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Challenging the Use of Ring Current Indices During Geomagnetic Storms

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Challenging the Use of Ring Current Indices During Geomagnetic Storms. / Sandhu, J. K.; Rae, I. J; Walach, Maria.
In: Journal of Geophysical Research: Space Physics, Vol. 126, No. 2, e2020JA028423, 28.02.2021.

Research output: Contribution to Journal/MagazineJournal articlepeer-review

Harvard

Sandhu, JK, Rae, IJ & Walach, M 2021, 'Challenging the Use of Ring Current Indices During Geomagnetic Storms', Journal of Geophysical Research: Space Physics, vol. 126, no. 2, e2020JA028423. https://doi.org/10.1029/2020JA028423

APA

Sandhu, J. K., Rae, I. J., & Walach, M. (2021). Challenging the Use of Ring Current Indices During Geomagnetic Storms. Journal of Geophysical Research: Space Physics, 126(2), Article e2020JA028423. https://doi.org/10.1029/2020JA028423

Vancouver

Sandhu JK, Rae IJ, Walach M. Challenging the Use of Ring Current Indices During Geomagnetic Storms. Journal of Geophysical Research: Space Physics. 2021 Feb 28;126(2):e2020JA028423. Epub 2021 Jan 13. doi: 10.1029/2020JA028423

Author

Sandhu, J. K. ; Rae, I. J ; Walach, Maria. / Challenging the Use of Ring Current Indices During Geomagnetic Storms. In: Journal of Geophysical Research: Space Physics. 2021 ; Vol. 126, No. 2.

Bibtex

@article{31f156016aeb4e979916f43495d27d66,
title = "Challenging the Use of Ring Current Indices During Geomagnetic Storms",
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{\textquoteright} 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.",
keywords = "ring current, geomagnetic storms, Van Allen Probes, Inner magnetosphere, Substorms",
author = "Sandhu, {J. K.} and Rae, {I. J} and Maria Walach",
year = "2021",
month = feb,
day = "28",
doi = "10.1029/2020JA028423",
language = "English",
volume = "126",
journal = "Journal of Geophysical Research: Space Physics",
issn = "2169-9402",
publisher = "Blackwell Publishing Ltd",
number = "2",

}

RIS

TY - JOUR

T1 - Challenging the Use of Ring Current Indices During Geomagnetic Storms

AU - Sandhu, J. K.

AU - Rae, I. J

AU - Walach, Maria

PY - 2021/2/28

Y1 - 2021/2/28

N2 - 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.

AB - 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.

KW - ring current

KW - geomagnetic storms

KW - Van Allen Probes

KW - Inner magnetosphere

KW - Substorms

U2 - 10.1029/2020JA028423

DO - 10.1029/2020JA028423

M3 - Journal article

VL - 126

JO - Journal of Geophysical Research: Space Physics

JF - Journal of Geophysical Research: Space Physics

SN - 2169-9402

IS - 2

M1 - e2020JA028423

ER -