The First Atmospheric Radio Occultation Profiles From a GPS Receiver in Geostationary Orbit

This letter will present the first radio occultation (RO) electron density profiles of Earth's atmosphere generated from a global positioning system (GPS) receiver in a geostationary orbit. The GPS receivers on the geostationary operational environmental satellites (GOES)-16 (R) and GOES-17 (S) satellites track GPS signals propagated through the Earth's atmosphere and can be used to estimate electron density profiles. RO profiles from geosynchronous orbit hold the potential to generate unique temporal and spatial atmospheric measurements complementary to those from the ground and low Earth orbit (LEO) space-based receivers, including limb observations of the upper atmosphere at altitudes above traditional low Earth-orbiting RO satellites. This letter will present details of the GOES satellite GPS receivers and the limitations and challenges in generating RO profiles with its current hardware and software configuration. Following, the temporal and geospatial coverage for each of the GOES satellites will be presented, quantifying the frequency and number of GPS signals tracked down to sufficiently low enough altitudes to provide useful atmospheric information. Next, the data processing required to generate excess phase and electron density profiles will be described and demonstrated using two examples of GOES profiles. Subsequently, these two example GOES RO profiles will be compared to and calibrated with an ionospheric model, compared with co-located profiles from the LEO constellation observing system for meteorology ionosphere and climate-2 (COSMIC-2) constellation and a ground-based ionosonde.