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Regional ionospheric model response of geomagnetic storm during March 2015 using data fusion mechanism: GPS, COSMIC RO and SWARM

Emmela Suneetha, Ratnam Devanaboyina Venkata

Acta Geophysica

2023

Vol. 71, no. 1

553--566

The total electron content (TEC) maps are chosen as the elementary structures to provide ionospheric corrections for improving the positional accuracy for Global Navigational Satellite Systems (GNSS) users. Availability of total electron content data from a multi-constellation of satellite systems and various ground-based instruments possess an ability to monitor, nowcast and forecast the behavior of the ionosphere region. Conversely, combining ionospheric TEC data from different temporal and spatial scales is a difficult task to augment either ground or space-based ionospheric model's accuracy. And hence, a method like data fusion is essential to illustrate the ionospheric variability and to improve the accuracy of ionospheric models under equatorial ionization anomaly (EIA) conditions. This paper presented the weighted least square data fusion method with multi-instrument TEC data to analyze the EIA TEC structures in the low-latitude Indian region. Both ground-based (GPS TEC from 26 stations in the Indian region) and space-based (FORMOSAT-3/COSMIC RO and SWARM mini satellite constellation) observations are used for the analysis. The spherical harmonic function (SHF) model of order 2, which gives nine SHF coefficients, is implemented. The analysis illustrates that the SHF coefficients followed by TEC data fusion would be useful to investigate the entry, occupancy and exit TEC structures of EIA during geomagnetic storm conditions.

Correlation analysis of vertical total electron content

Arslan N.

Acta Geophysica

2011

Vol. 59, no. 2

377-397

It is necessary to model and analyze the ionospheric effects due to a direct relationship between Global Positioning System (GPS) applications and changes in the ionosphere. In order to monitor these changes, the ionosphere can be represented by the vertical total electron content (VTEC) which can be used to analyze ionospheric conditions from a variety of stations. In this study, 21 stations were used to carry out analysis and estimation of VTEC. Three days during a geomagnetic storm, namely, 7, 8, and 9 January 2005, are chosen for investigation. In addition, the de-correlation time of the VTEC was estimated to define ionospheric variations in time using autocorrelation analysis. The de-correlation time of the ionosphere is based on correlation times estimated by using autocorrelation functions. From the high-latitude stations, the mean of the correlation times decreased from 8 to 6 epochs during a storm. In this time period, it was found from the station results that the ionosphere was more affected at the high-latitude than at the mid-latitude region.