scholarly journals Numerical synthesis of ionograms in horizontally inhomogeneous ionosphere on the basis of compound parabolic layer model

2016 ◽  
Vol 2 (3) ◽  
pp. 52-58 ◽  
Author(s):  
Олег Ларюнин ◽  
Oleg Laryunin
Keyword(s):  
Ray Tracing ◽  
Electron Density ◽  
Computer Time ◽  
Ionospheric Disturbances ◽  
Suggested Model ◽  
Layer Model ◽  
Calculation Time ◽  
Ray Paths ◽  
Parabolic Layer ◽  
Numerical Synthesis

Characteristic U-shaped traces cusps on ionograms have been identified as off-angle echoes from sloping electron density contours caused by the presence of traveling ionospheric disturbances (TIDs). Dynamics of the cusps is associated with horizontal drift of the disturbances. A potential for reducing calculation time in numerical synthesis of vertical ionograms is under discussion. Since numerical ray tracing is expensive in terms of computer time, we have developed simplified formulation for this study. The suggested model of compound parabolic layer allows us to analytically calculate ray paths. Changes in the shape of the ionogram cusp caused by varying TID characteristics are examined.

scholarly journals Numerical synthesis of ionograms in horizontally inhomogeneous ionosphere on the basis of compound parabolic layer model

2016 ◽  
Vol 2 (3) ◽  
pp. 74-86 ◽  
Author(s):  
Олег Ларюнин ◽  
Oleg Laryunin
Keyword(s):  
Ray Tracing ◽  
Electron Density ◽  
Temporal Evolution ◽  
Ionospheric Disturbances ◽  
Suggested Model ◽  
Layer Model ◽  
Computationally Intensive ◽  
Ray Paths ◽  
Parabolic Layer ◽  
Numerical Synthesis

Characteristic U-shaped traces (cusps) on ionograms have been identified as off-angle echoes from sloping electron density contours caused by the presence of traveling ionospheric disturbances (TIDs). Temporal evolution of the cusps is associated with horizontal drift of the disturbances. A potential for reducing calculation time in numerical synthesis of vertical ionograms is under discussion. Since numerical ray tracing is computationally intensive, we have developed simplified formulation for this study. The suggested model of compound parabolic layer allows us to analytically calculate ray paths. Changes in the shape of the ionogram cusp caused by varying TID characteristics are examined.

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)

Ray Tracing over a Transequatorial Path

1972 ◽  
Vol 50 (10) ◽  
pp. 976-990
Author(s):  
N. C. Gerson
Keyword(s):  
Ray Tracing ◽  
Density Gradient ◽  
Electron Density ◽  
Time Of Day ◽  
Horizontal Gradient ◽  
Strong Electron ◽  
Trapped Mode ◽  
Electron Density Gradient ◽  
The Magnetic Field ◽  
Ray Paths

Ray tracing procedures including the magnetic field were employed in an attempt to explain the mechanism of transequatorial propagation. The analysis was based upon (a) 41 MHz backscatter soundings south from Mayaguez, Puerto Rico and (b) vertical-incidence observations from the ionosonde chain near 75 °W. The latter were converted into electron density versus true height profiles. Data from both sources obtained during the same month were utilized.The computed ray tracings show the expected effects for refraction from the F layer: skip and horizon focusing, predawn blackout (0200–0600 LST), escape of all rays launched above 18° irrespective of time of day, diurnal variation in one-hop propagation distances, etc. Some calculated rays attain TE distances (6000–11 000 km without intervening ground reflections) at 0800 LST, 1600–2000 LST and 2400 LST. Others are trapped to distances exceeding 11 000 km at 0800 LST and 1400–2400 LST. Fair agreement is found between TE observations and TE calculated ray paths. Specific hours and distances showed some correlation. Qualitatively the general features of TE seem clarified. The calculations imply that rays launched within 9° of the horizon southward across the (magnetic) equator are responsible for TE propagation. These rays are injected into an ionospheric trapped mode by a strong electron density gradient. For a ray launched at the ground to propagate to TE distances, two requirements must be satisfied: (a) vertical refractivity gradients propitious for radiowave trapping, and (b) horizontal refractivity gradients allowing injection and ejection of the ray into and out of the duct. TE concurrences near 0800 LST may arise because of the rapid strengthening of the postsunrise electron density gradient near 20° geomagnetic. This strong horizontal gradient then disappears, possibly because of an atmospheric expansion, and does not reappear until late afternoon. The trapping conditions, however, remain from about sunrise to midnight.The results imply that at the same or a higher frequency more TE would be observed if more energy was emitted at lower launch angles.

