Joint Analysis of Spatial Ionospheric Gradients and Scintillation Fading Coefficients

Abstract The availability and integrity of Global Navigation Satellite Systems (GNSS) signals in low‐latitude areas are seriously threatened by ionospheric irregularities which lead to amplitude scintillation. To better understand the low‐latitude ionospheric impact on GNSS signal this study examines the relation between severe spatial ionospheric gradients, amplitude scintillation (quantified by the S 4 index), and the fading coefficients of the α ‐ μ model. Severe ionospheric gradients are typically observed in association with S 4 greater than 0.6. These values of S 4 , however, are not sufficient to be associated to the occurrence of severe gradients. For GNSS‐based systems, severe gradients create vulnerability scenarios by inducing integrity problems. The results in this work indicate that, given a fixed S 4 , the values of the fading coefficient α increase with gradient severity, suggesting a greater likelihood of deep signal fading. This correspondence is important because under larger S 4 and α , the average time between cycle slips in the receiver is expected to decrease significantly, compromising the signal availability. The results also suggest that, to improve GNSS resilience, an integrated evaluation of S 4 , α , and ionospheric gradients must be considered in the development of more effective mitigation measures. For safety‐critical GNSS applications, future studies should concentrate on improving these statistical models and incorporating them into operational monitoring frameworks.