Researchers provide vital link between theory and data for GPS signal fluctuations

ISR researchers Charlie Carrano, Keith Groves, and Chuck Rino recently published their new theoretical model to relate a widely used statistical measure (ROTI) of fluctuations in total electron content to statistical measures of ionospheric irregularities and the scintillations they produce. This model includes several effects not previously accounted for quantitatively. The model was validated using measurements collected at Ascension Island, a small island midway between Africa and South America near the Equator.

The figure shows the Rate of change of TEC index (ROTI) and scintillation index (S₄) as a function of local time (LT) for a GPS satellite signal recorded at Ascension Island. The S₄ values predicted from ROTI (red) compare very well with direct measurements of S₄ (black). For additional details, see the full paper at

https://doi.org/10.1029/2018JA026353