Estimating the Occurrence of Geomagnetic Activity Using the Hilbert‐Huang Transform and Extreme Value Theory
Abstract In this paper extreme value theory (EVT) has been used to estimate the return levels for geomagnetic activity based on the aa index. The aa index is the longest, continuously recorded, geomagnetic data set (from 1868 to present). This long, 150‐year data set is an ideal candidate for extrem...
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Wiley
2020-08-01
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| Series: | Space Weather |
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| Online Access: | https://doi.org/10.1029/2020SW002513 |
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| author | Sean Elvidge |
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| author_sort | Sean Elvidge |
| collection | DOAJ |
| description | Abstract In this paper extreme value theory (EVT) has been used to estimate the return levels for geomagnetic activity based on the aa index. The aa index is the longest, continuously recorded, geomagnetic data set (from 1868 to present). This long, 150‐year data set is an ideal candidate for extreme value analysis. However, the data are not independent and identically distributed as required for EVT since they are impacted by the approximately 11‐year solar cycle. The Hilbert‐Huang transform has been used to identify the solar cycle component in the data, and the data have been split into solar maximum and minimum times. In these two regimes the generalized extreme value distribution has been fit to the data sets. These have also been combined for an estimate of the overall return times. The results suggest that the largest event in the database (March 1989) is a 1‐in‐25‐year event. However, considering separate solar maximum and minimum times has a large impact on the return times. During solar minimum conditions the return time of the March 1989 event is 130 years. This suggests that the occurrence of extreme space weather events is conditionally dependent on where in the solar cycle we are. |
| format | Article |
| id | doaj-art-bc1ea012a7b947d6ab1bc6479d5469fb |
| institution | Kabale University |
| issn | 1542-7390 |
| language | English |
| publishDate | 2020-08-01 |
| publisher | Wiley |
| record_format | Article |
| series | Space Weather |
| spelling | doaj-art-bc1ea012a7b947d6ab1bc6479d5469fb2025-01-14T16:27:11ZengWileySpace Weather1542-73902020-08-01188n/an/a10.1029/2020SW002513Estimating the Occurrence of Geomagnetic Activity Using the Hilbert‐Huang Transform and Extreme Value TheorySean Elvidge0Space Environment and Radio Engineering Group (SERENE) University of Birmingham Birmingham UKAbstract In this paper extreme value theory (EVT) has been used to estimate the return levels for geomagnetic activity based on the aa index. The aa index is the longest, continuously recorded, geomagnetic data set (from 1868 to present). This long, 150‐year data set is an ideal candidate for extreme value analysis. However, the data are not independent and identically distributed as required for EVT since they are impacted by the approximately 11‐year solar cycle. The Hilbert‐Huang transform has been used to identify the solar cycle component in the data, and the data have been split into solar maximum and minimum times. In these two regimes the generalized extreme value distribution has been fit to the data sets. These have also been combined for an estimate of the overall return times. The results suggest that the largest event in the database (March 1989) is a 1‐in‐25‐year event. However, considering separate solar maximum and minimum times has a large impact on the return times. During solar minimum conditions the return time of the March 1989 event is 130 years. This suggests that the occurrence of extreme space weather events is conditionally dependent on where in the solar cycle we are.https://doi.org/10.1029/2020SW002513extreme value theoryaa indexspace weathergeomagnetic activity |
| spellingShingle | Sean Elvidge Estimating the Occurrence of Geomagnetic Activity Using the Hilbert‐Huang Transform and Extreme Value Theory Space Weather extreme value theory aa index space weather geomagnetic activity |
| title | Estimating the Occurrence of Geomagnetic Activity Using the Hilbert‐Huang Transform and Extreme Value Theory |
| title_full | Estimating the Occurrence of Geomagnetic Activity Using the Hilbert‐Huang Transform and Extreme Value Theory |
| title_fullStr | Estimating the Occurrence of Geomagnetic Activity Using the Hilbert‐Huang Transform and Extreme Value Theory |
| title_full_unstemmed | Estimating the Occurrence of Geomagnetic Activity Using the Hilbert‐Huang Transform and Extreme Value Theory |
| title_short | Estimating the Occurrence of Geomagnetic Activity Using the Hilbert‐Huang Transform and Extreme Value Theory |
| title_sort | estimating the occurrence of geomagnetic activity using the hilbert huang transform and extreme value theory |
| topic | extreme value theory aa index space weather geomagnetic activity |
| url | https://doi.org/10.1029/2020SW002513 |
| work_keys_str_mv | AT seanelvidge estimatingtheoccurrenceofgeomagneticactivityusingthehilberthuangtransformandextremevaluetheory |