scholarly journals Compatible analysis of vertical and oblique ionospheric sounding data

1996 ◽  
Vol 39 (4) ◽  
Author(s):  
I. V. Krasheninnikov ◽  
J. C. Jodogne ◽  
L. F. Alberca
Keyword(s):  
Ray Tracing ◽  
Electron Density ◽  
Ionospheric Sounding ◽  
Small Valley

Examples are presented of the ray-tracing synthesis of multifrequency Oblique Sounding (OS) data on the Dourbes (Belgium) í Roquetes (Spain) path using electron density height profiles derived from Vertical Sounding (VS) measurements at both terminals. Comparison with the measured OS ionograms provides a means of assessing the accuracy of the VS true-height procedure POLAN. Particular attention was paid to a consideration of the E-F1 valley, that as concluded is often less deep than currently supposed, when derived using both ordinary and extraordinary components of the VS ionograms. Also, it was found that the peak of the F1 -layer should be expressed more distinctly (sometimes with a small valley between the F1 and F2 layers) though the corresponding VS ionograms may have no discontinuity in the region.

scholarly journals RESPON TEC IONOSFER DI ATAS BANDUNG DAN MANADO TERKAIT FLARE SINAR-X MATAHARI KELAS M5.1 DAN M7.9 TAHUN 2015 (IONOSPHERIC TEC RESPONSE OVER BANDUNG DAN MANADO ASSOCIATED WITH M5.1 AND M7.9 CLASSES OF SOLAR FLARE XRAYS IN 2015)

2018 ◽  
Vol 14 (2) ◽  
pp. 111
Author(s):  
Sri Ekawati
Keyword(s):  
Time Delay ◽  
Solar Flare ◽  
Electron Density ◽  
Total Electron Content ◽  
Geomagnetic Latitude ◽  
Ionospheric Scintillation ◽  
Electron Content ◽  
Ionospheric Disturbances ◽  
X Rays ◽  
Total Electron

