High-intensity, long-duration, continuous AE activity events associated with Alfvénic fluctuations in 2003
The interaction between a fast-speed and a low-speed stream causes large-amplitude Alfvénic fluctuations; consequently, the intermittency and the brief intervals of southward magnetic field associated with Alfvén waves may cause high levels of AE activity, the so-called high-intensity, long-dura...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-11-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/35/1231/2017/angeo-35-1231-2017.pdf |
| Summary: | The interaction between a fast-speed and a low-speed stream causes
large-amplitude Alfvénic fluctuations; consequently, the intermittency
and the brief intervals of southward magnetic field associated with Alfvén
waves may cause high levels of AE activity, the so-called high-intensity,
long-duration, continuous AE activity (HILDCAA). In this article, the 4 h
windowed Pearson cross-correlation (4WPCC) between the solar wind velocity
and the interplanetary magnetic field (IMF) components is performed in order
to confirm that the less strict HILDCAA (HILDCAAs*) events include a larger
number of Alfvén waves than the HILDCAA events, once HILDCAAs disregard
part of the phenomenon. Actually, a HILDCAA event is entirely contained within
a HILDCAA* event. However, the opposite is not necessarily true. This article
provides a new insight, since the increase of Alfvén waves results in an
increase of auroral electrojet activity; consequently, it can cause
HILDCAAs* events. Another important aspect of this article is that the
superposed epoch analysis (SEA) results reaffirm that the HILDCAAs* are
associated with high-speed solar streams (HSSs), and also the HILDCAAs*
present the same physical characteristics of the traditional HILDCAA events. |
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| ISSN: | 0992-7689 1432-0576 |