Electron Precipitation at an Auroral Latitude – Saskatoon, L = 4.4. I. Photometer, Magnetometer, and Radiowave Data

1974 ◽  
Vol 52 (19) ◽  
pp. 1872-1878 ◽  
Author(s):  
Z. M. Khan ◽  
A. H. Manson
Keyword(s):  
Solar Maximum ◽  
Ionospheric Disturbance ◽  
Lower Ionosphere ◽  
Electron Precipitation ◽  
Ionospheric Disturbances ◽  
Partial Reflection ◽  
Four Seasons ◽  
General Correspondence ◽  
Auroral Latitude ◽  
Magnetic Disturbances

A study of the quiet and disturbed lower ionosphere (60–100 km) near solar maximum years (1970–1971) has been carried out at Saskatoon (52 °N, 106 °W, L = 4.4) using a variety of techniques: a 5577 Å photometer, a magnetometer, a 'partial reflection radiowave system' (2.2 MHz), and an all-sky camera. Good correspondences between local and planetary magnetic disturbances and the green line intensity I(5577 Å) have been found. Radiowave data, ordered in terms of I(5577 Å), have been used in seasonal epoch analyses for the four seasons. It is shown that after the photometric maxima near geomagnetic midnight, ionospheric disturbances below 80 km continue to increase in magnitude towards sunrise. They are evident until at least noon the following day. For a given level of I(5577 Å), the ionospheric disturbance (< 90 km) is largest during the night hours in summer and winter; and after sunrise, largest in winter and fall months. There is good general correspondence between these results, and fluxes of precipitated electrons measured by satellite techniques.

scholarly journals Co-Seismic Ionospheric Disturbance with Alaska Strike-Slip Mw7.9 Earthquake on 23 January 2018 Monitored by GPS

Atmosphere ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 83
Author(s):  
Yongming Zhang ◽  
Xin Liu ◽  
Jinyun Guo ◽  
Kunpeng Shi ◽  
Maosheng Zhou ◽  
...  
Keyword(s):  
Fault Location ◽  
Ionospheric Disturbance ◽  
Near Field ◽  
Singular Spectrum Analysis ◽  
Maximum Amplitude ◽  
Strike Slip ◽  
Ionospheric Disturbances ◽  
Total Electron ◽  
Total Electron Contents ◽  
Alaska Earthquake

The Mw7.9 Alaska earthquake at 09:31:40 UTC on 23 January 2018 occurred as the result of strike slip faulting within the shallow lithosphere of the Pacific plate. Global positioning system (GPS) data were used to calculate the slant total electron contents above the epicenter. The singular spectrum analysis (SSA) method was used to extract detailed ionospheric disturbance information, and to monitor the co-seismic ionospheric disturbances (CIDs) of the Alaska earthquake. The results show that the near-field CIDs were detected 8–12 min after the main shock, and the typical compression-rarefaction wave (N-shaped wave) appeared. The ionospheric disturbances propagate to the southwest at a horizontal velocity of 2.61 km/s within 500 km from the epicenter. The maximum amplitude of CIDs appears about 0.16 TECU (1TECU = 1016 el m−2) near the epicenter, and gradually decreases with the location of sub-ionospheric points (SIPs) far away from the epicenter. The attenuation rate of amplitude slows down as the distance between the SIPs and the epicenter increases. The direction of the CIDs caused by strike-slip faults may be affected by the horizontal direction of fault slip. The propagation characteristics of the ionospheric disturbance in the Alaska earthquake may be related to the complex conditions of focal mechanisms and fault location.

scholarly journals A study of atmospheric gravity waves and travelling ionospheric disturbances at equatorial latitudes

1997 ◽  
Vol 15 (8) ◽  
pp. 1048-1056 ◽  
Author(s):  
R. L. Balthazor ◽  
R. J. Moffett
Keyword(s):  
Gravity Waves ◽  
Large Scale ◽  
Ionospheric Disturbance ◽  
Magnetic Equator ◽  
Ionospheric Disturbances ◽  
Atmospheric Gravity Waves ◽  
Opposite Hemisphere ◽  
Travelling Ionospheric Disturbances ◽  
F Region ◽  
Atmospheric Gravity

