scholarly journals Determination of a non-perturbed reference for a new version of the disturbance ionosphere index

2020 ◽  
Author(s):  
Giorgio Arlan da Silva Picanço ◽  
Clezio Marcos Denardini ◽  
Paulo Alexandre Bronzato Nogueira ◽  
Paulo França Barbosa-Neto ◽  
Láysa Cristina Araújo Resende ◽  
...  
Keyword(s):  
Dispersion Coefficient ◽  
Moving Average ◽  
Electron Content ◽  
Iri Model ◽  
Weather Event ◽  
Total Electron ◽  
Reference Determination ◽  
Space Weather Event

Abstract In the present work, we propose and evaluate a new method for the determination of a non-perturbed Total Electron Content (TEC) reference to apply it on a new version of the disturbance ionosphere index (DIX). This method is based on the calculation of a 3-hour moving average over the TEC obtained during a given reference day (named 3hMAQd method). In this context, the reference day is supposed to represent a quiet pattern considering geomagnetic and ionospheric features. To evaluate its performance, we compared the proposed method with TEC values obtained from monthly medians and the International Reference Ionosphere (IRI) model. The results are presented and discussed in terms of a dispersion coefficient between each method and the averaged TEC from the five quietest days of each month of 2015, over three Brazilian sites. Finally, we calculated the new DIX based on our proposed method and compared it with the original DIX values obtained during the extreme space weather event of St. Patrick’s Day magnetic storm (17–18 March 2015). Differences between the two DIX approaches are discussed to show the improvements in new DIX due to the application of the proposed non-perturbed reference. Moreover, results showed that the quality of the DIX calculation can be highly influenced by the non-perturbed reference determination. In this regard, the 3-hour moving average (3hMAQd) method showed to be a quite appropriate technique for the new DIX calculation, besides the 3-hour window matches with ordinary magnetic indices resolution (e.g. Kp and Ksa).

scholarly journals GPS normalization and preliminary modeling results of total electron content during a midlatitude space weather event

Radio Science ◽  
2001 ◽  
Vol 36 (2) ◽  
pp. 351-361 ◽  
Author(s):  
Jonathan J. Makela ◽  
Michael C. Kelley ◽  
Jan J. Sojka ◽  
Xiaoqing Pi ◽  
Anthony J. Mannucci
Keyword(s):  
Total Electron Content ◽  
Space Weather ◽  
Electron Content ◽  
Weather Event ◽  
Total Electron ◽  
Space Weather Event

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.

Estimating the quality of GEMTEC total electron content model in autonomous GNSS positioning

2015 ◽  
Vol 6 (3) ◽  
pp. 241-245 ◽  
Author(s):  
O. A. Gorbachev ◽  
V. T. Zalutskii ◽  
V. B. Ivanov ◽  
D. V. Khazanov ◽  
A. A. Kholmogorov
Keyword(s):  
Total Electron Content ◽  
Electron Content ◽  
Total Electron ◽  
Gnss Positioning ◽  
Content Model

scholarly journals Evaluating the Performance of IRI-2016 Using GPS-TEC Measurements over the Equatorial Region

Atmosphere ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1243
Author(s):  
Nouf Abd Elmunim ◽  
Mardina Abdullah ◽  
Siti Aminah Bahari
Keyword(s):  
Solar Activity ◽  
Early Morning ◽  
Equatorial Region ◽  
Activity Period ◽  
High Solar Activity ◽  
Electron Content ◽  
Dual Frequency ◽  
Iri Model ◽  
Total Electron ◽  
Solar Activity Period

Total electron content (TEC) is an important parameter in the ionosphere that is extensively used to study the variability of the ionosphere as it significantly affects radio wave propagations, causing delays on GPS signals. Therefore, evaluating the performance of ionospheric models is crucial to reveal the variety of ionospheric behaviour in different solar activity periods during geomagnetically quiet and disturbed periods for further improvements of the IRI model performance over the equatorial region. This research aimed to investigate the variations of ionospheric VTEC and observe the improvement in the performance of the IRI-2016 (IRI-2001, IRI01-corr, and NeQuick). The IRI-2016 was evaluated with the IRI-2012 using NeQuick, IRI-2001, and IRI01-corr topside electron density options. The data were obtained using a dual-frequency GPS receiver installed at the Universiti Utara Malaysia Kedah (UUMK) (geographic coordinates 4.62° N–103.21° E, geomagnetic coordinates 5.64° N–174.98° E), Mukhtafibillah (MUKH) (geographic coordinates 6.46° N–100.50° E, geomagnetic coordinates 3.32° S–172.99° E), and Tanjung Pengerang (TGPG) (geographic coordinates 1.36° N–104.10°E, geomagnetic coordinates 8.43° S–176.53° E) stations, during ascending to high solar activity at the geomagnetically quiet and disturbed periods in October 2011, March 2012, and March 2013. The maximum hourly ionospheric VTEC was observed during the post-noon time, while the minimum was during the early morning time. The ionospheric VTEC modelled by IRI-2016 had a slight improvement from the IRI-2012. However, the differences were observed during the post-noon and night-time, while the modelled VTEC from both IRI models were almost similar during the early morning time. Regarding the daily quiet and disturbed period’s prediction capability of the IRI-2016 and IRI-2012, IRI-2016 gave better agreement with the measured VTEC. The overall results showed that the model’s prediction performance during the high solar activity period in 2013 was better than the one during the ascending solar activity period. The results of the comparison between IRI-2016 and IRI-2012 in high solar activity exhibited that during quiet periods, all the IRI models showed better agreement with the measured VTEC compared to the disturbed periods.

