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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 35, issue 6 | Copyright

Special issue: Space weather connections to near-Earth space and the...

Ann. Geophys., 35, 1231-1240, 2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.

Regular paper 13 Nov 2017

Regular paper | 13 Nov 2017

High-intensity, long-duration, continuous AE activity events associated with Alfvénic fluctuations in 2003

Alan Prestes, Virginia Klausner, and Arian Ojeda-González Alan Prestes et al.
  • Vale do Paraiba University – UNIVAP 12244-000, São José dos Campos, SP, Brazil

Abstract. 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 4h 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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