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# Polarization and arriving direction of VLF emissions by Masanori Nishino

Published by Dept. of Polar Research, National Science Museum in Tokyo .

Written in English

• Antarctica.

## Subjects:

• VLF emissions -- Antarctica.

Edition Notes

Bibliography: p. 14.

## Book details

Classifications The Physical Object Statement [by] Masanori Nishino and Yoshito Tanaka. Series JARE scientific reports. Series A, no. 7 Contributions Tanaka, Yoshito, 1937- joint author. LC Classifications QC879 .N54 no. 7, QC973.4.V2 .N54 no. 7 Pagination 14 p. Number of Pages 14 Open Library OL5117869M LC Control Number 74190823

Polarization and direction of arrival of VLF emissions have been observed at Syowa Station in the Antarctic by a combination of a vertical antenna and a crossed loop antenna with their planes oriented in geomagnetic E-W and N-S : Masanori Nishino and Yoshito Tanaka.

been pitch angle scattered by individual chorus emission packets. VLF perturbation finding measurements of the arrival direction of chorus or other magnetospheric emissions. Carpenter [] per- angle and the general elliptical polarization of each ray.

The field analysis direction finding is such that the four parameters (incident (i) and azimuthal (0) angles and the wave polarization (u, v)) are deduced from the amplitude ratios and phase differences among z (Zenith) y (North) PRECURSORY RADIO EMISSIONS ASSOCIATED WITH EARTHQUAKES I) -u E J.S.T Jan, (YAMAOKA) Fig.

by:   The VLF equipment installed at each station has three major functions (Tanaka et al., ): (l) Continuous recording of the intensity of hiss-type emissions at 5 and 3 kHz by means of hiss recor- ders, (2) continuous recording of the arrival angle and polarization of VLF emissions at 5 kHz, and (3) synoptic 2-minutes' sampling goniometer meas Cited by:   Contrary to VLF chorus, the short-period VLF emissions (periodic emissions, PE) in which separated spectral elements are repeated with the periodicity of s were mostly left-hand polarized.

Usually, these waves propagated in the north-south by: 6. Attempts to measure the arrival direction of whistlers and associated VLF waves were initiated during the period of the IGY. Watt () was the first to use the goniometer method and showed that *Now at Research Institute of Atmospherics, Nagoya University, Japan.

some whistlers exhibited nulls when the goniometer was rotated. However, the polarization of the incident wave changes at the reflection since the ground surface does not act as a perfect conductor for VLF waves, (b) Whistlers and VLF emissions are by no means mono- chromatic and consist of waves with different frequencies and different phases, (c) Reflection of the wave also occurs at the ionosphere.

The polarization ellipse technique has previously been applied to broadband signals to locate the arrival direction of chorus signals reentering the atmosphere from the space environment at high latitudes (Gołkowski & Inan, ; Poorya et al., ), as well as for direction finding of broadband sferics (Said et al., ).

We find that the received magnetic ELF/VLF waves can be decomposed into two circularly polarized modes (R and L) with comparable strengths, and the Polarization and arriving direction of VLF emissions book ellipse lies approximately in North-South direction (parallel to the background electric field), which is similar to the recognized features of AM generated ELF/VLF waves originated from D/E-region ionosphere.

The wave arrival direction and polarization are determined through measurement of the ratio of the amplitudes and phase difference of the magnetic components to the vertical electric component.

Rapid growth of radio emission sources (RES) leads to the interference of signals from various transceivers and thus complicates its positioning based on direction finding (DF).

Traditional DF use structural-statistical redundancy to resolve multi-signal and multipath situations, which makes impossible to implement it in compact direction finders.

wave polarization (u, v). This determination of the arrival direction will be called the B method because we utilize the imaginary parts (b1 and b2) for the determination ofφ. 〔Case 2 ("A" method)〕 The quantities bl and b2 are both zero, implying that either i=90° or v is zero (linear polarization).

