Journal cover Journal topic
Annales Geophysicae Sun, Earth, planets, and planetary systems An interactive open-access journal of the European Geosciences Union
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Regular paper
06 Apr 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Annales Geophysicae (ANGEO).
An empirical model (CH-Therm-2018) of the thermospheric mass density derived from CHAMP
Chao Xiong1, Hermann Lühr1, Michael Schmidt2, Mathis Bloßfeld2, and Sergei Rudenko2 1GFZ German Research Centre for Geosciences, Telegrafenberg,14473 Potsdam, Germany
2Deutsches Geodätisches Forschungsinstitut at the Technische Universität München (DGFI-TUM), Arcisstr. 21, 80333 Munich, Germany
Abstract. Thermospheric drag is the major non-gravitational perturbation acting on Low Earth Orbit (LEO) satellites at altitudes up to 1000 km. The drag depends on the thermospheric density, which is a key parameter in the planning of LEO missions, e.g. their lifetime, collision avoidance, precise orbit determination, as well as orbit and re-entry prediction. In this study, we present an empirical model, named CH-Therm-2018, of the thermospheric mass density derived from 9-year (from August 2000 to July 2009) accelerometer measurements at altitude from 460 to 310 km, from the CHAllenging Minisatellite Payload (CHAMP) satellite. The CHAMP dataset is divided into two 5-year periods with 1-year overlap (from August 2000 to July 2005 and from August 2004 to July 2009), to represent the high-to-moderate and moderate-to-low solar activity conditions, respectively. The CH-Therm-2018 model is a function of seven key parameters, including the height, solar flux index, season (day of year), magnetic local time, geographic latitude and longitude, as well as magnetic activity represented by the solar wind merging electric field. Predictions of the CH-Therm-2018 model agree well with the CHAMP observations (disagreements within ±20 %), and show different features of thermospheric mass density during solar activities, e.g. the March-September equinox asymmetry and the longitudinal wave pattern. We compare the CH-Therm-2018 predictions with the Naval Research Laboratory Mass Spectrometer Incoherent Scatter Radar Extended (NRLMSISE-00) model. The result shows that CH-Therm-2018 better predicts the density evolution during the last solar minimum (2008-2009) than the NRLMSISE-00 model. By comparing the Satellite Laser Ranging (SLR) observations of the ANDE-Pollux satellites during August-September 2009, we estimate 6-h scaling factors of thermospheric mass density and obtain a median value of 1.27 ± 0.60, indicating that our model, on average, slightly underestimates the thermospheric mass density at solar minimum.
Citation: Xiong, C., Lühr, H., Schmidt, M., Bloßfeld, M., and Rudenko, S.: An empirical model (CH-Therm-2018) of the thermospheric mass density derived from CHAMP, Ann. Geophys. Discuss.,, in review, 2018.
Chao Xiong et al.
Chao Xiong et al.
Chao Xiong et al.


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