Frontiers in Astronomy and Space Sciences (Dec 2023)

Improved models for estimating sporadic-E intensity from GNSS radio occultation measurements

  • Daniel J. Emmons,
  • Dong L. Wu,
  • Nimalan Swarnalingam,
  • Nimalan Swarnalingam,
  • Ashar F. Ali,
  • Joseph A. Ellis,
  • Kyle E. Fitch,
  • Kenneth S. Obenberger

DOI
https://doi.org/10.3389/fspas.2023.1327979
Journal volume & issue
Vol. 10

Abstract

Read online

Several models for estimating sporadic-E intensity from Global Navigation Satellite System (GNSS) radio occultation (RO) observation have previously been developed using a single perturbation or intensity parameter, such as phase-based total electron content (TEC) or the amplitude-based S4 index. Here, we outline two new models that use a combination of phase and amplitude parameters for the L1 and L2 signals. These models show a significant improvement over the baseline models used for comparison. Furthermore, the GNSS-RO parameters are compared with several different ionosonde intensity parameters including the direct foEs and fbEs measurements along with the metallic-ion based foμEs and fbμEs parameters which account for the background E-region density. Interestingly, the phase-based σϕ scintillation index shows the strongest correlation to foEs and fbEs while amplitude-based S4 shows the strongest correlation to foμEs and fbμEs. While the metallic-ion based foμEs and fbμEs parameters are physically ideal for GNSS-RO observations, we show difficulties in practical implementation due to the reliance on a background E-region density estimate using a model such as the International Reference Ionosphere (IRI). Ultimately, we provide two improved sporadic-E intensity models that can be used for future GNSS-RO based studies along with a recommendation to compare against the ionosonde-based foEs parameter.

Keywords