Solar flare (S.I.D.) effects on the propagation of 164 Kc./s. radio-waves from Tashkent to Ahmedabad

1963 ◽  
Vol 57 (2) ◽  
pp. 49-68 ◽  
Author(s):  
J. S. Shirke ◽  
S. K. Alurkar
Keyword(s):  
Solar Flare ◽  
Radio Waves

Studying the ionospheric absorption during large solar flare events in September 2017

2020 ◽  
Author(s):  
Attila Buzas ◽  
Veronika Barta ◽  
Daniel Kouba
Keyword(s):  
Solar Flare ◽  
Solar Flares ◽  
Radio Waves ◽  
Absorption Data ◽  
Ionospheric Response ◽  
Enhanced Absorption ◽  
Radio Wave Absorption ◽  
Cycle 24 ◽  
Low Latitude Ionosphere ◽  
University Of Massachusetts

<p>The most intense external force affecting the ionosphere from above is related to large solar flare events, therefore it is of particular importance to study their impact on the ionosphere. During solar flares, the suddenly increased radiation causes increased ionization and enhanced absorption of radio waves leading to partial or even total radio fade-out lasting for hours in some cases (e. g. [1] [2]).</p><p> </p><p>The ionospheric response to large solar flares have been investigated using the ionosonde data measured at Pruhonice (PQ052, 50°, 14.5°) in September 2017, the most active solar period of Solar Cycle 24. A novel method [3] to calculate and investigate the absorption of radio waves propagating in the ionosphere is used to determine the absorption during large solar flare events (M and X class). Subsequently, the absorption data are compared with the indicators derived from the f<sub>min</sub> method (f<sub>min</sub>, the minimum frequency is considered as a qualitative proxy for the “nondeviative” radio wave absorption occurring in the D-layer). Total and partial radio fade-out and increased values (with 2-5 MHz) of the f<sub>min</sub> parameter were experienced during and after the intense solar flares (> M3). The combination of these two methods may prove to be an efficient approach to monitor the ionospheric response to solar flares.</p><p> </p><p>[1] Sripathi, S., Balachandran, N., Veenadhari, B., Singh, R., and Emperumal, K.: Response of the equatorial and low-latitude ionosphere to an intense X-class solar flare (X7/2B) as observed on 09 August 2011, J. Geophys. Res.-Space, 118, 2648–2659, 2013.</p><p>[2] Barta, V., Sátori, G., Berényi, K. A., Kis, Á., and Williams, E. (2019). Effects of solar flares on the ionosphere as shown by the dynamics of ionograms recorded in Europe and South Africa. Annales Geophysicae, Vol. 37, No. 4, pp. 747-761</p><p>[3] Sales, G. S., 2009, HF absorption measurements using routine digisonde data, Conference material, XII. International Digisonde Forum, University of Massachusetts</p>

scholarly journals Geomagnetic Pulsations, Blackout and Low-Latitude Aurorae Associated with Power Magnetic Storm

2021 ◽  
Vol 3 (4) ◽  
pp. 279-289
Author(s):  
Vladimir Parkhomov ◽  
Aleksandr Mikhalev ◽  
Konstantin Ratovskyi
Keyword(s):  
Solar Flare ◽  
Magnetic Storm ◽  
Geomagnetic Pulsation ◽  
Spectral Lines ◽  
Geomagnetic Pulsations ◽  
Radio Waves ◽  
Frequency Range ◽  
Low Latitude ◽  
Ionospheric Absorption ◽  
Solar Filament

The research analyzed the regularities of the dynamics of geomagnetic pulsation regimes in the frequency range 0.002–5 Hz, the generation of which reflects the interaction with the Earth's magnetosphere of the solar filament ejected by a powerful solar flare of 3B. We compared the dynamics of the change in the types and modes of geomagnetic pulsations with the dynamics of the atmosphere glow in two spectral lines and the total ionospheric absorption of radio waves. The study developed a possible model of the observed phenomenon.

Effects of X2-class solar flare events on ionospheric GPS-TEC and radio waves over Brazilian sector

2019 ◽  
Vol 63 (11) ◽  
pp. 3586-3605 ◽  
Author(s):  
A.J. de Abreu ◽  
M. Roberto ◽  
M.A. Alves ◽  
J.R. Abalde ◽  
P.A.B. Nogueira ◽  
...  
Keyword(s):  
Solar Flare ◽  
Radio Waves ◽  
Gps Tec

scholarly journals Statistical analysis of short-wave fadeout for extreme space weather event estimation

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Chihiro Tao ◽  
Michi Nishioka ◽  
Susumu Saito ◽  
Daikou Shiota ◽  
Kyoko Watanabe ◽  
...  
Keyword(s):  
Solar Flare ◽  
Zenith Angle ◽  
Solar Zenith Angle ◽  
Empirical Relationship ◽  
Short Wave ◽  
Information And Communications Technology ◽  
Radio Waves ◽  
Long Distance ◽  
Noise Absorption ◽  
Cosmic Noise