scholarly journals On the validity of the ionospheric pierce point (IPP) altitude of 350 km in the Indian equatorial and low-latitude sector

2006 ◽  
Vol 24 (8) ◽  
pp. 2159-2168 ◽  
Author(s):  
P. V. S. Rama Rao ◽  
K. Niranjan ◽  
D. S. V. V. D. Prasad ◽  
S. Gopi Krishna ◽  
G. Uma
Keyword(s):  
Elevation Angle ◽  
Equatorial Region ◽  
Indian Region ◽  
Electron Content ◽  
Total Electron ◽  
Gps Satellites ◽  
Lower Elevation ◽  
Pierce Point ◽  
L1 And L2

Abstract. The GPS data provides an effective way to estimate the total electron content (TEC) from the differential time delay of L1 and L2 transmissions from the GPS. The spacing of the constellation of GPS satellites in orbits are such that a minimum of four GPS satellites are observed at any given point in time from any location on the ground. Since these satellites are in different parts of the sky and the electron content in the ionosphere varies both spatially and temporally, the ionospheric pierce point (IPP) altitude or the assumed altitude of the centroid of mass of the ionosphere plays an important role in converting the vertical TEC from the measured slant TEC and vice versa. In this paper efforts are made to examine the validity of the IPP altitude of 350 km in the Indian zone comprising of the ever-changing and dynamic ionosphere from the equator to the ionization anomaly crest region and beyond, using the simultaneous ionosonde data from four different locations in India. From this data it is found that the peak electron density height (hpF2) varies from about 275 to 575 km at the equatorial region, and varies marginally from 300 to 350 km at and beyond the anomaly crest regions. Determination of the effective altitude of the IPP employing the inverse method suggested by Birch et al. (2002) did not yield any consistent altitude in particular for low elevation angles, but varied from a few hundred to one thousand kilometers and beyond in the Indian region. However, the vertical TEC computed from the measured GPS slant TEC for different IPP altitudes ranging from 250 to 750 km in the Indian region has revealed that the TEC does not change significantly with the IPP altitude, as long as the elevation angle of the satellite is greater than 50 degrees. However, in the case of satellites with lower elevation angles (<50°), there is a significant departure in the TEC computed using different IPP altitudes from both methods. Therefore, the IPP altitude of 350 km may be taken as valid even in the Indian sector but only in the cases of satellite passes with elevation angles greater than 50°.

The three-dimensional ionospheric tomography in Japan by using the adaptive Kalman Filter algorithm

2020 ◽  
Author(s):  
Rui Song ◽  
Katsumi Hattori ◽  
Chie Yoshino
Keyword(s):  
Kalman Filter ◽  
Three Dimensional ◽  
Electron Content ◽  
Iri Model ◽  
Total Electron ◽  
Practical Applications ◽  
Annual Variations ◽  
Seasonal Characteristics ◽  
Electron Distributions ◽  
Priori Information

