Skip to content Skip to navigation
University of Warwick
  • Study
  • |
  • Research
  • |
  • Business
  • |
  • Alumni
  • |
  • News
  • |
  • About

University of Warwick
Publications service & WRAP

Highlight your research

  • WRAP
    • Home
    • Search WRAP
    • Browse by Warwick Author
    • Browse WRAP by Year
    • Browse WRAP by Subject
    • Browse WRAP by Department
    • Browse WRAP by Funder
    • Browse Theses by Department
  • Publications Service
    • Home
    • Search Publications Service
    • Browse by Warwick Author
    • Browse Publications service by Year
    • Browse Publications service by Subject
    • Browse Publications service by Department
    • Browse Publications service by Funder
  • Help & Advice
University of Warwick

The Library

  • Login
  • Admin

Variation of geomagnetic index empirical distribution and burst statistics across successive solar cycles

Tools
- Tools
+ Tools

Bergin, Aisling, Chapman, Sandra C., Moloney, N. R. and Watkins, Nicholas W. (2022) Variation of geomagnetic index empirical distribution and burst statistics across successive solar cycles. Journal of Geophysical Research: Space Physics, 127 (1). e2021JA029986. doi:10.1029/2021ja029986

[img]
Preview
PDF
WRAP-variation-geomagnetic-index-empirical-distribution-burst-statistics-across-successive-solar-cycles-2022.pdf - Published Version - Requires a PDF viewer.
Available under License Creative Commons Attribution 4.0.

Download (2456Kb) | Preview
Official URL: https://doi.org/10.1029/2021ja029986

Request Changes to record.

Abstract

The overall level of solar activity, and space weather response at Earth, varies within and between successive solar cycles and can be characterized by the statistics of bursts, i.e., time series excursions above a threshold. We consider nonoverlapping 1‐year samples of the auroral electrojet index (AE) and the SuperMAG‐based ring current index (SMR), across the last four solar cycles. These indices, respectively, characterize high latitude and equatorial geomagnetic disturbances. We suggest that average burst duration τ ̄ $\bar{\tau }$ and burst return period R ̄ $\bar{R}$ form an activity parameter, τ ̄ / R ̄ $\bar{\tau }/\bar{R}$ which characterizes the fraction of time the magnetosphere spends, on average, in an active state for a given burst threshold. If the burst threshold takes a fixed value, τ ̄ / R ̄ $\bar{\tau }/\bar{R}$ for SMR tracks sunspot number, while τ ̄ / R ̄ $\bar{\tau }/\bar{R}$ for AE peaks in the solar cycle declining phase. Level crossing theory directly relates τ ̄ / R ̄ $\bar{\tau }/\bar{R}$ to the observed index value cumulative distribution function (cdf). For burst thresholds at fixed quantiles, we find that the probability density functions of τ and R each collapse onto single empirical curves for AE at solar cycle minimum, maximum, and declining phase and for (−)SMR at solar maximum. Moreover, underlying empirical cdf tails of observed index values collapse onto common functional forms specific to each index and cycle phase when normalized to their first two moments. Together, these results offer operational support to quantifying space weather risk which requires understanding how return periods of events of a given size vary with solar cycle strength.

Item Type: Journal Article
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Faculty of Science > Physics
SWORD Depositor: Library Publications Router
Library of Congress Subject Headings (LCSH): Space environment, Magnetospheric physics, Ionosphere, Solar cycle, Geomagnetic indexes
Journal or Publication Title: Journal of Geophysical Research: Space Physics
Publisher: Wiley-Blackwell Publishing, Inc.
ISSN: 2169-9380
Official Date: 18 January 2022
Dates:
DateEvent
18 January 2022Published
24 December 2021Accepted
Volume: 127
Number: 1
Article Number: e2021JA029986
DOI: 10.1029/2021ja029986
Status: Peer Reviewed
Publication Status: Published
Access rights to Published version: Open Access
RIOXX Funder/Project Grant:
Project/Grant IDRIOXX Funder NameFunder ID
FA9550-17-1-0054Air Force Office of Scientific Researchhttp://dx.doi.org/10.13039/100000181
FA8655-22-1- 7056Air Force Office of Scientific Researchhttp://dx.doi.org/10.13039/100000181

Request changes or add full text files to a record

Repository staff actions (login required)

View Item View Item

Downloads

Downloads per month over past year

View more statistics

twitter

Email us: wrap@warwick.ac.uk
Contact Details
About Us