JARE SCIENTIFIC REPORTS SERIES A NO. 7 Polarization and Arriving Direction of VLF Emissions Masanori NISHINO and Yoshito TANAKA (The Research Institute of Atmospherics, Nagoya University, Toyokawa) DEPARTMENT OF POLAR RESEARCH NATIONAL SCIENCE MUSEUM.

We have analyzed a unique 2 h observation with concurrent hiss, chorus, VLF triggered emissions, and local HAARP‐generated ELF/VLF signals. Using calculated eccentricity of polarization as a novel filter, we show that the observations show a common ionospheric exit point for different types of magnetospheric emissions that can be tracked in time.

KOKUBUN, S. et al.: VLF emissions study at Syowa Station, Antarctica-Polar chorus emission and worldwide geomagnetic variation. March N1sH1No, M. and TANAKA, Y.: Polarization and arriving direction of VLF emissions. July HIRASAWA, T. and KAMINUMA, K.: Spacc: time variation of aurora and geomagnetic.

The physical parameters (polarization and direction of arrival) of the incoming wave are related to the received voltages on the antenna system by the so-called direction-finding equations. With the beam pattern of the FORTE antennas, the arriving polarization circle will be foreshortened toward an ellipse.

The measured ε depends predominantly on the angle away from the satellite's nadir, and slightly on the angle of azimuth referenced to the satellite's ram direction, as viewed from the satellite.

Polarization was defined as P = B r /B θ, where B r is the radial complex valued magnetic field component in the direction from HAARP to receiver and B θ is the horizontal magnetic field component. This definition is consistent with Barr et al.

[ ] and Moore et al. [ ]. Twenty-four-hour direction-finding measurements made on 19 February at the mid-latitude stations separated km apart in latitude have shown that VLF emissions can be released from various.

The analysis of polarization eccentricity and numerical simulations discussed in the following sections provides evidence that observed ELF/VLF waves at Chistochina and Paradise are sourced predominantly from the stronger Hall dipole while the waves at Paxson.

VLF emissions study at Syowa Station, Antarctica -Polar chorus emission and worldwide geomagnetic variation - March No. N1sHINO, M. et al.: Polarization and arriving direction of VLF em1ss1ons.

July No. HIRASAWA, T. and K. KAM!NUMA: Space-time variation of aurora and geomagnetic disturbances -Auroral observations at Syowa.

KOKUBUN, S. et al.: VLF emissions study at Syowa Station, Antarctica -Polar chorus emission and worldwide geomagnetic variation. March No. NISHINO, M. and TANAKA, Y.: Polarization and arriving direction of VLF emissions.

July No. HIRASAWA, T. and KAMINUMA, K.: Space-time variation of aurora and geomagnetic disturbances. For example, Fedorenko [10] gave the influences of Earth-ionosphere waveguide on the polarization of ELF/VLF waves, Tereshchenko [11] presented the features of amplitude and Doppler frequency.

Linear polarization is not the only possibility. Another type is circular polarization. The best way to visualize this is like a corkscrew. The electric field rotates as it travels along. If the rotation is clockwise as seen looking in the direction of propagation, it is called right-hand circular polarization (RHCP).

The other possibility is LHCP. We estimated the arrival azimuth by taking the ratio of Bx/By for the emissions with anomalous amplitude during October. The estimated azimuth (mean value) is indicated in Fig.

The azimuthal direction is 55 ° from the East, which is consistent with the epicentral direction. If "vlf" means "very low frequency" radio, then the speed ismeters (, miles) per second.

Masanori Nishino has written: 'Polarization and arriving direction of VLF emissions. VLF emissions study at Syowa Station, Antarctica-Polar chorus emission and world wide geomagnetic variation.

March No NISHIO, M. and TANAKA, Y.: Polarization and arriving direction of VLF emissions. July No A new apparatus combining a tracking receiver and a direction-finding signal processor for observation of VLF whistler mode signals is described.

The system is expected to achieve greater bearing accuracy than can be obtained from a conventional goniometer and is usable on a wider variety of signals than can be processed by most other techniques.

