scholarly journals X-Ray Solar Flares Observed and Detected by The New Very-Low-Frequency Receiver in Nasiriyah City, South of Iraq

2021 ◽  
Vol 32 (2) ◽  
pp. 58
Author(s):  
Habeeb Allawi ◽  
Moataz Jasim ◽  
Kareem Abdulameer Difar
Keyword(s):  
Solar Flares ◽  
Ionospheric Disturbance ◽  
Low Frequency ◽  
Ionospheric Disturbances ◽  
Very Low Frequency ◽  
Radio Signals ◽  
South Of Iraq ◽  
Set Up ◽  
June July ◽  
To Receive

A receiver station was installed at Nasiriyah (Dhi Qar University - Faculty of Sciences) to receive very low frequency (VLF) radio signals from transmitters around the world. VLF waves are excellent probes of the sudden ionospheric disturbance (SID); they detect varying properties of the D layer presented as a lower region of the ionosphere when these waves propagate through the Earth-Ionosphere Waveguide. This study describes the set-up of our station system and it demonstrates its ability to detect sudden ionospheric disturbances caused by solar flares in May, June, July, August, and September 2017. We found out that the monitoring station is working successfully to receive FLV signals, and to detect sudden ionospheric disturbances. We detected 17 events resulting from solar flare C-class, 8 events from M-class, and 3 events from X-class that caused an increase in the received FLV amplitude.

scholarly journals Investigation of the Sudden Solar Ionospheric Disturbance using Radio Telescope

2020 ◽  
Vol 240 ◽  
pp. 07003
Author(s):  
Adam Aqasha ◽  
Andrien Zheng ◽  
Sneha Athreya ◽  
Hoe Teck Tan
Keyword(s):  
Solar Flares ◽  
Solar Minimum ◽  
Solar Maximum ◽  
Ionospheric Disturbance ◽  
Low Frequency ◽  
The Sun ◽  
Radio Telescopes ◽  
Very Low Frequency ◽  
Set Up ◽  
Vlf Waves

Low-frequency radio telescopes are cheap and useful devices for the investigation of terrestrial and extra-terrestrial emissions. These emissions come either from the Sun and the planet Jupiter to terrestrial emissions. This project aims to investigate the Very Low Frequency (VLF) waves from mid-August to October 2019 using Radio JOVE (20 MHz) and SSID (3-30 kHz) to observe for the occurrence of solar flares and see how if the radio telescopes that the team set up is reliable. This will allow us future students aspiring to learn about astronomy to examine solar flares in detail during the upcoming solar maximum. Not many flares were detected as this period happens to be a solar minimum. However, a series of flares occurred between 30 September 2019 and 1 October 2019, which the telescopes have been able to detect, particularly SSID.

Observation and Analysis of Solar Flares that Cause Large-area Short-wave Communication Interruption

2021 ◽  
Author(s):  
Zhou Kangpo ◽  
Niu youtian ◽  
Liu weina ◽  
Wang zhaodi ◽  
Guo songhao ◽  
...  
Keyword(s):  
Solar Flares ◽  
Ionospheric Disturbance ◽  
Low Frequency ◽  
High Energy ◽  
Short Wave ◽  
Absorption Capacity ◽  
X Rays ◽  
Large Area ◽  
Radio Signals ◽  
Shortwave Communication

Abstract When a solar flare erupts, the sun emits a flood of X-rays and high-energy particles that reach Earth at the speed of light, causing a sudden ionospheric disturbance event (SID event). The D layer of the ionosphere absorbs high-frequency radio signals. With the increase of flare intensity, the D layer's absorption capacity becomes stronger, which leads to the decline of shortwave communication quality and even the interruption of shortwave communication. In this paper, solar flares, which caused large area short-wave communication interruption in recent years, are observed and analyzed by very low frequency (VLF) method, and the influence of solar flares on short-wave communication is summarized. Finally, several methods to deal with the short-wave communication interruption caused by solar flares are proposed.

scholarly journals Development of a Radio Telescope for Very Low Frequency Observations

2020 ◽  
Vol 240 ◽  
pp. 07004
Author(s):  
Arpit Gupta ◽  
Seow Kit Hint ◽  
Cao Shangyu ◽  
Hoe Teck Tan
Keyword(s):  
Data Collection ◽  
Solar Flare ◽  
Radio Telescope ◽  
Background Noise ◽  
Ionospheric Disturbance ◽  
Low Frequency ◽  
Ionospheric Disturbances ◽  
X Ray ◽  
Very Low Frequency ◽  
Solar Storm