AbstractSolar flares trigger an increase in plasma density in the ionosphere including the D region, and cause the absorption of radio waves, especially in high-frequency (HF) ranges, called short-wave fadeout (SWF). To evaluate the SWF duration and absorption statistically, we analyze long-term (36 years) ionosonde data observed by the National Institute of Information and Communications Technology (NICT). The minimum reflection frequency, fmin, is used to detect SWFs from 15-min-resolution ionosonde observations at Kokubunji, Tokyo, from 1981 to 2016. Since fmin varies with local time (LT) and season, we refer to dfmin, which is defined as fmin subtracted by its 27-day running median at the same LT. We find that the occurrence of SWFs detected by three criteria, (i) dfmin ≥ 2.5 MHz, (ii) dfmin ≥ 3.5 MHz, and (iii) blackout, during daytime associated with any flare(s) greater than the C1 class is maximized at local noon and decreases with increasing solar zenith angle. We confirm that the dfmin and duration of SWFs increase with the solar flare class. We estimate the absorption intensity from observations, which is comparable to an empirical relationship obtained from sudden cosmic noise absorption. A generalized empirical relationship for absorption from long-distance circuits shows quantitatively different dependences on solar flare flux, solar zenith angle, and frequency caused by different signal passes compared with that obtained from cosmic noise absorption. From our analysis and the empirical relationships, we estimate the duration of extreme events with occurrence probabilities of once per 10, 100, and 1000 years to be 1.8–3.6, 4.0–6.8, and 7.4–11.9 h, respectively. The longest duration of SWFs of about 12 h is comparable to the solar flare duration derived from an empirical relationship between the solar flare duration and the solar active area for the largest solar active region observed so far.

scholarly journals PRELIMINARY RESULT OF VLF RECEIVER INSTALLATION FOR SPACE WEATHER RESEARCH

2019 ◽  
Author(s):  
Dyah Rahayu Martiningrum
Keyword(s):  
Solar Flare ◽  
Space Weather ◽  
Ionospheric Disturbances ◽  
The Sun ◽  
Radio Waves ◽  
Data Logger ◽  
Science Center ◽  
Radio Signals ◽  
Research Plan ◽  
Indirect Indication

About 40 km altitude, VLF radio waves are partially reflected and partially absorbed by the D-layer of the ionosphere. By measuring the amplitude of radio signals after they have reflected from the ionosphere, it is possible to detect kinds of ionospheric and space activity taking place. Recently, Division Ionosphere and Telecommunication, Space Science Center, National Institute of Aeronautics and Space (LAPAN) have installed VLF receiver to investigate effects of solar flare to ionosphere, mainly Sudden Ionospheric Disturbances (SIDs). By monitoring transmission from Earth-based beacons which are affected by variabilities in the ionosphere, giving an indirect indication of events on the Sun. The VLF receiver output is a voltage varying with time, which may be fed to any data logger or digital multimeter. In this paper, we discuss about system of UKRAA (United Kingdom Radio Astronomy Association) VLF receiver, our research plan related to this instrument, and preliminary result of installation of VLF receiver

Solar Flare Energetic Neutral Emission Measurements in the Project Coronas-I

1994 ◽  
Vol 144 ◽  
pp. 635-639
Author(s):  
J. Baláž ◽  
A. V. Dmitriev ◽  
M. A. Kovalevskaya ◽  
K. Kudela ◽  
S. N. Kuznetsov ◽  
...  
Keyword(s):  
Solar Flare ◽  
Energy Range ◽  
Gamma Rays ◽  
Pulse Shape ◽  
Gamma Ray ◽  
Pulse Shape Discrimination ◽  
Shape Discrimination ◽  
Solar Neutron ◽  
Low Altitude

AbstractThe experiment SONG (SOlar Neutron and Gamma rays) for the low altitude satellite CORONAS-I is described. The instrument is capable to provide gamma-ray line and continuum detection in the energy range 0.1 – 100 MeV as well as detection of neutrons with energies above 30 MeV. As a by-product, the electrons in the range 11 – 108 MeV will be measured too. The pulse shape discrimination technique (PSD) is used.

Radio Measurements of Coronal Magnetic Fields

1994 ◽  
Vol 144 ◽  
pp. 21-28 ◽  
Author(s):  
G. B. Gelfreikh
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Active Regions ◽  
High Sensitivity ◽  
Coronal Magnetic Field ◽  
Transverse Magnetic ◽  
Radio Sources ◽  
Radio Waves ◽  
Solar Active Regions

AbstractA review of methods of measuring magnetic fields in the solar corona using spectral-polarization observations at microwaves with high spatial resolution is presented. The methods are based on the theory of thermal bremsstrahlung, thermal cyclotron emission, propagation of radio waves in quasi-transverse magnetic field and Faraday rotation of the plane of polarization. The most explicit program of measurements of magnetic fields in the atmosphere of solar active regions has been carried out using radio observations performed on the large reflector radio telescope of the Russian Academy of Sciences — RATAN-600. This proved possible due to good wavelength coverage, multichannel spectrographs observations and high sensitivity to polarization of the instrument. Besides direct measurements of the strength of the magnetic fields in some cases the peculiar parameters of radio sources, such as very steep spectra and high brightness temperatures provide some information on a very complicated local structure of the coronal magnetic field. Of special interest are the results found from combined RATAN-600 and large antennas of aperture synthesis (VLA and WSRT), the latter giving more detailed information on twodimensional structure of radio sources. The bulk of the data obtained allows us to investigate themagnetospheresof the solar active regions as the space in the solar corona where the structures and physical processes are controlled both by the photospheric/underphotospheric currents and surrounding “quiet” corona.

Radio Waves Kill Insect Pests

1933 ◽  
Vol 148 (5) ◽  
pp. 272-273 ◽  
Author(s):  
J. H. Davis
Keyword(s):  
Insect Pests ◽  
Radio Waves
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