TEC Structure Diagnostics

Ionospheric structure is characterized by a hier-archy of spatial and temporal scales. The dynamic evolution of the large-scale structure is captured by global ionospheric models initiated with measured background conditions. However, electromagnetic wave (EM) diagnostics provide the most comprehensive global surveillance inputs, particularly total electron content (TEC) estimates derived from constellations of navigation satellites referred to collectively as GNSS. Managing global scale inputs necessarily constrains both resolution and the diagnostic measurements that might be exploited. Data bases that include only one-minute TEC samples with rate of change (ROTI), intensity scintillation, and phase scintillation measures are com-mon. However, GNSS frequencies were selected to minimize scintillation effects. TEC structure unaffected by diffraction is most often discarded, with the exception of spatial gradients that affect assisted GPS. This paper demonstrates a diffraction-free stochastic TEC structure measure, which can be extracted from the standard TEC estimates used for global monitoring or refined position estimation.