Abstract. A global coupled thermosphere-ionosphere-plasmasphere model is used to simulate a family of large-scale imperfectly ducted atmospheric gravity waves (AGWs) and associated travelling ionospheric disturbances (TIDs) originating at conjugate magnetic latitudes in the north and south auroral zones and subsequently propagating meridionally to equatorial latitudes. A 'fast' dominant mode and two slower modes are identified. We find that, at the magnetic equator, all the clearly identified modes of AGW interfere constructively and pass through to the opposite hemisphere with unchanged velocity. At F-region altitudes the 'fast' AGW has the largest amplitude, and when northward propagating and southward propagating modes interfere at the equator, the TID (as parameterised by the fractional change in the electron density at the F2 peak) increases in magnitude at the equator. The amplitude of the TID at the magnetic equator is increased compared to mid-latitudes in both upper and lower F-regions with a larger increase in the upper F-region. The ionospheric disturbance at the equator persists in the upper F-region for about 1 hour and in the lower F-region for 2.5 hours after the AGWs first interfere, and it is suggested that this is due to enhancements of the TID by slower AGW modes arriving later at the magnetic equator. The complex effects of the interplays of the TIDs generated in the equatorial plasmasphere are analysed by examining neutral and ion winds predicted by the model, and are demonstrated to be consequences of the forcing of the plasmasphere along the magnetic field lines by the neutral air pressure wave.

Ionization increases associated with the small solar proton events of 5 February 1965 and 16 July 1966

1969 ◽  
Vol 47 (2) ◽  
pp. 131-134 ◽  
Author(s):  
L. W. Hewitt
Keyword(s):  
Lower Ionosphere ◽  
Solar Proton ◽  
Satellite Observations ◽  
Geographic Latitude ◽  
Electron Number ◽  
Partial Reflection ◽  
D Region ◽  
Resolute Bay ◽  
Solar Proton Events

Observations of partial reflections from the ionosphere at vertical incidence at 2.66 MHz have been made at Resolute Bay, geographic latitude 74.7 °N, since September 1963. By measuring the amplitudes of the ordinary and extraordinary backscattered waves information is obtained about electron number densities in the lower ionosphere. The results presented in this paper show that the partial reflection technique is more sensitive than most other ground-based experiments for the detection of D-region ionization increases associated with small solar proton events. Results obtained by the partial reflection experiment during the events of 5 February 1965 and 16 July 1966 are presented and compared with VLF and satellite observations.

scholarly journals The synthesis of travelling ionospheric disturbance (TID) signatures in HF radar observations using ray tracing

2000 ◽  
Vol 18 (1) ◽  
pp. 56-64 ◽  
Author(s):  
A. J. Stocker ◽  
N. F. Arnold ◽  
T. B. Jones
Keyword(s):  
Ray Tracing ◽  
Electron Density ◽  
Ionospheric Disturbance ◽  
Density Perturbation ◽  
Hf Radar ◽  
Ionospheric Disturbances ◽  
F Region ◽  
Abstract Characteristic ◽  
Electron Density Perturbation ◽  
Radar Frequency

Abstract. Characteristic signatures are often observed in HF radar range-time-intensity plots when travelling ionospheric disturbances (TIDs) are present. These signatures, in particular the variation of the F-region skip distance, have been synthesised using a ray tracing model. The magnitude of the skip variation is found to be a function of the peak electron density perturbation associated with the TID and radar frequency. Examination of experimental observations leads to an estimate of the peak electron density perturbation amplitude of around 25% for those TIDs observed by the CUTLASS radar system. The advantage of using the skip variation over the radar return amplitude as an indicator of density perturbation is also discussed. An example of a dual radar frequency experiment has been given. The investigation of the effect of radar frequency on the observations will aid the optimisation of future experiments..Key words. Ionosphere (auroral ionosphere; ionosphere -atmosphere interactions; ionospheric disturbances)

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.

scholarly journals Comparison of travelling ionospheric disturbance measurements with thermosphere/ionosphere model results

2003 ◽  
Vol 21 (4) ◽  
pp. 1031-1037 ◽  
Author(s):  
Ya. F. Ashkaliev ◽  
G. I. Gordienko ◽  
Ch. Jacobi ◽  
Yu. G. Litvinov ◽  
V. V. Vodyannikov ◽  
...  
Keyword(s):  
Ionospheric Disturbance ◽  
Temporal Variations ◽  
Slab Thickness ◽  
Electron Content ◽  
Ionospheric Disturbances ◽  
Ionosphere Model ◽  
Parameter Variations ◽  
Atmosphere Interaction ◽  
Atmospheric Gravity ◽  
Layer Peak

Abstract. Comparisons of modeled and measured responses of the ionosphere to the passage of atmospheric gravity waves are made for data recorded by an ionosonde located at Almaty (76°55' E, 43°15' N) from June 2000 until May 2001. Temporal variations of the altitude (hmF) and electron content (NmF) of the F-layer peak are used for comparisons. A significant part of the observations showed well-defined wave structures on the hmF, NmF and other parameter variations observed throughout the entire nights. Both the modeling study and measurements showed that, as the F-layer is lifted by the positive surge in gravity wave, the electron content at the F-layer peak decreases, with the slab thickness being increased as well. Subsequently, the opposite happens as hmF falls below its equilibrium value. Some discrepancy between the model and experimental results related to the phase difference between hmF and NmF variations is revealed.Key words. Ionosphere (ionosphere-atmosphere interaction, ionospheric disturbances)

scholarly journals Remote sensing and modeling of energetic electron precipitation into the lower ionosphere using VLF/LF radio waves and field aligned current data

