A scintillation caused by ionospheric irregularities during Global Navigation Satellite System (GNSS) measurements is detected. A first input GNSS measurement corresponding to a navigation satellite and corresponding to a first carrier frequency and a second GNSS measurement corresponding to the navigation satellite and corresponding to a second carrier frequency, in which the second carrier frequency is different from the first carrier frequency, are received. A geometry-free combination (GFC) parameter based at least in part on the first input GNSS measurement, the second input GNSS measurement, the first carrier frequency, and the second carrier frequency is calculated. The occurrence of a scintillation caused by an ionospheric irregularity is determined based at least in part on the GFC parameter. In an embodiment of the invention, the dispersion of the GFC parameter over a specified time interval is determined. A scintillation is detected if the dispersion exceeds a specified threshold value.