 |
| Titel |
Extreme value statistics in the solar wind: an application to correlated Lévy processes |
| VerfasserIn |
Jörn Davidsen, Nicholas Moloney |
| Konferenz |
EGU General Assembly 2010
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250038280
|
|
|
|
|
|
| Zusammenfassung |
| The interplay between the solar wind and the Earth’s magnetosphere is a longstanding and
challenging problem. An estimate of the energy influx into the magnetosphere is given by the
Akasofu ε parameter. Extreme values of this parameter are of interest not only for
magnetospheric response, but also for the design of satellites, space stations and
considerations of astronaut safety. For the ε time series derived from ACE spacecraft
measurements for the years 2000 - 2007, we find that its distribution of extreme values over
time windows of about 18 hours and longer can be accurately described by parametric models
based on the mathematical theory of generalized extreme value statistics. These models
predict that significantly larger values than observed to date can be expected during
any 50-year period. While our findings seem to suggest that correlations and/or
non-stationarities do not play a significant role for the extreme value statistics of the
Akasofu ε parameter, we show that the contrary is in fact true. To isolate the effect of
correlations and finite observation periods, we also consider the distribution of
maximal changes in the ε parameter and compare it to the extreme value statistics of
a recently proposed fractional Lévy motion-type model. However, we find that
fractional Lévy motion does not reliably capture the extremal behavior of the ε time
series. |
|
|
|
|
|
|