Five-Minute Solar Oscillations and Ion-Cyclotron Waves in the Solar Wind

Abstract

We study the possible impact of the photospheric five-minute oscillations on the ion-cyclotron waves in the solar wind. We proceed from the assumption that the ioncyclotron waves in the solar wind experience a modulation with a characteristic period of five minutes under the influence of Alfvén waves driven by photospheric motions. The theory presented in this article predicts a deep frequency modulation. This modulation is expected mainly from variations in the orientation of the interplanetary magnetic field lines, which, in turn, are caused by the Alfvén waves propagating from the Sun. To test the theoretical predictions, we analyzed records of the ultra-low-frequency (ULF) geoelectromagnetic waves to find the permanent quasi-monochromatic oscillations of natural origin in the Pc1 -2 frequency band (0.1 -5 Hz), the carrier frequency of which varies with time in a wide range. As a result, we found the so-called serpentine emission (SE), which was observed in Antarctica at the Vostok station near the South Geomagnetic Pole. The permanency, range of frequencies, and the deep frequency modulation of the SE correspond to the qualitative properties of ion-cyclotron waves in the solar wind. In the context of this work, one of the most important features of the SE is a clearly expressed five-minute modulation of the carrier frequency. We assume that we have found non-trivial manifestations of the solar five-minute oscillations on the Earth.

Spectrum of frequency modulation of serpentine emission as a reflection of the solar fluctuation spectrum

“…Furthermore, as inferred from experimental observations of Alfvén waves in near-Earth interplanetary space, there are 5-minute oscillations in their spectrum, which are clearly associated with 5-minute solar oscillations [Potapov et al, 2013]. The question about transformation of 5-minute solar surface oscillations into Alfvén wave energy and their possible contribution to the spectrum of frequency modulation of the serpentine emission has been discussed in detail in [Guglielmi et al, 2015].…”

“…Properties of SE were discussed and refined in [Guglielmi, Dovbnya, 1973, 1974aGuglielmi, 1979;Troitskaya, 1979;Fraser-Smith, 1982;Asheim, 1983;Morris, Cole, 1986, 1987Guglielmi, Pokhotelov, 1996]. One of the newly discovered SE features is that the SE spectrum contains a stable 5-minute carrier modulation lasting a few hours [Guglielmi et al, 2015]. Such an example is shown in Figure 1. B.V. Dovbnya, B.I.…”

Spectrum of frequency modulation of serpentine emission as a reflection of the solar fluctuation spectrum

“…Cвойства SE обсужда-лись и уточнялись в работах [Гульельми, Довбня, 1973Гульельми, 1979;Troitskaya, 1979;Fraser-Smith, 1982;Morris, Cole, 1986. Одна из недавно обнаруженных особенно-стей серпентинной эмиссии состоит в том, что в спектре SE присутствует устойчивая, длящаяся не-сколько часов 5-минутная модуляция несущей ча-стоты [Guglielmi et al, 2015]. Подобный пример по-казан на рис.…”

Waves from the Sun: to the 100th anniversary of V.A. Troitskaya’s birth

“…1. Динамический спектр колебаний Рс1 с глубо-кой модуляцией несущей частоты [Guglielmi et al, 2015] В работе [Guglielmi et al, 2015] приведены аргу-менты в пользу того, что колебания SE постоянно существуют в солнечном ветре, где они самовозбуж-даются в результате ионно-циклотронной неустойчи-вости плазмы, а частотная модуляция SE возникает под влиянием волн Альфвена, испущенных Солнцем. Любопытно, что характерный период частотной мо-дуляции SE равен пяти минутам (см., например, рис.…”

“…Итак, если принять точку зрения, предложен-ную в работе [Guglielmi et al, 2015], то SE пред-ставляет собой ионно-циклотронную волну, моду-лированную по частоте волной Альфвена солнеч-ного происхождения. Мы попытались обнаружить модулирующую волну, используя данные реги-страции УНЧ-колебаний.…”