scholarly journals A Study of "Spread?F" Ionospheric Echoes at Night at Brisbane. I. Range Spreading (Experimental)

1956 ◽  
Vol 9 (2) ◽  
pp. 247 ◽  
Author(s):  
RWE McNicol ◽  
HC Webster ◽  
GG Bowman
Keyword(s):  
Critical Frequency ◽  
Fixed Frequency ◽  
Night Time ◽  
Range Measurements ◽  
Phase Path ◽  
Spread F

At frequencies well below the critical frequency, satellite echoes sometimes accompany the night-time F2 echo, sometimes clearly separated, sometimes overlapping. In an investigation of these range multiplets, in addition to routine P'f sounding records, continuous virtual range measurements at fixed frequency (at stations of various separations), and measurements of mean intensities, phase-path changes, and directions of arrival, have been carried out.

scholarly journals Synchronization of geomagnetic and ionospheric disturbances over Kazan station

2017 ◽  
Vol 3 (4) ◽  
pp. 63-73
Author(s):  
Оксана Бархатова ◽  
Oksana Barhatova ◽  
Наталья Косолапова ◽  
Natal'ya Kosolapova ◽  
Николай Бархатов ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Geomagnetic Field ◽  
Critical Frequency ◽  
Ionospheric Disturbances ◽  
Spectral Features ◽  
Quiet Period ◽  
Geomagnetic Disturbances ◽  
Night Time ◽  
Dynamic Spectra ◽  
Solar Wind Parameters

We have analyzed the phenomena which accompany synchronization of night-time ionospheric and geomagnetic disturbances in an ULF range with periods 35–50 min near the mid-latitude station Kazan during a global magnetically quiet period. The comparison between dynamic spectra and wavelet patterns of these disturbances has revealed that spectral features of simultaneous disturbances of the F2-layer critical frequency and H, D, Z geomagnetic field components are similar. By studying spectral features of the F2-layer critical frequency over Kazan and disturbances of the H and D geomagnetic field components at magnetic stations which differ from Kazan in longitude and latitude, we have established that the disturbances considered belong to the class of fast magnetosonic waves. The analysis of solar wind parameters, interplanetary magnetic field (IMF), and values of the auroral index AL in the period under study has shown that this event is associated with IMF Bz component disturbances and occurs during substorm development.

scholarly journals Spread-F characteristics at the southern anomaly crest in South America during the descending phase of solar cycle 24

2021 ◽  
Author(s):  
Gilda de Lourdes González
Keyword(s):  
Solar Activity ◽  
South America ◽  
Communication Systems ◽  
Temporal Distribution ◽  
Plasma Bubble ◽  
Night Time ◽  
Plasma Bubbles ◽  
Wide Range ◽  
Spread F ◽  
Range Spread

Abstract Ionospheric F-region irregularities can acutely affect navigation and communication systems. To develop predictive capabilities on their occurrence, it is key to understand their variabilities in a wide range of time scales. Previous studies at low latitudes in South America have been performed mostly for the eastern sector, and fewer efforts have been done in the Argentinian region. This work presents the analysis of the spread-F (range spread-F, frequency spread-F and strong spread-F) and plasma bubble occurrence characteristics near the southern crest of the Equatorial Ionization Anomaly (Tucumán, 26.8°S, 65.2°W; magnetic latitude 15.5°S). We used ionosonde and Global Positioning System (GPS) data from November 2014 to December 2019 for different solar and geomagnetic conditions. The data shows that spread-F and plasma bubble occurrence rates peak in summer and are minimum in equinox and winter, respectively. There is, usually, a negative correlation between each type of spread-F and solar activity, whereas the opposite happens for plasma bubbles. Geomagnetic activity suppresses the generation of spread-F in equinox and summer and enhances it in winter. Plasma bubble occurrence is higher during disturbed days than during quiet days, but under medium solar activity, summer months register more plasma bubbles in quiet conditions. Range spread-F observed in winter under low solar activity is not associated with plasma bubbles originated at the magnetic equator. These results contribute to the knowledge necessary to improve the prediction of the spatial and temporal distribution of the night-time ionospheric irregularities.

scholarly journals Variations of ionospheric and geomagnetic field parameters during the June 18, 2013 Bachat earthquake

