Calibration of GRACE on-board accelerometers for thermosphere density derivation

ABSTRACT

Low Earth Orbit satellite on-board accelerometers play an important role in improving our understanding of thermosphere density; however, the accelerometer-derived densities are subject to accelerometer calibration errors. In this study, two different dynamic calibration schemes, the accelerometer parameter-incorporated orbit fitting and precise orbit determination (POD), are investigated with the Gravity Recovery And Climate Experiment (GRACE) satellite accelerometers for thermosphere density derivation during years 2004–2007 (inclusive). We show that the GRACE accelerometer parametrization can be optimized by fixing scale coefficients and estimating biases every 60 min so that the orbit fitting and POD precision can be improved from 10 cm to 2 cm in the absence of empirical acceleration compensations and as a result the integrity of calibration parameters may be reserved. The orbit-fitting scheme demonstrates similar calibration precision with respect to POD. Their bias estimates in the along-track and cross-track components exhibit an offset within 0.1% and a standard deviation (STD) less than 0.3%. Correspondingly, a bias of 2.20% and a STD of 5.75% exists between their thermosphere density estimates. The orbit-fitting and POD-derived thermosphere densities are validated through the comparison against the results published by other institution. The comparison shows that either of them can achieve a precision level at 6%. To derive thermosphere density from the rapid-increasing amount of on-board accelerometer data sets, it is suggested to take full advantage of the orbit-fitting scheme due to its high efficiency as well as high precision.

KEYWORDS:

• GRACE accelerometer calibration
• thermosphere density
• precise orbit determination
• orbit fit

Acknowledgments

We would like to acknowledge the ISDC for providing the GRACE data, JPL for providing the JPL precision products, and Dr. Doornbos for providing the GRACE density products.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

All data included in this research are available upon request by contacting with the corresponding author by [email protected].

Additional information

Funding

This research is sponsored by the National Natural Science Foundation [grant numbers 42004020, 42074032, 41931075 and 42030109]; National Defense Key Laboratory of Aerospace Flight Dynamics technology (grant number 6142210190101); China Postdoctoral Science Foundation [grant number 2021M692460]; the Fundamental Research Funds for the Central Universities [grant number 2042021kf0060]; and Wuhan Science and Technology Bureau [grant number 2019010701011391].

Notes on contributors

Min Li

Min Li is a professor in GNSS Research Center, Wuhan University. He received the B.S. and Ph.D. degrees in geodesy and surveying engineering from Wuhan University in 2005 and 2011, respectively. His research interests include GNSS/LEO satellite precise orbit determination as well as multi-GNSS processing using GPS, GLONASS, BeiDou, and Galileo.

Zhuo Lei

Zhuo Lei is currently a master candidate at the Wuhan University. She has completed her B.Sc. at the College of Geology Engineering and Geomatics, Chang’an University, in 2019. Her area of research currently focuses on the GNSS data processing.

Wenwen Li

Wenwen Li is a research assistant in GNSS Research Center, Wuhan University. He received his B.S., M.S., and Ph.D. degrees from Wuhan University in 2012, 2015, and 2019, respectively. His current research focuses on LEO-based GNSS data precise processing and its application in atmosphere studies including thermosphere and ionosphere inversion.

Kecai Jiang

Kecai Jiang received the B.S. degree in geomatics engineering from Central South University in 2013, and the Ph.D. degree in geodesy and surveying engineering from Wuhan University in 2020. He is currently a Postdoctoral Researcher with Wuhan University. His current research mainly focuses on LEO orbit determination using GNSS.

Youcun Wang

Youcun Wang received the M.S. degree in geomatics engineering from the Shandong University of Science and Technology in 2019. He is currently working toward the doctoral degree in geodesy and surveying engineering at Wuhan University. His main research interests include the precision orbit determination of LEO and dynamics model refinement.

Qile Zhao

Qile Zhao is a professor in GNSS Research Center, Wuhan University. He received the Ph.D. degree in geodesy and surveying engineering from Wuhan University in 2004. His current research interests are precise orbit determination of GNSS and LEO satellites, and high-precision positioning using GPS, Galileo, and BeiDou system.