Journal cover Journal topic
Natural Hazards and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

IF value: 3.102
IF 5-year value: 3.284
IF 5-year
CiteScore value: 5.1
SNIP value: 1.37
IPP value: 3.21
SJR value: 1.005
Scimago H <br class='widget-line-break'>index value: 90
Scimago H
h5-index value: 42

  12 Apr 2018

12 Apr 2018

Review status: this discussion paper is a preprint. It has been under review for the journal Natural Hazards and Earth System Sciences (NHESS). The manuscript was not accepted for further review after discussion.

Defining scale thresholds for geomagnetic storms through statistics

Judith Palacios, Antonio Guerrero, Consuelo Cid, Elena Saiz, and Yolanda Cerrato Judith Palacios et al.
  • Space Weather Group, Departamento de Física y Matemáticas, Universidad de Alcalá, Alcalá de Henares, Spain

Abstract. Geomagnetic storms, as part of the Sun-Earth relations, are continuously monitored with different indices and scales. These indices usually have some associated scale thresholds to quantify the severity or risk of geomagnetic disturbances. However, the most usual scale thresholds are arbitrarily chosen. In this work we aim to quantify the range of the thresholds through a new method. These new thresholds are based on statistical distribution fitting.

We used different geomagnetic indices, as Dst, SYM-H, and Kp, since they are relevant for space weather purposes. The first two indices have been discriminated between their negative values and the whole dataset. We considered two periods: a short-term one, comprising data from 1997 to 2012; and long-term ones, which are from 1957–2012 for Dst and 1932–2012 for Kp.

We look for the best fit for different statistical continuous distributions applied to these indices. The best fits and the data distribution functions yield to intersects that can be used to define thresholds. The best fit distribution functions are more coincidental between them when considering determined similar datasets, as non-central f-distribution for negative values, meaningful for geomagnetic disturbances; or non-central Student's-t, when the whole dataset is taken. The method yields different values for thresholds depending on the index. Thresholds for geomagnetic storms can be chosen by common values of SYM-H and Dst, as −75 nT for moderate storms; −150 nT for intense storms, and −330 nT for extreme storms. For the case of Kp, the value equal to 5 may mark the departure from quiet time to stormy time.

The obtained values are close to those usually considered as thresholds for, typically, Dst and Kp; therefore the thresholds defined here may provide criteria to assess the vulnerability to geomagnetic activity on design or mitigation purposes.

Judith Palacios et al.

Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Judith Palacios et al.

Judith Palacios et al.


Total article views: 740 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
513 200 27 740 36 26
  • HTML: 513
  • PDF: 200
  • XML: 27
  • Total: 740
  • BibTeX: 36
  • EndNote: 26
Views and downloads (calculated since 12 Apr 2018)
Cumulative views and downloads (calculated since 12 Apr 2018)

Viewed (geographical distribution)

Total article views: 685 (including HTML, PDF, and XML) Thereof 676 with geography defined and 9 with unknown origin.
Country # Views %
  • 1
Latest update: 22 Jan 2021
Publications Copernicus