Work

Linking Very Near‐Earth Reconnection (VNERX) to Mid‐Latitude GICs: Evidence From the 7 September 2017 Storm

Year: 2025

Type: article

Abstract: Geomagnetically Induced Currents (GICs) are a hazard to power systems. In this letter, we present a case study to understand why a Sudden‐Commencement‐associated 20A GIC spike, measured at mid‐latitude in Virginia, US, increased to 30A within 2 min of interplanetary shock arrival. We use high‐resolution ground magnetometer and in situ satellite data to infer that the shock at 23:00 UT on 7 September 2017 triggered Very‐Near‐Earth Reconnection (VNERX) near dusk. Empirical modeling, using data mining approach, corroborates the occurrence of reconnection within ∼10–12 R E . We argue the preceding interval of southward and westward Interplanetary Magnetic Field enhanced the duskside plasma sheet's susceptibility to VNERX by passage of a nearly frontal shock. To the best of our knowledge, we show for the first time an observational link between inferred‐VNERX and mid‐latitude GIC spike. This finding underscores the complexity a prediction model must capture to accurately predict peak GIC.

Source: Geophysical Research Letters

DOI: 10.1029/2025gl117714

Authors: Bhagyashree Waghule, Delores J. Knipp, Grant K. Stephens, David M. Malaspina

Institutions: University of Colorado Boulder, Johns Hopkins University Applied Physics Laboratory, University of Colorado System, Laboratory for Atmospheric and Space Physics

Language: English

Topic: Ionosphere and magnetosphere dynamics

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $3,190