Sensing Thermospheric Density Using COSMIC-2 Satellite GNSS Data

Jian Yao, Jan-Peter Weiss, Tzu-Wei Fang, Eric Sutton, and Tim Fuller-Rowell

Abstract: A low-Earth orbit (LEO) satellite typically has an altitude of a few hundred kilometers, residing in the thermosphere. The UCAR COSMIC Program helps operate and manage the six-satellite COSMIC-2 constellation, a US-Taiwan partnership led by NOAA and the Taiwan Space Agency, which aims at GNSS radio occultation applications. In this paper we report a new application of COSMIC-2 satellite data for sensing thermospheric density. Thanks to advanced onboard GNSS receivers, we can compute the COSMIC-2 satellite orbits at a precision of around 8 cm (3D). As part of the precise-orbit-determination (POD) processing, we estimate the along-track acceleration every five minutes. After analyzing one month of daily-averaged along-track acceleration data of COSMIC-2 satellites, we find a similar pattern to the modeled thermospheric density, which verifies the feasibility of sensing thermospheric density using COSMIC-2. To improve the temporal (and thus spatial) resolution of thermospheric density, a major challenge is to de-couple the drag acceleration due to thermosphere from the solar radiation pressure (SRP) acceleration. By incorporating the satellite layout as well as the epoch-to-epoch attitude information, we can model the SRP acceleration and achieve a 5-min resolution of thermospheric-density sensing. This thermospheric density product can contribute to thermosphere monitoring, space weather forecast, modeling of the atmosphere, and orbit prediction for satellite collision avoidance.
Published in: Proceedings of the 36th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2023)
September 11 - 15, 2023
Hyatt Regency Denver
Denver, Colorado
Pages: 3217 - 3226
Cite this article: Yao, Jian, Weiss, Jan-Peter, Fang, Tzu-Wei, Sutton, Eric, Fuller-Rowell, Tim, "Sensing Thermospheric Density Using COSMIC-2 Satellite GNSS Data," Proceedings of the 36th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2023), Denver, Colorado, September 2023, pp. 3217-3226. https://doi.org/10.33012/2023.19259
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