Challenging the Use of Ring Current Indices During Geomagnetic Storms

Sandhu, Jasmine, Rae, Jonathan and Walach, Maria-Theresia (2021) Challenging the Use of Ring Current Indices During Geomagnetic Storms. Journal of Geophysical Research: Space Physics, 126 (2). e2020JA028423. ISSN 2169-9380

[img]
Preview
Text
2020JA028423.pdf - Published Version
Available under License Creative Commons Attribution 4.0.

Download (4MB) | Preview
[img]
Preview
Text
Manuscript.pdf - Accepted Version
Available under License Creative Commons Attribution 4.0.

Download (3MB) | Preview
Official URL: https://doi.org/10.1029/2020JA028423

Abstract

The ring current experiences dramatic enhancements during geomagnetic storms, however understanding the global distribution of ring current energy content is restricted by spacecraft coverage. Many studies use ring current indices as a proxy for energy content, but these indices average over spatial variations and include additional contributions. We have conducted an analysis of Van Allen Probes’ data, identifying the spatial distribution and storm-time variations of energy content. Ion observations from the HOPE and RBSPICE instruments were used to estimate energy content in L-MLT bins. The results show large enhancements particularly in the premidnight sector during the main phase, alongside reductions in local time asymmetry and intensity during the recovery phase. A comparison with estimated energy content using the Sym-H index was conducted. In agreement with previous results, the Sym-H index significantly overestimates (by up to ∼ 4 times) the energy content, and we attribute the difference to contributions from additional current systems. A new finding is an observed temporal discrepancy, where energy content estimates from the Sym-H index maximise 3 to 9 hours earlier than in situ observations. Case studies reveal a complex relationship, where variable degrees of agreement between the Sym-H index and in situ measurements are observed. The results highlight the drawbacks of ring current indices and emphasise the variability of the storm time ring current.

Item Type: Article
Additional Information: J. K. Sandhu was supported by the NERC Grants NE/P017185/1 and NE/V002554/1. I. J. Rae was supported by the NERC Grants NE/P017185/1 and NE/V002554/1. M.-T. Walach was supported by the NERC Grant NE/P001556/1. Processing and analysis of the HOPE and RBSPICE data were supported by Energetic Particle, Composition, and Thermal Plasma (RBSP-ECT) investigation funded under NASAs Prime contract NAS5-01072.
Uncontrolled Keywords: ring current, geomagnetic storms, Van Allen Probes, Inner magnetosphere, Substorms
Subjects: F300 Physics
F500 Astronomy
Department: Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User: John Coen
Date Deposited: 14 Jan 2021 09:24
Last Modified: 10 Feb 2021 16:45
URI: http://nrl.northumbria.ac.uk/id/eprint/45215

Actions (login required)

View Item View Item

Downloads

Downloads per month over past year

View more statistics