Amplitude scintillation index derived from C/N ₀ measurements released by common geodetic GNSS receivers operating at 1 Hz

Two widely used scintillation indexes S₄ and σ_φ are generated by dedicated ionospheric scintillation monitoring receivers (ISMRs), which typically have 50-Hz temporal resolution and thus require substantial memory capabilities. Taking into consideration the huge number of common Global Navigation Satellite System (GNSS) receivers, the derivation of a GNSS receiver-based scintillation index as a supplement to the ISMR indexes is expected to improve the study of ionospheric scintillation. We developed an amplitude scintillation index, S_{4 c}, which is derived from the carrier-to-noise density ratio (C/ N) data released by common geodetic GNSS receivers operating at 1-Hz. The reliability of the S_{4 c} index is compared with the typical scintillation index S₄ of three ISMRs located in Hong Kong and Brazil. The statistics indicate that during scintillation activity, the correlation coefficient between S_{4 c} (derived from common receivers) and S₄ (generated by ISMRs) is generally higher than 0.9. The reliability of S_{4 c} was also verified based on 1-year observations from two adjacent stations in Hong Kong, which are equipped with Leica GR50 and Septentrio PolaRxS Pro receivers, respectively. Long-term scintillation occurrence (S_{4 c} > 0.2 vs. S₄ > 0.2) rates show good agreement between S_{4 c} and S₄. In addition, two-dimensional S_{4 c} maps (1° × 1°) generated by GPS L1 and BDS B1 signals data collected at 117 continuous operation tracking stations in China clearly show post-sunset super plasma bubbles as the source of ionospheric scintillation during the main phase of the intense storm that occurred on September 8, 2017. These results demonstrate the feasibility of using the S_{4 c} index derived from the large volume of GNSS observations recorded by non-scintillation GNSS receivers for the study and monitoring of ionospheric scintillation.