Stochastic TEC Structure Characterization

The global navigation satellite systems provide high‐quality total electron content (TEC) measurements that are used routinely for ionospheric diagnostics. Large‐scale TEC structure is a critical input for maintaining global ionospheric models. However, residual stochastic TEC structure is typically discarded as a phase‐scintillation‐induced error. In this paper we show that the phase‐scintillation errors are a negligibly small fraction of the stochastic TEC component for most global navigation satellite system operating conditions. With three‐frequency GPS satellite measurements, two independent TEC measurements can be compared to bound the scintillation‐induced errors. Data analysis and simulations show that scintillation‐induced errors are a small fraction of one TEC unit as long as the lower contributing frequency S 4 index is less than 0.5. To the extent that scintillation‐induced errors are negligible, spectral analysis of stochastic TEC provides a direct measure of path‐integrated structure. Irregularity parameter estimation can be used to estimate power law parameters, which in turn can be interpreted with a new global ionospheric structure model. We present a summary analysis of month‐long series of continuous measurements at Poker Flat, Alaska. The analysis confirms the generally accepted single power law model for high‐latitude structure. A small fraction of the measurements indicate an outer‐scale transition at approximately 17 km. The general pattern of the structure occurrence is consistent with auroral‐zone activity.