&lt;p&gt;&amp;#160; The three-dimensional (3-D) tomographic inversion is a crucial technique for imaging the ionospheric electron distributions (IEDs) on both the horizontal and vertical directions based on the total electron content (TEC) data. In this study, a regional 3-D tomography was realized in Japan using the Kalman Filter (KF) algorithm. In addition, to deduce the divergences, the adaptive Sage-Husa KF (SHKF) was proposed to determine the unknown priori information of the noise covariance encountered in the conventional KF (CKF). From this base, slant TEC (STEC) data observed by 55 GPS (Global Positioning System) receivers in the years of 2013 and 2018 was selected for IED reconstructions with the resolution 1&amp;#186;&amp;#215;1&amp;#186;&amp;#215;30 km in latitude, longitude and altitude, respectively. As for the ionospheric diurnal and annual variations, by comparing the F2 layer peak electron density (NmF2) simulated by SHKF, CKF, and the International Reference Ionosphere (IRI) model with the observed values detected by 4 Japanese ionosondes (Okinawa, Yamagawa, Kokubunji, and Wakkanai) during April 3-9, 2018 and 2013,&amp;#160;the Root-Mean-Square-Error (RMSE) and co-releation index (&amp;#961;) were adopted to evaluate the simulated effciency. Results showed that the least RMSE (0.3084 in 2018, 0.5397 in 2013) and the best &amp;#961; values (0.9517 in 2018, 0.9896 in 2013) were both given by the SHKF-CIT method. Then, seasonal characteristics were implemented on January 02, March 20, June 14 and September 24, 2018, where the variations of northern EIA, winter and semiannual anomalies were accurately captured by the SHFK method. Meanwhile, the recalculated TEC values as well as the inverted vertical profiles manifested that SHKF-based tomography was outperformed the other methods. In the end, taking a strong geomagnetic storm happened on 26 August, 2018 as an example, both the meridional and latitudinal (along 135&amp;#176;E and 35&amp;#176;N, respectively) IEDs displayed more significant promotions than IRI model, and the results indicates that the IED around Japan developed by SHKF-based tomography is promising for the ionospheric studies and practical applications.&lt;/p&gt;

Geometric determination of ionospheric total electron content from dual frequency radar sounding measurements

2019 ◽  
Vol 178 ◽  
pp. 104696 ◽  
Author(s):  
Kirk M. Scanlan ◽  
Cyril Grima ◽  
Gregor Steinbrügge ◽  
Scott D. Kempf ◽  
Duncan A. Young ◽  
...  
Keyword(s):  
Total Electron Content ◽  
Electron Content ◽  
Dual Frequency ◽  
Total Electron ◽  
Ionospheric Total Electron Content

scholarly journals Determinations of ionosphere and plasmasphere electron content for an African chain of GPS stations

2017 ◽  
Vol 35 (3) ◽  
pp. 599-612 ◽  
Author(s):  
Andrew J. Mazzella Jr. ◽  
John Bosco Habarulema ◽  
Endawoke Yizengaw
Keyword(s):  
Arabian Peninsula ◽  
Field Configuration ◽  
Electron Content ◽  
Total Electron ◽  
Gps Tec ◽  
The Difference ◽  
A Chain ◽  
Station Location ◽  
Latitudinal Profile

Abstract. The confluence of recent instrumentation deployments in Africa with developments for the determination of plasmasphere electron content using Global Positioning System (GPS) receivers has provided new opportunities for investigations in that region. This investigation, using a selected chain of GPS stations, extends the method (SCORPION) previously applied to a chain of GPS stations in North America in order to separate the ionosphere and plasmasphere contributions to the total electron content (TEC) during a day (24 July) in 2011. The results span latitudes from the southern tip of Africa, across the Equator, to the southern Arabian Peninsula, providing a continuous latitudinal profile for both the ionosphere and plasmasphere during this day.The peak diurnal vertical ionosphere electron content (IEC) increases from about 14 TEC units (1 TEC unit  =  1016 electrons m−2) at the southernmost station to about 32 TEC units near the geographic equator, then decreases to about 28 TEC units at the Arabian Peninsula. The peak diurnal slant plasmasphere electron content (PEC) varies between about 4 and 7 TEC units among the stations, with a local latitudinal profile that is significantly influenced by the viewing geometry at the station location, relative to the magnetic field configuration. In contrast, the peak vertical PEC varies between about 1 and 6 TEC units among the stations, with a more uniform latitudinal variation.Comparisons to other GPS data analyses are also presented for TEC, indicating the influence of the PEC on the determination of latitudinal TEC variations and also on the absolute TEC levels, by inducing an overestimate of the receiver bias. The derived TEC latitudinal profiles, in comparison to global map profiles, tend to differ from the map results only about as much as the map results differ among themselves. A combination of ionosonde IEC and alternative GPS TEC measurements, which in principle permits a PEC determination through their difference, was compared to the composite and separate ionosphere and plasmasphere contributions derived solely by the SCORPION method for one station. Although there is considerably more scatter in the PEC values derived from the difference of the GPS TEC and ionosonde IEC measurements compared to the PEC values derived by the SCORPION method, the average overhead values for this day are comparable for the two methods, near 2 TEC units, at the South African site examined.This initial investigation provides a basis for day-to-day TEC monitoring for Africa, with separate ionosphere and plasmasphere electron content determinations.

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