Preprints
https://doi.org/10.5194/angeo-2020-65
https://doi.org/10.5194/angeo-2020-65

  12 Oct 2020

12 Oct 2020

Review status: a revised version of this preprint was accepted for the journal ANGEO and is expected to appear here in due course.

A case study of the spectral parameters of ULF fluctuations before substorms with no evident trigger in the interplanetary space

Nataliya Sergeevna Nosikova1,2, Nadezda Viktorovna Yagova2, Lisa Jane Baddeley3, Dag Arne Lorentzen3, and Dmitriy Anatolyevich Sormakov4 Nataliya Sergeevna Nosikova et al.
  • 1National Nuclear University “MEPhI”, Moscow, Russia
  • 2Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences (IPE RAS), Moscow, Russia
  • 3University Center on Svalbard, Norway
  • 4Arctic and Antarctic Research Institute, AARI, Geophysics department, Sankt-Petersburg, Russia

Abstract. Our recent study (Yagova et al., 2017) shows that ultralow frequency (ULF) pulsations are seen in ground-based magnetic and luminosity data in the polar cap for a few hours preceding isolated non-triggered substorms. Such pulsations are characterised by a high level of coherence. There might be two possible origins of these pulsations: ULF disturbances in the solar wind or processes inside the magnetosphere, which lead to a substorm generation. In this case, the first scenario should be considered as a substorm trigger. To understand the role of the mentioned mechanisms in developing of pulsations, a detailed case study has been carried out. It is shown that before a weak substorm, fluctuations with the central frequency 1.5 mHz are observed in the both polar caps in ground-based geomagnetic data. Coherent pulsations with the same main frequency are also seen in the magnetotail magnetic field, in addition to simultaneous electron concentration in the ionosphere, while fluctuations in electron temperature and electron flux in the magnetosphere have a slightly different main frequency. These pulsations appeared after ULF activity in solar wind and interplanetary magnetic field became inappreciable.

Nataliya Sergeevna Nosikova et al.

 
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Status: closed
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Nataliya Sergeevna Nosikova et al.

Nataliya Sergeevna Nosikova et al.

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