Sudden ionospheric disturbances are transient changes in the ionosphere caused by enhancement in X-ray and EUV fluxes during solar flare events. The Solar Storm Radio Telescope is developed to detect Very Low Frequency (VLF) signals with frequency between 3-30 kHz transmitted from various VLF stations around the Globe. We will also be investigating different methods to reduce the background noise in the data collection. This will help to ensure an accurate hit when there is a sudden ionospheric disturbance.

Detection of Sudden Ionospheric Disturbances due to Solar flares by monitoring the Very Low Frequency signal at Malda

2010 ◽  
Author(s):  
Nilmadhab Nandy ◽  
Achintya K. Chatterjee ◽  
Md. Washimul Bari ◽  
Asit K. Choudhury ◽  
Sandip K. Chakrabarti
Keyword(s):  
Solar Flares ◽  
Low Frequency ◽  
Ionospheric Disturbances ◽  
Frequency Signal ◽  
Very Low Frequency

scholarly journals Low Ionosphere under Influence of Strong Solar Radiation: Diagnostics and Modeling

2021 ◽  
Vol 11 (16) ◽  
pp. 7194
Author(s):  
Vladimir A. Srećković ◽  
Desanka M. Šulić ◽  
Ljubinko Ignjatović ◽  
Veljko Vujčić
Keyword(s):  
Solar Radiation ◽  
Solar Flares ◽  
Low Frequency ◽  
Ionospheric Disturbances ◽  
D Region ◽  
Radio Signals ◽  
The Impact ◽  
First Time ◽  
Region Plasma ◽  
Intense Radiation

Solar flares (SFs) and intense radiation can generate additional ionization in the Earth’s atmosphere and affect its structure. These types of solar radiation and activity create sudden ionospheric disturbances (SIDs), affect electronic equipment on the ground along with signals from space, and potentially induce various natural disasters. Focus of this work is on the study of SIDs induced by X-ray SFs using very low frequency (VLF) radio signals in order to predict the impact of SFs on Earth and analyze ionosphere plasmas and its parameters. All data are recorded by VLF BEL stations and the model computation is used to obtain the daytime atmosphere parameters induced by this extreme radiation. The obtained ionospheric parameters are compared with results of other authors. For the first time we analyzed physics of the D-region—during consecutive huge SFs which continuously perturbed this layer for a few hours—in detail. We have developed an empirical model of the D-region plasma density and gave a simple approximative formula for electron density.

scholarly journals A comparative study of measured amplitude and phase perturbations of VLF and LF radio signals induced by solar flares

2014 ◽  
pp. 45-54 ◽  
Author(s):  
D.M. Sulic ◽  
V.A. Sreckovic
Keyword(s):  
Solar Flares ◽  
Low Frequency ◽  
Geographic Location ◽  
Electron Density Profile ◽  
Great Circle ◽  
Direct Result ◽  
Ionospheric Disturbances ◽  
X Ray ◽  
Radio Signals ◽  
Middle Europe

Very Low Frequency (VLF) and Low Frequency (LF) signal perturbations were examined to study ionospheric disturbances induced by solar X-ray flares in order to understand processes involved in propagation of VLF/LF radio signals over short paths and to estimate specific characteristics of each short path. The receiver at the Belgrade station is constantly monitoring the amplitude and phase of a coherent and subionospherically propagating LF signal operated in Sicily NSC at 45.90 kHz, and a VLF signal operated in Isola di Tavolara ICV at 20.27 kHz, with the great circle distances of 953 km and 976 km, respectively. A significant number of similarities between these short paths is a direct result of both transmitters and the receiver?s geographic location. The main difference is in transmitter frequencies. From July 2008 to February 2014 there were about 200 events that were chosen for further examination. All selected examples showed that the amplitude and phase of VLF and LF signals were perturbed by solar X-ray flares occurrence. This six-year period covers both minimum and maximum of solar activity. Simultaneous measurement of amplitude and phase of the VLF/LF signals during a solar flare occurrence was applied to evaluate the electron density profile versus altitude, to carry out the function of time over the middle Europe.