2021 ◽  
Vol 7 (1) ◽  
pp. 98-105
Author(s):  
Anastasiya Belinskaya ◽  
Aleksandr Kovalev ◽  
Nikolay Semakov ◽  
Sofiya Belinskaya
Keyword(s):  
Magnetic Moment ◽  
Sharp Increase ◽  
Critical Frequency ◽  
Sharp Decrease ◽  
Night Time ◽  
The Third ◽  
Subsequent Period ◽  
Time Region ◽  
Magnetic Constant ◽  
Precursors Of Earthquakes

The paper presents the results of a study of variations in ionospheric parameters and local magnetic constant before, during, and after the Вachat earthquake, which occurred on June 18, 2013 at 23:02 UT (June 19, 2013 at 06:02 LT) with a magnitude 5.3–5.6 and epicenter coordinates 54.29° N, 86.17° E. We have used data from IPGG SB RAS and TSU ionospheric stations and INTERMAGNET geomagnetic observatories. We have established that in the period preceding the earthquake there was a rather sharp increase in the magnetic moment, and in the subsequent period there was an equally sharp decrease in the magnetic moment. It is noted that the analysis of the daily average values of the local magnetic constant is the most promising for searching for geomagnetic precursors of earthquakes. We have found a low strong sporadic layer Es for two days before the event, the like of which was not observed for 15 days before and 15 days after the event. In addition, on the days preceding the shock, the background values of the F2-layer critical frequency were larger by more than 20 % at the local pre-event hours. On the second day after the earthquake, there appeared a night-time region of low values (about 14 %), which persisted until the morning of the third day.

scholarly journals Variations of ionospheric and geomagnetic field parameters during the June 18, 2013 Bachat earthquake

2021 ◽  
Vol 7 (1) ◽  
pp. 78-84
Author(s):  
Anastasiya Belinskaya ◽  
Aleksandr Kovalev ◽  
Nikolay Semakov ◽  
Sofiya Belinskaya
Keyword(s):  
Magnetic Moment ◽  
Sharp Increase ◽  
Critical Frequency ◽  
Sharp Decrease ◽  
Night Time ◽  
The Third ◽  
Subsequent Period ◽  
Time Region ◽  
Magnetic Constant ◽  
Precursors Of Earthquakes

The paper presents the results of a study of variations in ionospheric parameters and local magnetic constant before, during, and after the Vachat earthquake, which occurred on June 18, 2013 at 23:02 UT (June 19, 2013 at 06:02 LT) with a magnitude 5.3–5.6 and epicenter coordinates 54.29 ° N, 86.17 ° E. We have used data from IPGG SB RAS and TSU ionospheric stations and INTERMAGNET geomagnetic observatories. We have established that in the period preceding the earthquake there was a rather sharp increase in the magnetic moment, and in the subsequent period there was an equally sharp decrease in the magnetic moment. It is noted that the analysis of the daily average values ​​of the local magnetic constant is the most promising for searching for geomagnetic precursors of earthquakes. We have found a low strong sporadic layer Es for two days before the event, the like of which was not observed for 15 days before and 15 days after the event. In addition, on the days preceding the shock, the background values ​​of the F2-layer critical frequency were larger by more than 20% at the local pre-event hours. On the second day after the earthquake, there appeared a night-time region of low values ​​(about 14%), which persisted until the morning of the third day.

High Multiple Radio Reflections from the F2 Layer of the Ionosphere at Brisbane

1954 ◽  
Vol 7 (1) ◽  
pp. 165 ◽  
Author(s):  
K Baird
Keyword(s):  
Normal Incidence ◽  
Reflection Coefficients ◽  
Fixed Frequency ◽  
Night Time ◽  
Variable Gain

Continuous night-time records of multiple F2 reflections at normal incidence have been made at a fixed frequency. The echo patterns have been classified, and qualitative explanations given in terms of humped ionization contours, extending the work of Pierce and Mimno (1940). These patterns have been studied also by a variable gain technique. It is concluded that accurate measurements of reflection coefficients cannot be made by this means.

scholarly journals Analysis of the efficiency of earthquake prediction based on the anomalous behavior of ionospheric parameters on the eve of earthquakes in the Kamchatka region

