Ionospheric irregularity signatures observed in grazing-angle GNSS-R measurements

In this study, we investigate ionospheric irregularity signatures captured in Spire’s grazing-angle GNSS reflectometry (GNSS-R) measurements during the November 2023 geomagnetic storm. GNSS signals reflected at grazing angles provide a potential opportunity to monitor ionospheric variability over polar regions, where conventional observations remain sparse. A key challenge in interpreting reflected GNSS signals is distinguishing ionospheric impacts from surface-related effects. During this November storm period, the Arctic region exhibited extended areas of coherent reflection under wintertime polar conditions. These conditions are favorable for reducing surface-related effects and enhancing sensitivity to ionospheric signatures. Preliminary results indicate enhanced Total Electron Content (TEC) fluctuation activity, represented by the Rate of TEC Index (ROTI), in reflected signals within coherent reflection regions during periods of elevated ionospheric disturbance. These results suggest that grazing-angle GNSS-R observations over coherent regions have strong potential for observing ionospheric irregularities and may provide complementary information for monitoring high-latitude plasma disturbances. To further evaluate the reliability of the reflected-signal signatures, we will compare the GNSS-R observations with independent collocated measurements from other ionospheric monitoring instruments for cross-validation and characterization of the irregularity environment.