Study of ionospheric scintillations in low-latitude regions using multi-sensor data

Abstract

GNSS radio occultation (RO) observations conducted on board low-earth orbit (LEO) satellites are widely used in many atmospheric applications, including ionospheric and space weather research. Utilizing information from four satellites/missions, we have employed a multi-satellite, multi-instrument strategy to detect ionospheric irregularities causing scintillations over the low-latitude equatorial region. We used the electron density (Ne) and total electron content (TEC) profiles from COSMIC-2, as well as high rate 50 Hz atmospheric phase (conPhs) with signal to noise ratio (SNR) measurements along GNSS-RO ray-path obtained by STRATOS reciever onboard Spire's CubeSats constellation. Equatorial plasma bubbles in the post-sunset sector are identified using the nighttime disk images from the Global-scale Observations of the Limb and Disk (GOLD) mission. We also took advantage of the availability of the Ion Velocity Meter (IVM) instrument from Ionospheric Connections Explorer (ICON), which provides electron density in-situ data. The GNSS-RO high rate conPhs files from Spire and the COSMIC-2 ionPrfs are accessed via the University Corporation for Atmospheric Research (UCAR) data repository. The onboard amplitude scintillation detection method in Spire CubeSats allows continuous recording of 50 Hz phase and pseudorange data up to satellite orbit height, and such data are levelled as "extended profiles". At present, this functionality is restricted only to the GPS constellation. Amplitude scintillation index S4 derived from the 50 Hz SNR data of the extended profiles, is used to detect the F-layer amplitude scintillations. We applied an irregularity detection technique to the TEC and COSMIC-2 Ne profiles, which reach altitudes in the F-layer as well. We have additionally detected irregularity events after sunset using the ICON in-situ electron density data. The equatorial plasma bubbles seen in the GOLD images, and in the COSMIC-2 and ICON observations are closely related in both space and time. Our study shows that the GNSS-RO data from commercial CubeSats can be used in concert with other satellite missions, such as GOLD data, to enhance and augment ionospheric scintillation research conducted by COSMIC-2 and other RO missions.