Ionospheric scintillation observations – a multi-sensor approach over low-latitude equatorial region

Abstract

Many atmospheric applications, such as ionospheric and space weather investigations, frequently use GNSS radio occultation (RO) observations carried out onboard low-earth orbit (LEO) satellites. To detect ionospheric irregularities causing scintillations across the low latitude equatorial region, we have used a multi-sensor, multi-instrument approach consisting of data from four satellites/missions. For GNSS-RO data, we used high rate 50 Hz atmospheric phase (conPhs) with signal to noise ratio (SNR) measurements recorded by STRATOS onboard Spire's CubeSats constellation and the electron density (Ne) and total electron content (TEC) profiles from COSMIC-2. The nighttime disk scans from Global-scale Observations of the Limb and Disk (GOLD) mission are used to identify equatorial plasma bubbles in the post sunset sector. We also used the in-situ electron density measurements from Ionospheric Connections Explorer’s (ICON) Ion Velocity Meter (IVM) instrument. For this work, the University Corporation for Atmospheric Research (UCAR) data repository is used to access the COSMIC-2 ionPrfs and Spire's GNSS-RO high rate conPhs files. The onboard amplitude scintillation detection algorithm in Spire CubeSats enable the continuous recording of 50 Hz phase and pseudorange data up to satellite orbit height, referred to as ‘an extended profile’. This capability is only restricted to the GPS constellation. Owing to such extended profiles, F-layer amplitude scintillations events are detected by computing the S4 index from the 50 Hz SNR data. We implemented an irregularity detection algorithm to the COSMIC-2 Ne and TEC profiles, which also extend up to F-layer altitudes. Using the ICON in-situ electron density measurements, we also identified irregularity events post-sunset. These observations are in close spatial and temporal proximity with the equatorial plasma bubbles observed from the GOLD images. The results of this study demonstrate how GNSS-RO data from commercial CubeSats can be used to supplement and improve ionospheric scintillation research carried out by COSMIC-2 and other RO missions, in conjunction with other satellite missions, like GOLD.