Non-typical ground-based quasi-periodic VLF emissions observed at L∼5.3 under quiet geomagnetic conditions at night

Manninen, J.; Клейменова, Н. Г.; Козырева, О. В.; Bespalov, P. A.; Kozlovsky, Alexander

doi:10.1016/j.jastp.2012.05.007

Cited by 41 publications

(38 citation statements)

References 11 publications

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“…QP are classified as Types I and II, depending if they are observed in the presence or absence of geomagnetic pulsations (e.g., Kitamura et al, 1968;Sato & Fukunishi, 1981;Sato et al, 1974). Manninen et al (2013) and Manninen et al (2014) found that the variations of QP periods, particularly their gradual increment, can be explained by the auto-oscillation regime of the cyclotron instability in the magnetosphere. For example, Nėmec et al (2016) show that the time delay between QP simultaneously detected in space and on the ground is related to azimuthally propagating compressional ultra low frequency waves responsible for the generation of the QP.…”

Section: Introductionmentioning

confidence: 99%

Conjugate Observations of Dayside and Nightside VLF Chorus and QP Emissions Between Arase (ERG) and Kannuslehto, Finland

et al. 2020

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We compare for the first time two conjugate events showing simultaneous very low frequency (VLF) wave observations between the same ground station and spacecraft, at different geomagnetic conditions and on opposite sides of the magnetosphere. Waves were observed at Kannuslehto (MLAT = 64.4 • N, L = 5.46), Finland, and on board Arase (Exploration of energization and Radiation in Geospace, ERG) in the inner magnetosphere. Case 1 on 28 March 2017 shows quasiperiodic (QP) emissions and chorus simultaneously observed on the postmidnight side during the recovery phase of a storm, with sustained high solar wind speed and AE index. Case 2 on 30 November 2017 shows clear one-to-one correspondence of QP elements on the noonside during geomagnetic quiet time (Dst > 10 nT and AE < 100 nT). We present the characteristics of both cases, focusing on coherence and spatial extent of the waves, electron density, and magnetic field variations. We report that the magnetic field gradient plays a role in the changes of spectral features of the waves.

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Section: Introductionmentioning

confidence: 99%

Conjugate Observations of Dayside and Nightside VLF Chorus and QP Emissions Between Arase (ERG) and Kannuslehto, Finland

et al. 2020

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“…Some results of the quasi-period VLF emissions analysis have been published in Manninen et al (2012Manninen et al ( , 2013. Furthermore, since the end of 2012, the continuous VLF recordings were started at Lovozero (LOZ) in Russia (ϕ = 67.97 • N, λ = 35.02 • E), located ∼ 400 km to the magnetic east from KAN.…”

Section: Introductionmentioning

confidence: 99%

New results of structured VLF emissions observed simultaneously at two closely located stations near <i>L</i> ~ 5.5

Manninen¹,

Клейменова

Fedorenko

et al. 2014

Ann. Geophys.

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Abstract. Simultaneous records of VLF (very low frequencies) emissions have been carried out at two ground-based stations located at similar geomagnetic latitudes near L ∼ 5.5 and spaced in the longitude by ∼ 400 km, Kannuslehto (KAN) in Finland and Lovozero (LOZ) in Russia, using quite similar VLF receivers with two calibrated orthogonal air-core loop antennas. We found that the general spectral properties of the VLF chorus emissions at these two stations were similar and typically have right-hand polarization. Contrary to VLF chorus, the short-period VLF emissions (periodic emissions, PE) in which separated spectral elements are repeated with the periodicity of 3-4 s were mostly left-hand polarized. Usually, these waves propagated in the north-south direction. We suppose that PEs are generated inside of the plasmasphere by the cyclotron instability under a quasi-linear relaxation of the energetic electron distribution function. However, sometimes PE occurred only at an individual station. We speculated that this could be due to the influence of the local inhomogeneities to the VLF waves during the propagation through the ionospheric trough to the ground. Unusual series of short-duration (10-100 s) bursts of VLF emissions, lasting several hours, were also found in the morning under very quiet geomagnetic conditions (Kp ∼ 0-1). Generally, these emissions were observed simultaneously at KAN and LOZ showing both right-hand and left-hand polarization, and different arrival directions provided the rather extended ionospheric exit area.

