An atlas of VLF emission spectra observed with the Hiss recorder

Koch, Jean A.

doi:10.6028/nbs.tn.226

Cited by 3 publications

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“…Watts et al [1963] obtained very impressive records of audio frequency hiss, and they published a number of examples with their description of the instrument. Koch and Edens [1964] subsequently published an atlas of records obtained with this instrument at a wide variety of locations including simultaneous observations at conjugate locations.…”

Section: Wide-band Hiss Recordermentioning

confidence: 78%

Wide-band observations of lf hiss at Frobisher Bay (L= 14.6)

Morgan

1977

J. Geophys. Res.

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LF hiss was recorded at Frobisher Bay (L = 14.6, Λ ≃ 75°) during the 1‐year periods October 30, 1971, to November 18, 1972, and June 27, 1974, to June 26, 1975, by using a wide‐band receiver covering 0–100 kHz. A sweeping narrow‐band recorder produced intensity‐modulated frequency‐versus‐time records which show the spectral and temporal variations of the hiss. The hiss occurs in bursts of approximately 1‐ to 30‐min duration. Nearly all of the bursts have a minimum bandwidth of at least 30 kHz centered in the 20‐ to 30‐kHz range. Many extend upward to 100 kHz, showing increasing intensity with increasing frequency. Few extend downward below 10 kHz, and those that do show decreasing intensity. A single strong diurnal peak of occurrence is found centered on 21 hours local magnetic time. During the second year a rapid response 30‐MHz riometer was operated with the LF hiss recorder, and a direct association of some riometer events with some hiss events was found, the hiss event occurring just before, or just at the onset of, the riometer event. However, strong riometer events with rapid onset can occur with no accompanying hiss, and strong hiss bursts can occur with no accompanying riometer absorption. The results are discussed in the context of other hiss observations on the ground and in the topside ionosphere and their correlation with fluxes of particle precipitation.

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Section: Wide-band Hiss Recordermentioning

confidence: 78%

Wide-band observations of lf hiss at Frobisher Bay (L= 14.6)

Morgan

1977

J. Geophys. Res.

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“…Quasiperiodic (QP) emissions (Helliwell, 1965), also known “long‐period emissions” (Carson et al., 1965), are Extremely Low Frequency/Very Low Frequency (ELF/VLF, ∼10s Hz to ∼10 kHz) whistler‐mode waves that are characterized by a quasiperiodic modulation of wave intensity. This modulation typically exhibits a periodicity from 10 s to 10 min (Brice, 1965; Helliwell, 1965; Helliwell & Brice, 1964; Kitamura, 1968; Koch & Edens, 1964) which may vary smoothly over space and time (Hayosh et al., 2014; Helliwell, 1965). They occur in a frequency range from 0.5 to 10 kHz, and may exhibit a rising‐tone structure as observed in the frequency‐time spectrum (Carson et al., 1965).…”

Section: Introductionmentioning

confidence: 99%

Multipoint Observations of Quasiperiodic Emission Intensification and Effects on Energetic Electron Precipitation

Bortnik

et al. 2021

JGR Space Physics

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The two Van Allen Probes simultaneously recorded a coherently modulated quasiperiodic (QP) emission that persisted for 3 h. The magnetic field pulsation at the locations of the two satellites showed a substantial difference, and their frequencies were close to but did not exactly match the repetition frequency of QP emissions for most of the time, suggesting that those coherent QP emissions probably originated from a common source, which then propagated over a broad area in the magnetosphere. The QP emissions were amplified by local anisotropic electron distributions, and their large‐scale amplitudes were modulated by the plasma density. A novel observation of this event is that chorus waves at frequencies above QP emissions exhibit a strong correlation with QP emissions. Those chorus waves intensified when the QP emissions reach their peak frequency. This indicates that embryonic QP emissions may be critical for its own intensification as well as chorus waves under certain circumstances. A Low‐Earth‐Orbit POES satellite observed enhanced energetic electron precipitation in conjunction with the Van Allen Probes, providing direct evidence that QP emissions precipitate energetic electrons into the atmosphere. This scenario is quantitatively confirmed by our quasilinear diffusion simulation results.

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“…However, until a continuously recording VLF receiver with sufficient time compression (known as a hiss recorder) [Watts et al, 1963] was put into operation, the phenomenon now known as 'long period VLF pulsations' escaped the notice of observers. Since that time, observations of longperiod VLF emission events have been made on many occasions over a wide range of latitudes [Koch and Edens, 1964]. Consequently, it is now possible to define the phenomenon and distinguish it from short-period VLF pulsations as being not merely different in degree but different in kind.…”

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confidence: 99%

Long-period very low frequency emission pulsations

Carson¹,

Koch²,

Pope³

et al. 1965

J. Geophys. Res.

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Pulse trains with periods of the order of a minute occur in the natural VLF signals emitted in the exosphere. Composed of otherwise ordinary VLF emissions, the long‐period pulses always rise in frequency. At magnetically conjugate points the long‐period pulse signals are received simultaneously. The period of the pulsation events exhibits a latitude dependence, becoming longer at higher latitudes. On the basis of available data, a hypothesis associating hydromagnetic waves with emitting particles is offered to account for the observed properties of the pulsations.

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An atlas of VLF emission spectra observed with the Hiss recorder

Abstract: B S<2 pi z c s c g-p g4 > °°.

Cited by 3 publications

References 0 publications

Wide-band observations of lf hiss at Frobisher Bay (L= 14.6)

Wide-band observations of lf hiss at Frobisher Bay (L= 14.6)

Multipoint Observations of Quasiperiodic Emission Intensification and Effects on Energetic Electron Precipitation

Long-period very low frequency emission pulsations

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