The solar flare is potential to cause sudden increase of the electron density in the ionosphere,particularly in D layer, known as Sudden Ionospheric Disturbances (SID). This increase of electron density occurs not only in the ionospheric D layer but also in the ionospheric E and F layers. Total Electron Content (TEC) measured by GPS is the total number of electrons from D to F layer. The aim of this research is to study the effect of solar flare x-rays, greater than M5 class in 2015, on ionospheric TEC over Bandung and Manado. This paper presents the preliminary result of ionospheric TEC response on solar flare occurrence over Indonesia. The ionospheric TEC data is derived from GPS Ionospheric Scintillation and TEC Monitor (GISTM) receiver at Bandung (-6.90o S;107.6o E geomagnetic latitude 16.54o S) and Manado (1.48o N; 124.85o E geomagnetic latitude 7.7o S). The solar x-rays flares classes analyzed where M5.1 on 10 March 2015 and M7.9 on 25 June 2015. Slant TEC (STEC) values where calculated to obtain Vertical TEC (VTEC) and the Differential of the VTEC (DVTEC) per PRN satellite for further analysis. The results showed that immediately after the flare, there where sudden enhancement of the VTEC and the DVTEC (over Bandung and Manado) at the same time. The time delay of ionospheric TEC response on M5.1 flare was approximately 2 minutes, then the VTEC increased by 0.5 TECU and the DVTEC rose sharply by 0.5 – 0.6 TECU/minutes. Moreover, the time delay after the M7.9 flare was approximately 11 minutes, then the VTEC increased by 1 TECU and the DVTEC rose sharply by 0.6 – 0.9 TECU/minutes. ABSTRAK Flare matahari berpotensi meningkatkan kerapatan elektron ionosfer secara mendadak, khususnya di lapisan D, yang dikenal sebagai Sudden Ionospheric Disturbances (SID). Peningkatan kerapatan elektron tersebut terjadi tidak hanya di lapisan D, tetapi juga di lapisan E dan F ionosfer. Total Electron Content (TEC) dari GPS merupakan jumlah banyaknya elektron total dari lapisan D sampai lapisan F. Penelitian ini bertujuan mengetahui efek flare, yang lebih besar dari kelas M5 tahun 2015, terhadap TEC ionosfer di atas Bandung dan Manado. Makalah ini merupakan hasil awal dari respon TEC ionosfer terhadap fenomena flare di atas Indonesia. Data TEC ionosfer diperoleh dari penerima GPS Ionospheric Scintillation and TEC Monitor (GISTM) di Bandung (-6,90o S; 107,60o E lintang geomagnet 16,54o LS) dan Manado (1,48oLU;124,85oBT lintang geomagnet 7,7o LS) dikaitkan dengan kejadian flare kelas M5.1 pada tanggal 10 Maret 2015 dan kelas M7.9 pada tanggal 25 Juni 2015. Nilai Slant TEC (STEC) dihitung untuk memperoleh nilai Vertical TEC (VTEC), kemudian nilai Differential of VTEC (DVTEC) per PRN satelit diperoleh untuk analisis selanjutnya. Hasil menunjukkan segera setelah terjadi flare, terjadi peningkatan VTEC dan DVTEC (di atas Bandung dan Manado) secara mendadak pada waktu yang sama. Waktu tunda dari respon TEC ionosfer setelah terjadi flare M5.1 adalah sekitar 2 menit, kemudian VTEC meningkat sebesar 0,5 TECU dan DVTEC meningkat secara tajam sebesar 0,5 – 0,6 TECU/menit. Sedangkan, waktu tunda setelah terjadi flare M7.9 adalah 11 menit, kemudian VTEC meningkat sebesar 1 TECU dan DVTEC meningkat secara tajam sebesar 0,6 – 0,9 TECU/menit.

scholarly journals Simulated high frequency ray paths considering traveling ionospheric disturbances

2020 ◽  
Vol 2 (4) ◽  
Author(s):  
Mariano Fagre ◽  
Bruno S. Zossi ◽  
Jaroslav Chum ◽  
Ana G. Elias
Keyword(s):  
High Frequency ◽  
Ionospheric Disturbances ◽  
Traveling Ionospheric Disturbances ◽  
Ray Paths

Identification and monitoring techniques of TIDs in the H2020 TechTIDE project

2020 ◽  
Author(s):  
David Altadill ◽  
Antoni Segarra ◽  
Estefania Blanch ◽  
José Miguel Juan ◽  
Dalia Buresova ◽  
...  
Keyword(s):  
South Africa ◽  
European Commission ◽  
Electron Density ◽  
Warning System ◽  
Ionospheric Disturbances ◽  
Operational System ◽  
Horizon 2020 ◽  
Research And Innovation ◽  
Methods And Techniques ◽  
Radio Signals

<p>Traveling Ionospheric Disturbances (TIDs) are wave-like propagating irregularities that alter the electron density environment and play an important role spreading radio signals propagating through the ionosphere.</p><p>TechTIDE project, funded by the European Commission Horizon 2020 research and innovation program, is establishing a pre-operational system to issue warnings of the occurrence of TIDs over the region extended from Europe to South Africa based on the reliability of a set of TID detection methodologies.</p><p>This contribution aims at presenting the different methods and techniques of identification and tracking the activity of TIDs and their respective performance, that serve to feed the warning system of TechTIDE.</p>

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