Systematic Solar Cycle Variation of the Ionospheric TEC Gradient Magnitude Distribution over the Brazilian Airspace

Rezy Pradipta, Endawoke Yizengaw, and Patricia H. Doherty

Abstract:	Using a chain of ground-based GPS receiver stations from the RBMC network, we studied the distribution of ionospheric total electron content (TEC) gradient magnitudes over the Brazilian airspace and its variation throughout the maximum phase of Solar Cycle 24. The GPS receiver stations used for this study form an east-west chain along the southern crest of the equatorial ionization anomaly (EIA), where we may expect the largest TEC gradient magnitudes and the most severe cases of ionospheric scintillations to occur due to equatorial plasma bubbles (EPB). Multiyear GPS observation data from 2011 to 2016 were analyzed for the ionospheric TEC gradient calculations. The calculated TEC gradient values from January-March period in each year were subsequently aggregated to construct the distribution histogram of the ionospheric TEC gradient magnitudes. We found that the ionospheric TEC gradient magnitude distribution in each year follows a form of double-power-law distribution with a clearly visible break, in general agreement with a number of previously reported results [Pradipta and Doherty, 2016a, 2016b; Pradipta et al., 2016]. Furthermore, we also found that the two exponents of the aforementioned double-power-law vary systematically from one year to the next following the evolution of the solar cycle. In the year(s) when the sunspot number was higher, the tail of the TEC gradient magnitude distribution shifted upward, indicating a more frequent occurrence of extreme TEC gradients over the area. It is hoped that these findings would be useful for projecting the level of threats to GBAS/SBAS services at various phases of the solar cycle.
Published in:	Proceedings of the 31st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2018) September 24 - 28, 2018 Hyatt Regency Miami Miami, Florida
Pages:	4144 - 4150
Cite this article:	Pradipta, Rezy, Yizengaw, Endawoke, Doherty, Patricia H., "Systematic Solar Cycle Variation of the Ionospheric TEC Gradient Magnitude Distribution over the Brazilian Airspace," Proceedings of the 31st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2018), Miami, Florida, September 2018, pp. 4144-4150. https://doi.org/10.33012/2018.15923
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