Observation of Ionospheric Scintillation Using GNSS-Reflectometry Measurement from Spire Global’s CubeSats

In this paper, we present a case study of ionospheric scintillation observed by low-cost CubeSat-based global navigation satellite system reflectometry (GNSS-R) measurements. The GNSS-R data used in this work are from Spire Global CubeSats. A GNSS-R event with its specular point track over the sea south of Singapore contains sufficient coherent energy that enable the ionospheric scintillation observations. Clear phase fluctuations are shown at the ionospheric piercing points (IPP) located over the sea south of Singapore. The phase fluctuations are quantified through the phase scintillation index (sigma phi), and scintillation index (S4). Our analysis indicates that the magnitudes of the filtered phase fluctuation are ~18 cm on L2-band and ~11 cm on L1-band, respectively. The maximum values of sigma phi are ~6 cm and ~4 cm on L2-band and L1-band, respectively. The S4 values reach ~0.65 in this case. Validation through nearby Radio Occultation (RO) measurements from FORMOSAT-7/COSMIC-2 indicates that the GNSS-R observed high S4 value is likely a sporadic E layer event.