2015 ◽  
Vol 13 ◽  
pp. 233-242
Author(s):  
E. D. Schmitter
Keyword(s):  
Distribution Function ◽  
Energetic Electron ◽  
Lower Ionosphere ◽  
Signal Amplitude ◽  
Reaction Rates ◽  
Current Data ◽  
Electron Precipitation ◽  
Propagation Path ◽  
Satellite Mission ◽  
Field Aligned Current

Abstract. A model for the development of electron density height profiles based on space time distributed ionization sources and reaction rates in the lower ionosphere is described. Special attention is payed to the definition of an auroral oval distribution function for energetic electron energy input into the lower ionosphere based on a Maxwellian energy spectrum. The distribution function is controlled by an activity parameter which is defined proportional to radio signal amplitude disturbances of a VLF/LF transmitter. Adjusting the proportionality constant allows to model precipitation caused VLF/LF signal disturbances using radio wave propagation calculations and to scale the distribution function. Field aligned current (FAC) data from the new Swarm satellite mission are used to constrain the spatial extent of the distribution function. As an example electron precipitation bursts during a moderate substorm on the 12 April 2014 (midnight–dawn) are modeled along the subauroral propagation path from the NFR/TFK transmitter (37.5 kHz, Iceland) to a midlatitude site.

scholarly journals The Effect of Sudden Ionospheric Disturbances (S.I.D.'s) on 2·28 Mc/s Pulse Reflections from the Lower Ionosphere

1959 ◽  
Vol 12 (1) ◽  
pp. 42 ◽  
Author(s):  
FF Gardner
Keyword(s):  
Electron Density ◽  
Lower Ionosphere ◽  
High Sensitivity ◽  
Relative Increase ◽  
Ionospheric Disturbances ◽  
Complicated Structure ◽  
Height Range ◽  
E Region

The effects of sudden ionospheric disturbances (S.LD.'s) on the complicated structure ()f ionospheric echoes obtained with moderately high sensitivity at 2�28 Mcls are described. The observations indicate that flares of classes 2 and 3 can produce high values of electron density near the base of the ionosphere. Mean electron density can exceed 1000/cm3 over the height range 60-75 km, where the greatest relative increase in ionization occurs. Nevertheless, the greater part of the S.LD. absorption of waves reflected from the E region or above still occurs above 85 km.

scholarly journals Ionospheric disturbances over East Asia during intense December magnetic storms of 2006 and 2015: similarities and differences

2018 ◽  
Vol 4 (3) ◽  
pp. 28-42 ◽  
Author(s):  
Нина Золотухина ◽  
Nina Zolotukhina ◽  
Владимир Куркин ◽  
Vladimir Kurkin ◽  
Неля Полех ◽  
...  
Keyword(s):  
East Asia ◽  
Critical Frequency ◽  
Geomagnetic Storms ◽  
Initial Conditions ◽  
Ionospheric Disturbance ◽  
Magnetic Storms ◽  
Electron Content ◽  
Ionospheric Disturbances ◽  
Early Recovery ◽  
Total Electron

Using data from ionosondes, located in East Asia, and total electron content maps, we have made a comparative analysis of ionospheric disturbances associated with the intense geomagnetic storms of December 14–16, 2006 and December 19–22, 2015. These storms had almost equal peak intensities (Dstmin=–162 and –155 nT), but different durations of the main phases (2.5 and 19 hr). At the beginning of both the storms, the region under study was located in the vicinity of the midnight meridian. Ionospheric responses to magnetic storms differed in: i) an increase in the F2-layer critical frequency at subauroral latitudes, caused by an increase in auroral precipitation, during the initial phase of the former storm and the absence of this effect in the latter; (ii) a sharp drop in the critical frequency in the evening hours of the main phase of the latter storm, caused by a shift of the main ionospheric trough to lower latitudes, and the absence of this effect during the former storm; (iii) generation of a short-term positive disturbance observed at subauroral latitudes only in the early recovery phase of the former storm after the negative ionospheric disturbance. During both the storms at middle latitudes there were positive disturbances and wave-like fluctuations of the critical frequency which increased in the vicinity of the dawn meridian. The main causes of the differences between the ionospheric storms are shown to be the differences between the initial conditions of the magnetosphere–ionosphere system and durations of the main phases of magnetic storms.

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