A Novel Index for Equatorial Spread F Detection in Low Latitudes Using COSMIC Radio Occultation Data

Abstract Simulating ionospheric conditions, including their temporal and spatial variability, and predicting irregularities remain critical challenges for mitigating space weather effects, especially in low‐latitude regions. This paper introduces the Radio Occultation Rate of Change of Electron Density Index (RORCED), a novel altitude‐resolved index to detect Equatorial Spread F events. We leveraged Electron Density Profiles (EDPs) derived from the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) Radio Occultation (RO) data. The method was validated using ionosonde data from Ilorin (Geographic: ; Geomagnetic: ) and Fortaleza (Geographic: 3.90°S, 38.4°W; Geomagnetic: 11.4°S) stations in the low‐latitude region. COSMIC RO data were analyzed when the maximum height of the F2 layer (hmF2) fell within a latitudes/longitudes spatial resolution. These locations were chosen for their data availability, which was used for validation. We used geomagnetically quiet‐time EDPs and established a detection threshold of cm −3 /km. The validation achieved an accuracy of 82% out of 1,330 samples. We compared the RORCED with the Rate of Change of Density Index (RODI) from Swarm satellites and the Rate of Change of Total Electron Content Index (ROTI) from GNSS observations over both low and equatorial regions. The comparisons demonstrated consistent plasma irregularity detection patterns, aligning with established methods. The method can also be applied to develop modeling and forecasting approaches in regions lacking ground‐based instrumentation, offering transformative potential for both scientific research and operational applications.