scholarly journals Electrodynamical response of the Indian low-mid latitude ionosphere to the very large solar flare of 28 October 2003 – a case study

2009 ◽  
Vol 27 (10) ◽  
pp. 3853-3860 ◽  
Author(s):  
G. Manju ◽  
T. K. Pant ◽  
C. V. Devasia ◽  
S. Ravindran ◽  
R. Sridharan
Keyword(s):  
Solar Flare ◽  
Equatorial Electrojet ◽  
Electron Content ◽  
Recombination Rates ◽  
Total Electron ◽  
Peak Enhancement ◽  
Global Positioning ◽  
System Data ◽  
Current Systems

Abstract. The electrodynamic effects on the low-mid latitude ionospheric region have been investigated using GPS (global positioning system) data, ionosonde data and ΔH values, during the very large solar flare (X17.2/4B) of 28 October 2003. The results bring out the flare induced unusual behaviour of the equatorial ionosphere on this day just prior to sunset. The important observations are i) Large and prolonged Ne enhancements observed from ionosonde data just after the flare-related peak enhancement in EUV flux. The observed enhancement in Ne is due to the increase in ionization production due to the enhanced EUV flux and the persistence of the enhancement is probably due to the prompt penetration related upliftment of the F layer (just prior to the flare peak phase) to higher altitudes, where recombination rates are lower. ii) A significant enhancement in total electron content (TEC) (~10 TEC units) at regions around the Equatorial Ionization Anomaly (EIA) crest region (Ahmedabad) during the flare in association with the flare related EUV flux enhancement. iii) Similar enhancements seen at stations of Jodhpur and Delhi in the mid latitude sector. iv)The flare related flux enhancements in different longitude sectors in the equatorial electrojet region have been shown to produce positive and negative variations in electrojet strength indicating the presence of current systems having positive and negative polarities in different longitude sectors. Thus the flare effect reveals the longitudinal variation of the counter electrojet events in the Equatorial Electrojet (EEJ) region.

scholarly journals An investigation of solar flare effects on equatorial ionosphere and thermosphere using co-ordinated measurements

2019 ◽  
Vol 71 (1) ◽  
Author(s):  
S. G. Sumod ◽  
Tarun Kumar Pant
Keyword(s):  
Solar Flare ◽  
Equatorial Electrojet ◽  
Field Measurements ◽  
Equatorial Ionosphere ◽  
Electron Content ◽  
Total Electron ◽  
Equatorial Station ◽  
Solar Flare Effects ◽  
Coupling Processes ◽  
Class Flare

AbstractThe response of equatorial ionosphere–thermosphere system to the X3.8 solar flare of January 17, 2005 has been studied using the coordinated measurements of GPS-derived Total Electron Content (TEC), OI 630.0 nm dayglow and magnetic field measurements over a dip equatorial station Trivandrum (8.5° N, 77° E, dip 0.5° N), in India. It has been observed that Equatorial Electrojet (EEJ) as inferred using the ground-based magnetometers and GPS-derived TEC measurements show prompt enhancements during the peak flare, as expected. Interestingly, the temporal evolution of TEC at different latitudes revealed that the X3.8 class flare produced significant weakening of the plasma fountain and hence in the Equatorial Ionization Anomaly (EIA). Furthermore, the response of OI 630.0 nm dayglow during the flare is found to be strongly affected by the prevailing electrodynamics. The plausible physical mechanism for these effects is discussed in context of the current understanding of the neutral and electrodynamical coupling processes.

scholarly journals Response of High Latitude Ionospheric TEC to Enhanced Radiation Fluxes during the Major Solar Flare Events

2013 ◽  
Vol 6 (1) ◽  
pp. 43-49 ◽  
Author(s):  
P. K. Purohit ◽  
A. A. Mansoori ◽  
P. A. Khan ◽  
P. Bhawre ◽  
S. C. Tripathi ◽  
...  
Keyword(s):  
Solar Flare ◽  
Total Electron Content ◽  
High Latitude ◽  
Solar Disc ◽  
Electron Content ◽  
Central Meridian ◽  
Total Electron ◽  
X Ray ◽  
Radiation Fluxes ◽  
Peak Enhancement

We have investigated the response of ionosphere to major solar flare events that occurred during 1998 to 2011. The effect of enhanced radiation fluxes in the X-ray and EUV band on the GPS derived Total Electron Content (TEC) is examined. The data of X-ray flux from Geostationary Operational Environment Satellite (GOES) and EUV flux from Solar EUV Monitor (SEM) onboard SOHO spacecraft were correlated with the Total Electron Content (TEC) data of a high latitude station, Davis (68.570S, 77.960E). We found that peak intensities of X-ray and EUV flux correlate very well with the peak values of TEC. We also studied the correlation of peak enhancement of these fluxes with the peak enhancement of TEC and found that peak enhancement of these fluxes correlate highly with the peak enhancement of TEC than with the peak values themselves. It is also found that correlation is extraordinarily improved when these fluxes are multiplied by Cos(CMD) where CMD is Central Meridian Distance on the solar disc, thereby showing that the location of flares on the solar disc plays an important role while investigating the ionospheric influences of solar flares.  Keywords: Ionosphere; TEC; CMD; Solar Flare. © 2014 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. doi: http://dx.doi.org/10.3329/jsr.v6i1.14100 J. Sci. Res. 6 (1), 43-49 (2014)

scholarly journals Case study on total electron content enhancements at low latitudes during low geomagnetic activities before the storms

