Ionospheric Scintillation Monitoring With ROTI From Geodetic Receiver: Limitations and Performance Evaluation

Abstract

AbstractBy comparing amplitude scintillation index S4 from scintillation receivers and Rate of change of Total electron content Index (ROTI) from nearby geodetic receivers in low latitude region of China during year 2015, this work summarized the limitations of ROTI in indicating ionospheric scintillation and quantitatively evaluated the performance/reliability of ROTI in monitoring ionospheric scintillation in low latitude region. The results indicate that the correlation between ROTI and S4 is lower (higher) when scintillation occurs at lower (higher) satellite elevation angle. Erroneous cycle slips and longer ROTI calculation time interval degrade the integrity of ROTI calculated from 30‐s sampling interval data (abbreviated as 30s‐ROTI). ROTI calculated from 1‐s sampling interval data (abbreviated as 1s‐ROTI) has better integrity (90%) than that of 30s‐ROTI (60%). In addition, we propose a reasonable threshold of 0.25 m for cycle slip detection for the 30‐s cadence observation data to avoid misjudging a large ionospheric variation as a cycle slip and further improve on the integrity of 30s‐ROTI. The deviation of ROTI from S4 decreases the reliability of ROTI in indicating the occurrence of ionospheric scintillation as well as the correlation between ROTI and S4. The reliability of ROTI in indicating the occurrence of scintillation can reach 80% and 88% for 30s ROTI and 1s‐ROTI, respectively. The deviation causes 60% of the correlations between 30s‐ROTI and S4 drop by 0.15 ∼ 0.2 and causes more than 66% of the correlations between 1s‐ROTI and S4 drop by 0.15 ∼ 0.2. These results establish an important reference concerning the reliability of ROTI in indicating the occurrence of ionospheric scintillation.