TEC prediction performance of the IRI-2012 model over Ethiopia during the rising phase of solar cycle 24 (2009–2011)

Tariku, Yekoye Asmare

doi:10.1186/s40623-015-0312-1

Cited by 20 publications

(8 citation statements)

References 30 publications

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“…Kumar on the other hand, showed that the IRI-2012 model overestimates the measured VTEC during low and high solar activity phases in equatorial regions [4]. However, in the Ethiopian region, Tariku stated that the model performed better during low solar activity when compared to high solar activity [27,28]. Elmunim investigated the performance of the IRI-2012 model in Langkawi, Malaysia [29].…”

Section: Introductionmentioning

confidence: 99%

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

2021

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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.

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Section: Introductionmentioning

confidence: 99%

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

2021

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“…However, previous ionospheric studies have shown that the IRI 2012 model data for the equatorial ionosphere of the African longitude sector have a good correlation with measured data. For example, Tariku () showed that the IRI‐2012 model with the NeQuick topside option was generally good in estimating the total electron content derived from GPS measurements.…”

Section: Ray Tracing Simulationmentioning

confidence: 99%

A Ray Tracing Simulation of HF Ionospheric Radar Performance at African Equatorial Latitudes

et al. 2020

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High‐frequency (HF) coherent radars are widely applied for studying electrodynamic processes in the Earth's upper atmosphere and ionosphere. Super Dual Auroral Radar Network (SuperDARN) is an international network of such radars located at high‐ and middle‐latitude regions in the Northern and Southern Hemispheres. A major criterion of the HF coherent radar technique entails that the HF waves propagate orthogonal to the geomagnetic field lines (aspect angle ≤1°) in the ionospheric irregularity region from where backscatter originates. In this paper we present an HF ray tracing simulation of the performance of three proposed equatorial HF radar systems for the African equatorial sector. We use a number of realistic average ionospheres deduced from the International Reference Ionosphere (IRI) 2012 model and magnetic field geometries from the International Geomagnetic Reference Field (IGRF) to determine likely propagation paths and orthogonality conditions for such radar systems. The east‐west azimuth ( ∼25° range) has a significant likelihood of achieving a SuperDARN‐type backscatter in the African equatorial sector, mainly due to the prevailing magnetic field geometry. This analysis provides a feasibility study for developing a SuperDARN‐like radar for studying the equatorial ionosphere over the African longitude sector, for example, in determining the technical radar characteristics such as preferable operating frequencies, antenna boresight orientation, and azimuth coverage and provides a simulation of the expected localization of radar backscatter as a function of radar location and beam direction, as well as the time of day, season, and sunspot number.

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“…Comparing ionospheric model estimations to real-time experimental data (from equipment) is a prevalent approach used by ionospheric researchers to assess model accuracy and validate them for useful applications (Migoya-Orué et al, 2008;Rabiu et al, 2014;Tariku, 2015;Cherniak and Zakharenkova, 2016;Okoh et al, 2018;Sharma et al, 2018). Researchers (Ezquer et al, 2018;Okoh et al, 2018;Teriku, 2020) conducted a comparison of different ionospheric TEC models (IRI, IRI-plas, and NeQ-2) using GNSS measurements and concluded that NeQ-2 performs better than other models regardless of time or location.…”

Section: Introductionmentioning

confidence: 99%

A study of vTEC above Nepal exploring different calibration techniques, including a comparison with the NeQuick-2 model

Poudel

Silwal

Ghimire

et al. 2022

Astrophys Space Sci

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In this paper, we investigate the performance of the NeQuick 2 (NeQ-2) model with respect to Ciraolo's and Gopi's derived ionospheric vertical TEC (vTEC) during the years 2014 and 2015.GPS observables derived from dual-frequency receivers over western Nepal (Simikot, Bhimchula and Nepalganj) are processed to obtain the experimental vTEC utilizing Gopi's and Ciraolo's calibration procedures. The monthly and seasonal behavior of vTEC obtained from each calibration technique is compared with the vTEC obtained from the NeQ-2 model during a quiet period. It is observed that the vTEC value obtained from all studied approaches started to increase from 00:00 UT, reached a maximum around 08:00 UT, followed by declination, attaining a minimum value around 23:00 UT. Moreover, a comparative study showed that vTEC computed using the Ciraolo calibration technique overestimates GPS vTEC, calculated in all hours and months by Gopi's approach. In the spring and summer, vTEC derived using Ciraolo's TEC calibration overestimates NeQ-2 and underestimates it in the autumn and winter. Except for a few day hours in March and April 2014 (solar maximum), NeQ-2 prediction overestimated Gopi calibrated GPS vTEC. In daytime hours, a considerable difference is noted between one vTEC estimate with respect to another. NeQ-2 model vTEC is favourably associated with GPS vTEC obtained using the Gopi procedure in spring and correlates with the Ciraolo technique in autumn. Two GPS vTEC estimations demonstrate superior consistency in summer and winter 2 seasons over all studied stations. The study on geomagnetically disturbed conditions demonstrates that NeQ-2 is not responding to the storm influence. However, the mean absolute difference between NeQ-2 prediction and GPS vTEC procured through the Gopi approach is less on the storm event day. By contrast, it is discovered less by the Ciraolo technique when the storm is recovering (except for few cases).

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TEC prediction performance of the IRI-2012 model over Ethiopia during the rising phase of solar cycle 24 (2009–2011)

Cited by 20 publications

References 30 publications

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

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

A Ray Tracing Simulation of HF Ionospheric Radar Performance at African Equatorial Latitudes

A study of vTEC above Nepal exploring different calibration techniques, including a comparison with the NeQuick-2 model

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