Studies of Equatorial Plasma Bubbles and the Associated Ionospheric TEC Gradients over South America

Rezy Pradipta, Patricia H. Doherty

Peer Reviewed

Abstract:	We present the results from our continuing efforts to experimentally investigate the occurrence pattern of large/steep ionospheric total electron content (TEC) gradients over the Brazilian airspace. These steep TEC gradients are associated with the equatorial plasma bubbles (EPBs) that regularly appear in the nighttime ionosphere over the low-latitude regions. The main focus of our investigation is the Brazilian region, where GPS TEC data from the RBMC network (provided by Instituto Brasileiro de Geografia e Statistica, IBGE) can be used to study the aforementioned bubble-related ionospheric gradients. From our previous work, the analysis of Brazilian GPS TEC data collected in 2014/2015 had revealed that the distribution of TEC gradient magnitudes over this region follow some form of double-power-law with certain exponents. In this study, those past findings are verified using the more recent Brazilian GPS TEC data from 2015/2016. The general qualitative features found in the distribution function of the TEC gradient magnitudes from the 2014/2015 and 2015/2016 data are generally consistent. The power-law exponents derived from fitting are relatively close, although there are some discrepancies (n1=-2.4 and n2=-4.0 for the 2014/2015 data; compared to n1=-2.3 and n2=-4.8 for the 2015/2016 data). Finally, in this paper we also present some data from ionosonde measurements for a comparison with the GPS TEC observation of EPBs in the region. This data comparison helps illustrate the correspondence between bubble-related TEC gradients and the spread-F echoes (indicating plasma turbulence) that can be seen in the ionosonde observations.
Published in:	Proceedings of the 29th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2016) September 12 - 16, 2016 Oregon Convention Center Portland, Oregon
Pages:	1672 - 1679
Cite this article:	Pradipta, Rezy, Doherty, Patricia H., "Studies of Equatorial Plasma Bubbles and the Associated Ionospheric TEC Gradients over South America," Proceedings of the 29th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2016), Portland, Oregon, September 2016, pp. 1672-1679. https://doi.org/10.33012/2016.14770
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