Convenience in data output has been emphasized. polarization is thus fairly well understood, but it is necessary to wait for more than 50 yeras before the first astronomical application of polarization. In Hale succeeds in observing the spectrum of a sunspot in two opposite direction of circular polarization and, from the observed shift of the spectral lines deduces the existence.

Structured Pc 1 signals propagate in the ionospheric F2 region duct from their secondary sources at high latitudes to lower latitudes. Propagation directions to low latitude stations can be inferred from measurements of polarization parameters. The analysis of five events recorded at two low latitude stations (L = ) are presented.

Direction of arrival measurements are used to investigate. Most emissions are detected as having left-hand (L) circular (or ordinary O) polarization, but the companion paper [LaBelle and Chen, ] presents a systematic experimental study on the rare.

Yamaguchi M., Hattori K., Iwama N., Hayakawa M. () A New Direction Finding Method of Magnetospheric VLF/ELF Radio Waves Using the Linear Regularization and Generalized Cross Validation. In: Kikuchi H. (eds) Dusty and Dirty Plasmas, Noise, and. VLF signals radiated by a 1st return stroke and a cloud discharge are shown above at left.

Each waveform is shown on slow (top two examples, μs/div) and faster (bottom two signals, 20 μs/div) time scales. RF radiation consisting of isolated pulses and a burst of quasi-continuous radiation is shown above at right (adapted from the Cummins and Murphy () paper cited at the start of this.

Abstract. A new ground-based direction finding technique is proposed to estimate the ionospheric exit regions of magnetospheric VLF waves on the basis of wave energy distribution of those waves in wave number space which is evaluated by means of maximum entropy concept.

The Sun and many other light sources produce waves that are randomly polarized (see Figure 4). Such light is said to be unpolarized because it is composed of many waves with all possible directions of polarization.

Polaroid materials, invented by the founder of Polaroid Corporation, Edwin Land, act as a polarizing slit for light, allowing only polarization in one direction to pass through.

We reveal previously unknown quasi-periodic (QP) very low frequency (VLF) emissions at the unusually high-frequency band of ∼ 7–12 kHz by applying the digital filtering of strong atmospherics to the ground-based VLF data recorded at Kannuslehto station (KAN). It is located in northern Finland at L ∼ The frequencies of QP emissions are much higher than the equatorial electron.

The new result, demonstrating that the polarization of $$emissions is left-hand, implies that these, like higher frequency MFB, propagate in the LO-mode in the ionosphere, which constrains the source to locations where the MFB frequency exceeds the L-cutoff frequency (\(f_{\mathrm{L}}$$).Figure 4a is a spectrogram of the event observed at Toolik Lake, UT on.

@article{osti_, title = {The magnetoionic modes and propagation properties of auroral radio emissions}, author = {Calvert, W and Hashimoto, Kozo}, abstractNote = {The different magnetoionic wave modes which accompany the aurora are identified using DE 1 not only by their appearance on satellite radio spectrograms, but also by concurrent measurements of their wave polarization and.

The pattern recognition polarization ratio should be obtained which can differentiate emissions from seismogenic effects of geomagnetic activity. ULF emission patterns generated that seismogenic effect has duration > 5 days and the dominance of emission intensity recorded at the Z component and for the dominance of the emission intensity of.

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VLF response is a maximum when the target strikes in the direction of the transmitter, falling off roughly as the cosine of the strike angle for other directions. However, there are a number of transmitters worldwide and seldom is the selection of an appropriate transmitter a problem.Abstract.

We present LOFAR measurements of radio emission from extensive air showers. We find that this emission is strongly polarized, with a median degree of polarization of nearly 99%, and that the angle between the polarization direction of the electric field and the Lorentz force acting on the particles, depends on the observer location in the shower plane.focus on the daytime VLF emissions observed during the storm main phase after 04 UT.

The more detailed spectrograms ( kHz, the total, left-hand and right-hand polarized wave power) for UT are presented in Fig. 6. The bottom panel (Az) shows the angle direction (not the vector!) of the wave arrival.

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