scholarly journals Characterization of gravity waves in the lower ionosphere using very low frequency observations at Comandante Ferraz Brazilian Antarctic Station

2020 ◽  
Vol 38 (2) ◽  
pp. 385-394
Author(s):  
Emilia Correia ◽  
Luis Tiago Medeiros Raunheitte ◽  
José Valentin Bageston ◽  
Dino Enrico D'Amico
Keyword(s):  
Low Frequency ◽  
Lower Ionosphere ◽  
Drake Passage ◽  
Wave Period ◽  
Very Low Frequency ◽  
Reflection Height ◽  
D Region ◽  
Radio Signals ◽  
Sky Conditions ◽  
The Waves

Abstract. The goal of this work is to investigate the gravity wave (GW) characteristics in the low ionosphere using very low frequency (VLF) radio signals. The spatial modulations produced by the GWs affect the conditions of the electron density at reflection height of the VLF signals, which produce fluctuations of the electrical conductivity in the D region that can be detected as variations in the amplitude and phase of VLF narrowband signals. The analysis considered the VLF signal transmitted from the US Cutler, Maine (NAA) station that was received at Comandante Ferraz Brazilian Antarctic Station (EACF, 62.1∘ S, 58.4∘ W), with its great circle path crossing the Drake Passage longitudinally. The wave periods of the GWs detected in the low ionosphere are obtained using the wavelet analysis applied to the VLF amplitude. Here the VLF technique was used as a new aspect for monitoring GW activity. It was validated comparing the wave period and duration properties of one GW event observed simultaneously with a co-located airglow all-sky imager both operating at EACF. The statistical analysis of the seasonal variation of the wave periods detected using VLF technique for 2007 showed that the GW events occurred all observed days, with the waves with a period between 5 and 10 min dominating during night hours from May to September, while during daytime hours the waves with a period between 0 and 5 min are predominant the whole year and dominate all days from November to April. These results show that VLF technique is a powerful tool to obtain the wave period and duration of GW events in the low ionosphere, with the advantage of being independent of sky conditions, and it can be used during the whole day and year-round.

scholarly journals Suppression of very low frequency radio noise in transient electromagnetic data with semi-tapered gates

2021 ◽  
Vol 10 (1) ◽  
pp. 81-90
Author(s):  
Jakob Juul Larsen ◽  
Stine Søgaard Pedersen ◽  
Nikolaj Foged ◽  
Esben Auken
Keyword(s):  
Standard Error ◽  
Signal To Noise Ratio ◽  
Low Frequency ◽  
Side Lobe ◽  
Late Time ◽  
Very Low Frequency ◽  
Transient Electromagnetic ◽  
Noise Rejection ◽  
Radio Signals ◽  
Subsurface Resistivity

Abstract. The transient electromagnetic method (TEM) is widely used for mapping subsurface resistivity structures, but data are inevitably contaminated by noise from various sources. It is common practice to gate signals from TEM systems to reduce the amount of data and improve the signal-to-noise ratio (SNR). Gating acts as a filter, and optimum gating will pass the TEM signal un-attenuated while suppressing noise. In systems based on analog boxcar integrators, the gating corresponds to filtering with a square window. The frequency response of this window shape has large side lobes, which are often insufficient in attenuating noise, e.g., from radio signals in the very low frequency (VLF) 3–30 kHz band. Tapered gates have better side lobe suppression and attenuate noise better, but tapering with analog boxcar integrators is difficult. We propose using many short boxcar gates, denoted sub-gates, and combine the sub-gates into semi-tapered gates to improve noise rejection at late gates where low signal normally leads to poor SNR. The semi-tapering approach is analyzed and tested experimentally on data from a roving TEM system. We quantify the effect of semi-tapered gates by computing an improvement factor as the ratio between the standard error of data measured with boxcar gates and the standard error of data measured with semi-tapered gates. Data from a test survey in Gedved, Denmark, with 1825 measurements gave mean improvement factors between 1.04 and 2.22 for the 10 late-time gates centered between 78.7 and 978.1 µs. After inversion of the data, we find that semi-tapering increases the depth of investigation by about 20 % for this specific survey. We conclude that the semi-tapered approach is a viable path towards increasing SNR in TEM systems based on analog boxcar integrators.

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