GPS data collected from the global GPS network are being used to detect and to measure ionospheric irregularities and scintillation effects. These can be achieved through the measurements of signal phase fluctuations. The fluctuations can be characterized by the rate of TEC index (ROTI) based on the standard deviation of ROT change over a time interval. The following examples are measured during a major geomagnetic storm in November of 1993.

Phase fluctuations at low latitudes (site location: 5.3N, 307.2E)
Phase fluctuations at high latitudes (site location: 62.3N, 245.5E)

Snapshots of global ionospheric irregularities can be shown on a ROTI map, which is produced continuously for every 15-minute interval. These examples of ROTI maps show the evolution of ionospheric irregularities on January 10, 1997, during a geomagnetic storm.