2008 ◽  
Vol 26 (4) ◽  
pp. 893-903 ◽  
Author(s):  
◽  
◽  
◽  
Keyword(s):  
Total Electron Content ◽  
Geomagnetic Activity ◽  
Electron Content ◽  
Low Latitude ◽  
Total Electron ◽  
Defense Meteorological Satellite Program ◽  
Low Latitudes ◽  
Global Ionospheric Maps ◽  
Geomagnetic Activities

Abstract. Sometimes the ionospheric total electron content (TEC) is significantly enhanced during low geomagnetic activities before storms. In this article, we investigate the characteristics of those interesting TEC enhancements using regional and global TEC data. We analyzed the low-latitude TEC enhancement events that occurred around longitude 120° E on 10 February 2004, 21 January 2004, and 4 March 2001, respectively. The TEC data are derived from regional Global Positioning System (GPS) observations in the Asia/Australia sector as well as global ionospheric maps (GIMs) produced by Jet Propulsion Laboratory (JPL). Strong enhancements under low geomagnetic activity before the storms are simultaneously presented at low latitudes in the Asia/Australia sector in regional TEC and JPL GIMs. These TEC enhancements are shown to be regional events with longitudinal and latitudinal extent. The regions of TEC enhancements during these events are confined at narrow longitude ranges around longitude 120° E. The latitudinal belts of maxima of enhancements locate around the northern and southern equatorial ionization anomaly (EIA) crests, which are consistent with those low-latitude events presented by Liu et al. (2008). During the 4 March 2001 event, the total plasma density Ni observed by the Defense Meteorological Satellite Program (DMSP) spacecraft F13 at 840 km altitude are of considerably higher values on 4 March than on the previous day in the TEC enhanced regions. Some TEC enhancement events are possibly due to contributions from auroral/magnetospheric origins; while there are also quasi-periodic enhancement events not related to geomagnetic activity and associated probably with planetary wave type oscillations (e.g. the 6 January 1998 event). Further investigation is warrented to identify/separate contributions from possible sources.

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 Comparison of GPS TEC with IRI models of 2007, 2012, AND 1 2016 over Sukkur, Pakistan

2020 ◽  
Vol 1 (1) ◽  
pp. 1-10
Author(s):  
Adil Hussain ◽  
Munawar Shah
Keyword(s):  
Global Positioning System ◽  
Electron Content ◽  
Iri Model ◽  
Low Latitude ◽  
Total Electron ◽  
Gps Tec ◽  
Global Positioning ◽  
Radio Signals ◽  
Ionospheric Scintillations ◽  
Latitude Region

The international reference ionosphere (IRI) models have been widely used for correcting the ionospheric scintillations at different altitude levels. An evaluation on the performance of VTEC correction from IRI models (version 2007, 2012 and 2016) over Sukkur, Pakistan (27.71º N, 68.85º E) is presented in this work. Total Electron Content (TEC) from IRI models and GPS in 2019 over Sukkur region are compared. The main aim of this comparative analysis is to improve the VTEC in low latitude Sukkur, Pakistan. Moreover, this study will also help us to identify the credible IRI model for the correction of Global Positioning System (GPS) signal in low latitude region in future. The development of more accurate TEC finds useful applications in enhancing the extent to which ionospheric influences on radio signals are corrected. VTEC from GPS and IRI models are collected between May 1, 2019 and May 3, 2019. Additionally, Dst and Kp data are also compared in this work to estimate the geomagnetic storm variations. This study shows a good correlation of 0.83 between VTEC of GPS and IRI 2016. Furthermore, a correlation of 0.82 and 0.78 is also recorded for IRI 2012 and IRI 2007 respectively, with VTEC of GPS. The IRI TEC predictions and GPS-TEC measurements for the studied days reveal the potential of IRI model as a good candidate over Pakistan.

Variability of GPS-derived Ionospheric TEC over Nigeria during a year of low solar activity

2020 ◽  
Author(s):  
G.A. Akinyemi ◽  
L.B. Kolawole ◽  
O.F. Dairo ◽  
Alexander A. Willoughby ◽  
R.B. Abdulrahim ◽  
...  
Keyword(s):  
Global Positioning System ◽  
Electron Content ◽  
Gps Receiver ◽  
Total Electron ◽  
Ionospheric Total Electron Content ◽  
Global Positioning ◽  
Variability Index ◽  
Gnss Network ◽  
Tec Variability ◽  
Anomaly Region

An investigation on the diurnal and seasonal variability of ionospheric Total Electron Content (TEC) over Nigeria is carried out in this study using Global Positioning System (GPS) observable. Nigeria coordinates fall within the trough of equatorial ionization anomaly region of African sector. The TEC data used were obtained from the ground-based GPS receiver stations of the Nigerian GNSS network of stations (NIGNET). The stations with their respective geomagnetic latitudes are Abuja (−1.64º), Yola (−1.32º), Zaria (−0.13º) and Kebbi (0.72º). The results of the diurnal analysis of the relative variability index (VD) revealed higher nighttime values than daytime values. The diurnal variation of VD also showed two conspicuous peaks: the post-midnight and the post-sunset. The diurnal-seasonal variation does not reveal any consistent pattern (no particular season leads the others throughout). On the average, considering all the seasons together maximum TEC variability occurred in Zaria (62%) and least in Yola (54%). Seasonally, maximum VD was recorded during March equinox and the least was recorded during December equinox.

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