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“…55 No. 3 2015 chorus, hiss, and periodic discrete signals (Manninen et al, 2012(Manninen et al, , 2013a(Manninen et al, , 2013b(Manninen et al, , 2014b, usually in the winter.…”

Section: Conditions In Solar Wind and Magnetosphere During The Nontypmentioning

confidence: 99%

“…Unfortu nately, the detection of VLF emissions below 1 kHz is impeded because of the high level of industrial noise. Some results of the analysis of these observations in past years were published in (Manninen et al, 2012(Manninen et al, , 2013a(Manninen et al, , 2013b(Manninen et al, , 2014a(Manninen et al, , 2014b(Manninen et al, , 2014c.…”

Section: Introductionmentioning

confidence: 99%

Conditions in solar wind and magnetosphere during the nontypical VLF hiss burst on December 8, 2013

et al. 2015

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The features of the dynamics of solar wind and IMF parameters were studied during the initial phase of the weak magnetic storm of December 8, 2013, where a nontypical two hour lasting wide band (~4-10 kHz) hiss burst was recorded during VLF observations in auroral latitudes near Sodankyla observatory (L~ 5.5), which differed from classical auroral hiss. A similar VLF hiss burst was recorded at Russian Lovozero obser vatory, which is located ~400 km to the east. In contrast to a typical auroral hiss, the VLF emissions at both points were left polarized and arrived at the observation point from the southeast. Although the VLF hiss burst coincided in time with the development of a substorm and the appearance of zenithal bright auroras near the stations traveling north-south, the excitation of the VLF hiss apparently has no relation to the auro ras. It is suggested that the VLF emissions were generated due to cyclotron instability far to the east of Scan dinavia in the region of plasmapause at L ~ 3.5, where the equatorial gyrofrequency (f He ) is about 20 kHz. The generated VLF waves could be ducted in the plasmapause at frequencies lower than a half of f He , i.e., below ~10 kHz, they arrive at the Earth's surface near the projection of their source and propagate in the Earth-ionosphere waveguide to large distances, as left polarized waves. A sharp increase in the solar wind dynamic pressure was noted during the hiss burst under study, which resulted in a significant contraction of the daytime magnetosphere, a shift of the plasmapause and radiation belt to lower L shells, and the develop ment of a substorm and southward travel of auroral arcs. The VLF hiss may have been generated in the region where energetic particles of the radiation belt crossed the plasmapause. The fact that the hiss under study was generated not in the early morning sector (Scandinavian meridian), but much further to the east, could be indirectly confirmed by quasiperiodic modulation of the VLF noise intensity in the range of Pc5 geomagnetic pulsations, which were observed in this period at eastern stations but not at the Scandinavian meridian.

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Non-typical ground-based quasi-periodic VLF emissions observed at L∼5.3 under quiet geomagnetic conditions at night

Cited by 41 publications

References 11 publications

Conjugate Observations of Dayside and Nightside VLF Chorus and QP Emissions Between Arase (ERG) and Kannuslehto, Finland

Conjugate Observations of Dayside and Nightside VLF Chorus and QP Emissions Between Arase (ERG) and Kannuslehto, Finland

New results of structured VLF emissions observed simultaneously at two closely located stations near <i>L</i> ~ 5.5

Conditions in solar wind and magnetosphere during the nontypical VLF hiss burst on December 8, 2013

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Non-typical ground-based quasi-periodic VLF emissions observed at L∼5.3 under quiet geomagnetic conditions at night

Cited by 41 publications

References 11 publications

Conjugate Observations of Dayside and Nightside VLF Chorus and QP Emissions Between Arase (ERG) and Kannuslehto, Finland

Conjugate Observations of Dayside and Nightside VLF Chorus and QP Emissions Between Arase (ERG) and Kannuslehto, Finland

New results of structured VLF emissions observed simultaneously at two closely located stations near &lt;i&gt;L&lt;/i&gt; ~ 5.5

Conditions in solar wind and magnetosphere during the nontypical VLF hiss burst on December 8, 2013

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New results of structured VLF emissions observed simultaneously at two closely located stations near <i>L</i> ~ 5.5