Highlights GPS-TEC variability is probed during the high solar activity period 2012–2015. IRI and SPIM/IRI-Plas model performances show discrepancy in diurnal variability. Results suggest revision of storm models in IRI-2016 and SPIM/IRI-Plas 2017. GPS-TEC ingestion into SPIM/IRI-Plas 2017 considerably improves the performance. It emphasizes plausible optimization of SPIM/IRI-Plas 2017 coefficients in future.

    Abstract This paper focuses on the variability of ionospheric Total Electron Content (TEC) over low latitude Indian sub-continental region during the geomagnetically quiet and disturbed periods under the high solar activity phase (years 2012–2015) of the 24th solar cycle. The study is carried out with Global Positioning System (GPS) observations from four International Global Navigation Satellite System Service (IGS) stations, aligned in a longitudinal fashion from magnetic equatorial location to beyond Equatorial Ionization Anomaly (EIA) crest latitude across Indian longitude. The corresponding values are extracted by four-point Inverse Distance Weighted (IDW) interpolation of TEC from IGS-Global Ionosphere Maps (IGS-GIMs) and by running the globally acceptable empirical ionosphere models: International Reference Ionosphere (IRI-2016) and Standard Plasmasphere Ionosphere Model (SPIM/IRI-Plas 2017). Apart from the manifestations of broader daytime diurnal peak TEC, its double-humped structure, EIA, winter anomaly/seasonal anomaly, and storm-time alterations, the study tried to probe the model performances with respect to the GPS based TEC observations. While GIM-TEC portrays a systematically varying magnitude for a particular location, the underestimation (equatorial latitude) and overestimation (higher latitude) is being witnessed by IRI model in the diurnal and seasonal variations. However, SPIM-2017 manifests an all-time overestimated TEC irrespective of time and season though the variation pattern replicates the GPS-TEC observations. Concerning storm-time response, the sub-models embedded in IRI/SPIM hardly reveal a remarkable alteration in the regular TEC variation except for trivial divergences in the IRI outcomes. In spite of compelling timely improvements in climatological representations, the limited storm-time response in IRI/SPIM models attracts the attention for further improvements in the existing primitive storm model specifications. Moreover, the intentional ingestion of external GPS-TEC into the SPIM-2017 model resulted in an exceptional improvement (about 75%) in the model prediction with improved correlation coefficients. The results from this study would complement a realistic global climatological representation of ionosphere for a faithful estimation of ionospheric delay error in radio signal applications. Finally, our results emphasize the flexibility of scopes in SPIM-2017 model towards external ingestions of observed ionospheric parameters. The ingestion of optional inputs convolved with rescaling and optimization would significantly improve the model performances for global climatological as well as storm-time ionospheric representation.


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    Titel :

    Performance analysis of quiet and disturbed time ionospheric TEC responses from GPS-based observations, IGS-GIM, IRI-2016 and SPIM/IRI-Plas 2017 models over the low latitude Indian region


    Beteiligte:

    Erschienen in:

    Advances in Space Research ; 64 , 10 ; 2026-2045


    Erscheinungsdatum :

    2019-03-23


    Format / Umfang :

    20 pages




    Medientyp :

    Aufsatz (Zeitschrift)


    Format :

    Elektronische Ressource


    Sprache :

    Englisch