grid, pipelines, and submarine cables. Our focus group (FG) aims to improve the physical understanding of the causes of GMDs through observations, numerical simulations, and machine learning techniques in the solar wind-magnetosphere-ionosphere-ground coupled system for hazard analysis on GICs. Understanding the causes of GMDs is crucial in the development and validation of models which aim to accurately and reliably predict the variations of geoelectric fields and GICs and are objectives of the National Space Weather Strategy and Action Plan (NSWSAP, 2019).

Topic Description

Geomagnetic disturbances (GMDs) have long been used to derive global geomagnetic activity indices (e.g., Kp, AE, and Dst), remote sense the magnetosphere-ionosphere (M-I) currents and plasma waves, and as inputs to geoelectric field/GIC models. The sources of GMDs are directly related to various M-I currents and plasma waves which can be attributed to various drivers in the solar wind-magnetosphere-ionosphere-ground coupled system. Despite extensive research, questions still remain regarding the common sources and driving mechanisms of GMDs. Many studies have focused on the association of GMDs with large-scale geomagnetic activity including storms and substorms. Several more recent statistical studies have analyzed the association of nighttime GMDs with global inputs (IMF and solar wind) and geomagnetic indices (e.g., Engebretson et al., 2021a, 2021b), and case studies have focused on more local phenomena such as overhead ionospheric currents and auroras (Belakhovsky et al., 2019, Dimmock et al., 2019, Apatenkov et al., 2020; and Weygand et al., 2021). The M-I currents that drive nighttime GMDs appear to be linked to mesoscale disturbances in the magnetotail, and their association with substorms and/or intervals of negative IMF Bz suggest the influence of magnetotail reconnection. Up to now, however, there have been very few reports connecting nighttime GMD events to specific disturbances in the magnetotail.

In addition, direct geoelectric field measurements are very limited and GIC measurements are usually not publicly available, many studies rely on dB/dt or ∆B as a proxy. However, it is still not yet well understood whether dB/dt or ∆B is a good proxy of GICs or under what conditions GMDs will couple to extreme geoelectric fields and GICs. Therefore, an interdisciplinary community-wide effort involving the space science data analysis, space weather modelling, magnetotelluric (MT), and the power system engineering communities, is needed to advance our understanding of the causes of GMDs and hazardous GICs. We propose an FG to address the following questions:

Q1: What are the drivers of the formation and evolution of space weather significant GMDs?

Q2: To what extent can different models predict GMDs and what are immediate missing components to improve GMD prediction?

Q3: What is the most important input the GEM community could provide to those who study geoelectric fields and GICs?

2022 GEM Workshop Meeting

Monday, 20 June, 1030-1200 US Hawaii Time, GIC-GBMA Joint Session

The GEM GIC focus group and US magnetometer group will have a joint session at the 2022 GEM workshop. The session will begin with an introduction to both groups followed by an invited talk by Dr. Chigomezyo Ngwira on geomagnetically induced currents and geomagnetic disturbances. The remainder of the session will be for discussion of Solar and Space Physics Decadal Survey white papers related to ground magnetometers and short magnetometer network updates.

• Mike Hartinger, Overview of the US Ground Magnetometer Group
• Xueling Shi, Overview of the new GEM GIC focus group
• Chigomezyo Ngwira (invited), Review of Geomagnetic Disturbances and GIC
• Mike Hartinger, Decadal survey discussions overview, overarching white paper
• Jesper Gjerloev, Decadal survey white paper
• All, Discussion of Decadal survey white papers
• Magnetometer Network/SuperMAG Updates (1-slide each): Jesper Gjerloev (SuperMAG), Shane Coyle (AALPIP), Shane Coyle (GPS Rollover), Michelle Salzano (MICA-S), Hyomin Kim (HamSCI magnetometer), Hyomin Kim (Deep polar cap Antarctic network), Mark Engebretson (MACCS - presenting virtually)

Tuesday, 21 June, 0130-0300 PM US Hawaii Time, GIC Stand-alone Session I

This session will begin with an introduction to the GIC focus group followed by two invited talks and a few contributed talks on observations of GMDs, their potential causes, and education outreach related to magnetometer arrays.

• Xueling Shi, Introduction
• Jeffrey Love (invited), Mapping a magnetic superstorm
• Audrey Schillings (invited), dB/dt spikes during space weather events
• Mark Engebretson, Review of large amplitude geomagnetic disturbances in eastern Arctic Canada
• James Weygand, ASI and GOES observations of nighttime magnetic perturbation events observed in Arctic Canada
• Chigomezyo Ngwira, Analysis of Ground dB/dt Spatiotemporal Variations
• Austin Cohen, UAF Space Weather UnderGround: Space Weather Research and Education Through Student-built Magnetometer Arrays
• Jesper Gjerloev, The MagPi magnetometer: Letting everyone listen to the Earth-Space conversation

Tuesday, 21 June, 0330-0500 PM US Hawaii Time, GIC Stand-alone Session II

This session will focus on geomagnetic and geoelectric field modeling and prediction. It begins with an introduction to current activities of the GIC focus group followed by one invited talk and a few contributed talks on GMD and geoelectric field modeling and prediction. We will have interactive discussion in the end on modeling challenges and future activities of this FG.

• Xueling Shi, Introduction
• Howard Singer (invited), Geospace to Geoelectric Field Modeling at SWPC: Development, Results, and Challenges
• Lisa Winter, Sponsored workshop by NSF-NASA-NOAA
• Shibaji Chakraborty, Modeling Geomagnetic Induction in Submarine Cables
• Elizabeth Vandegriff, Localized Geomagnetic Disturbances: Exploring Modeling and Forecasting Capabilities in Global MHD
• Matthew Blandin, Coupled Model Applications for Geomagnetically Induced Currents across Alaska
• Interactive discussion on modeling challenges.

Friday, 24 June, 1030-1200 US Hawaii Time, IHMIC-GIC Joint Session

• Mark Engebretson, Observations of conjugate high latitude geomagnetic disturbances that can cause GICs
• Zhonghua Xu, Inter-hemispheric asymmetries in the ground magnetic ULF wave response to interplanetary shocks at high latitudes-Case Study
• Hyomin Kim, Magnetosphere-Ionosphere Coupling Studies Using the PSWS Magnetometer Network
• Bob Lysak, Cavity Mode Structure of Pi2 Pulsations
• Martin Archer, What are the ionospheric and ground magnetic signatures of global magnetopause surface modes?
• Simone Di Matteo, Global and local ULF waves in response to solar wind periodic density structures
• Gabby Nowak, Relationship Between Geomagnetic Field Variations and External Drivers Across Different Latitudes and Hemispheres

Friday, 24 June, 0130-0300 PM US Hawaii Time, GIC-IEMIT Joint Session

• Jesper Gjerloev, The NASA EZIE mission: New insight into the Earth-Space electrical current circuit.
• Mike Hartinger, Undersampling of ULF wave fields that drive GIC
• Xueling Shi, Large geoelectric and geomagnetic perturbations observed after an IMF turning and solar wind dynamic pressure impulse
• Thomas Elsden, Modelling the Varying Location of Field Line Resonances During Geomagnetic Storms
• Hannah Parry, Validation of Differential Magnetometer Measurements of GICs on Alberta's High Voltage Network
• Denny Oliveira, Impact Angle Control of Local Intense dB /dt Variations During Shock-Induced Substorms

Friday, 24 June, 0500 pm US Hawaii Time, Honolulu Magnetic observatory field trip (contact Josh: erigler@usgs.gov and Xueling: xueling7@vt.edu to sign up)