2018 ◽  
Vol 62 ◽  
pp. 03001 ◽  
Author(s):  
Vadim Bogdanov ◽  
Aleksey Pavlov
Keyword(s):  
Critical Frequency ◽  
Anomalous Behavior ◽  
Seismic Events ◽  
Ionospheric Disturbances ◽  
Short Term ◽  
Strong Earthquakes ◽  
Perturbed State ◽  
Kamchatka Region ◽  
Spread F ◽  
Short Term Prediction

A method is presented for short-term prediction of strong earthquakes, in which the precursors are considered the excess of current values of foF2 critical frequency of the ionospheric F2 layer over the median values in periods of perturbed state of the magnetosphere, the appearance of ionospheric disturbances: K-layer, Es-spread F-spread, the stratification of the F2 layer, Es is the r type. As predicted earthquakes were considered earthquakes with magnitudes M ≥ 5:0. Assessment of the effectiveness of the forecast was carried out in the spring and autumn periods for 2013–2017 according to the methods of A. A. Gusev and G. M. Molchan. It is shown that the method under consideration has the best prognostic efficiency for seismic events with M ≥ 6:5 magnitude.

scholarly journals Spread-F characteristics over Tucumán near the southern anomaly crest in South America during the descending phase of solar cycle 24

2021 ◽  
Author(s):  
Gilda de Lourdes González
Keyword(s):  
Solar Activity ◽  
South America ◽  
Communication Systems ◽  
Eastern Region ◽  
Plasma Bubble ◽  
Night Time ◽  
Plasma Bubbles ◽  
Wide Range ◽  
Spread F ◽  
Range Spread

Abstract Ionospheric F-region irregularities can acutely affect navigation and communication systems. To develop predictive capabilities on their occurrence, it is key to understand their variabilities in a wide range of time scales. Previous studies at low latitudes in South America have been performed mostly in the eastern region. However, there are still few reports on the spread-F over Argentina owing to a lack of ionosonde data. This work presents the analysis of the spread-F (range spread-F and frequency spread-F) and plasma bubble occurrence characteristics near the southern crest of the Equatorial Ionization Anomaly in Argentina (Tucumán, 26.8°S, 65.2°W; magnetic latitude 15.5°S). We used ionosonde and Global Positioning System (GPS) data from November 2014 to December 2019 for different solar and geomagnetic conditions. The data show that spread-F and plasma bubble occurrence rates peak in local summer and are minimum in equinox and winter, respectively. There is a negative correlation between each type of spread-F and solar activity, whereas the opposite happens for plasma bubbles. Geomagnetic activity suppresses the generation of spread-F in equinox and summer and enhances it in winter. Plasma bubble occurrence is higher during disturbed days than during quiet days, but under medium solar activity, summer months register more plasma bubbles in quiet conditions. Range spread-F observed in winter under low solar activity is not associated with plasma bubbles originated at the magnetic equator. These results contribute to the knowledge necessary to improve the prediction of the spatial and temporal distribution of the night-time ionospheric irregularities.

scholarly journals Preliminary Results of Observations of Aspect-sensitive Reflections from Irregularities in the F Region

1964 ◽  
Vol 17 (4) ◽  
pp. 490 ◽  
Author(s):  
Evelyn M Swenson
Keyword(s):  
Geomagnetic Latitude ◽  
Night Time ◽  
Preliminary Results ◽  
Definite Relationship ◽  
F Region ◽  
Specular Reflections ◽  
Surface Configuration ◽  
Sensitivity Range ◽  
Spread F

Night-time radio reflections from irregularities in the F. region of the ionosphere have been studied at Brisbane (geomagnetic latitude - 35.8�), at a fr-equency of 16 Mc/s. The spatial limits and behaviour of the echoes were consistent with the hypothesis of specular reflections from field-aligned columns of ionization, with observational limitations imposed by echo surface configuration, aerial sensitivity, range attenuation, and absorption. The echoes, recorded with range-azimuth display, were of many shapes, but only a U-shape tended to recur. These U-echoes were preferentially observed under conditions of magnetic disturbace. Irregularity occurrence possibly increased with latitude from 45� to55� geomagnetic latitude. No definite relationship was found between the echoesand v.l.f. noise, radio-star scintillations, spread-F, or auroras.

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