A Comparison of Sporadic-E Occurrence Rates Using GPS Radio Occultation and Ionosonde Measurements

Authors

Rodney Carmona, Space Vehicles Directorate, Air Force Research Laboratory
Omar A. Nava, Air Force Institute of Technology
Eugene V. Dao, Space Vehicles Directorate, Air Force Research Laboratory
Daniel J. Emmons, Air Force Institute of Technology

Document Type

Article

Publication Date

1-26-2022

Abstract

Sporadic-E (E_s) occurrence rates from Global Position Satellite radio occultation (GPS-RO) measurements have shown to vary by a factor of five between studies, motivating the need for a comparison with ground-based measurements. In an attempt to find accurate GPS-RO techniques for detecting E_s formation, occurrence rates derived using five previously developed GPS-RO techniques are compared to ionosonde measurements over an eight-year period from 2010–2017. GPS-RO measurements within 170 km of a ionosonde site are used to calculate E_s occurrence rates and compared to the ground-truth ionosonde measurements. The techniques are compared individually for each ionosonde site and then combined to determine the most accurate GPS-RO technique for two thresholds on sporadic-E intensity: no lower limit and fbEs ≥3 MHz. Overall, the YuS₄ method shows the closest agreement with ionosonde measurements for total E_s occurrence rates without a lower limit on intensity, while the phase-based Chu technique shows the closest agreement for fbEs ≥3 MHz. This analysis demonstrates that the variation in GPS-RO derived sporadic-E occurrence rates is due to varying thresholds on the sporadic-E intensities in terms of fbEs.

Comments

Copyright statement: © 2022 by the Authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY 4.0) license (https:// creativecommons.org/licenses/by/ 4.0/).

Associated data objects: GNSS and Digisonde sporadic-E maps produced by Air Force Institute of Technology. https://zenodo.org/records/6977022 (Version 1 available under Additional Files below.)

Funding note: This research was funded by the Air Force Office of Scientific Research (AFOSR/RTB1).

DOI

10.3390/rs14030581

Source Publication

Remote Sensing

Recommended Citation

Carmona, R. A., Nava, O. A., Dao, E. V., & Emmons, D. J. (2022). A Comparison of Sporadic-E Occurrence Rates Using GPS Radio Occultation and Ionosonde Measurements. Remote Sensing, 14(3), 581. https://doi.org/10.3390/rs14030581