Revealing Inconsistencies in ROTI Index Using Multi‐GNSS Constellation Measurements: Impact of Sampling Rates and Time Window.

Understanding ionospheric irregularities and their dynamics is crucial, with the rate of change of the total electron content index (ROTI) serving as a significant metric for this purpose. However, inconsistencies in ROTI magnitudes have been noted when sampled at one‐second interval across various Global Navigation Satellite System (GNSS) receivers. This study presents a detailed statistical analysis to investigate inconsistencies in ROTI using multi‐GNSS observations in conjunction with four distinct GNSS receiver types. Various factors affecting the ROTI inconsistencies among receivers were examined, including differences in sampling rates (1, 5, 15, and 30 s), and varying time window widths (1, 2, and 5 min). By examination of data obtained from GNSS receivers with zero or short baselines on a global scale, the analysis uncovered substantial variations in multi‐GNSS ROTI values across the four assessed receiver types. The main findings suggest that reducing the sampling rate reduces the inconsistencies in the magnitude of ROTI, particularly at lower sampling rates. This reduction can be attributed to the exclusion of high‐frequency components in the ROTI spectrum. Interestingly, the width of the time window is found to have minimal impact on the ROTI magnitude. The study also shows a direct correlation between a larger magnitude of ROTI and the increased noise in the signals tracked by receivers. These results emphasize the importance of considering sampling rates and GNSS receiver types when utilizing ROTI to investigate ionospheric irregularities. Plain Language Summary: Studying the changes in the ionosphere is important, and the rate of change of total electron content index (ROTI) is a key measure used for this purpose. ROTI is calculated using data from Global Navigation Satellite Systems (GNSS). However, variations in ROTI values were seen when measured at one‐second interval using different types of GNSS receivers. This study looked at these variations by analyzing ROTI data from multiple GNSS systems (BeiDou, GPS, GLONASS, and Galileo) and different types of GNSS receivers (Septentrio, Javad, Trimble, and Leica). Factors like sampling rates (1, 5, 15, and 30 s) and time window widths (1, 2, and 5 min) were considered during the analysis. The research found notable differences in multi‐GNSS ROTI values among the receiver types, with the Septentrio and Trimble receiver showing the most significant variations. Lowering the sampling rate led to fewer inconsistencies at slower rates, which is caused by a decrease in the multi‐GNSS ROTI values due to missing high‐frequency components. It was interesting to discover that the duration of the time window had little impact on ROTI values. These results stress the importance of paying attention to sampling rates and the type of GNSS receiver when using ROTI to study ionospheric irregularities. Key Points: Differences in multi‐GNSS ROTI values were observed across various receiver types at zero/short‐baseline stations globallyLowering the sampling rate decreased inconsistencies in the multi‐GNSS ROTI values among diverse receiversTime window width had a minimal impact on both the consistency and magnitude of multi‐GNSS ROTI values [ABSTRACT FROM AUTHOR]