Validation of nequick2 and cor2 topside options in IRI-2020 using GPS-derived TEC over low-latitude regions of Africa and south America.
| dc.contributor.author | Kipruto, Moses | |
| dc.date.accessioned | 2026-10-15T12:52:15Z | |
| dc.date.available | 2026-10-15T12:52:15Z | |
| dc.date.issued | 2026 | |
| dc.description | Dissertation | |
| dc.description.abstract | The International Reference Ionosphere 2020 (IRI-2020) model offers four topside electron density options namely; NeQuick2 (NeQ), IRI-2001, IRI-2001cor and COR2. This study evaluates the ability of the NeQ and COR2 topside options of IRI-2020 to reproduce GPS-derived TEC over selected low-latitude regions of Africa and South America during ascending phase of solar cycle 25 under both quiet and geomagnetically disturbed conditions. The GPS TEC observations from Addis Ababa, Malindi, Libreville, Brasília, Belém, and Porto Velho were assessed against TEC estimates from IRI-2020 topside options for years 2020, 2022, and 2024, representing low, medium, and high solar activity conditions, respectively. The Percentage root mean square error (PRMSE) was used to quantify the performance of NeQ and COR2 options. The performance of NeQ and COR2 were observed to vary with latitude, season, intensity of storms and solar activity. During low and medium solar activity, COR2 demonstrates stronger performance at the trough stations across all seasons with COR2 best performance of 17.7% at BELE and 15.3% at ADIS in June during low and medium solar activity conditions whereas NeQ performs better at the crest stations across all seasons and solar activity levels with the lowest PRMSE value of 7.6% in March of medium solar activity conditions. Under high solar activity, however, NeQ’s better performance extends to the trough stations as well achieving the lowest PRMSE value of 18.7% in September equinox. The COR2 outperforms NeQ during weak storm of 20 April 2020 and moderate storm of 3 March 2024, while NeQ is more robust under strong geomagnetic storm of 11 May 2024. Best performance of NeQ (16.1%) option was recorded in day 134 and worst performance of COR2 (200.4%) was observed in Day 132 over BRAZ during strong storm. Both top side options performed better at EIA trough regions than crest regions during low and medium solar activity. The high accuracy applications require regional validation and context specific selection of the IRI- 2020 topside electron density options, as no single model options performs consistently well across all regions, solar activity and geomagnetic conditions. Future studies could explore whether combining the NeQ and COR2 topside approaches may provide useful improvements under different geophysical conditions, with its effectiveness requiring further investigation and validation. | |
| dc.description.sponsorship | Dr. Geoffrey Andima ; Dr. Valence Habyarimana ; Busitema University | |
| dc.identifier.citation | Kipruto, M. (2026). Validation of nequick2 and cor2 topside options in IRI-2020 using GPS-derived TEC over low-latitude regions of Africa and south America. [Unpublished dissertation]. Busitema University. | |
| dc.identifier.uri | https://bdears.busitema.ac.ug/handle/123456789/10983 | |
| dc.language.iso | en | |
| dc.publisher | Busitema University | |
| dc.title | Validation of nequick2 and cor2 topside options in IRI-2020 using GPS-derived TEC over low-latitude regions of Africa and south America. | |
| dc.type | Other |