Abstract
Abstract. 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 from the CHAllenging Mini-satellite Payload (CHAMP) satellite at altitudes from 460 to 310 km. 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 describes the thermospheric density as a function of seven key parameters, namely 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 CHAMP observations (within 20 %) and show different features of thermospheric mass density during the two solar activity levels, e.g., the March–September equinox asymmetry and the longitudinal wave pattern. From the analysis of satellite laser ranging (SLR) observations of the ANDE-Pollux satellite during August–September 2009, we estimate 6 h scaling factors of the thermospheric mass density provided by our model and obtain the median value equal to 1.267±0.60. Subsequently, we scale up our CH-Therm-2018 mass density predictions by a scale factor of 1.267. We further compare the CH-Therm-2018 predictions with the Naval Research Laboratory Mass Spectrometer Incoherent Scatter Radar Extended (NRLMSISE-00) model. The result shows that our model better predicts the density evolution during the last solar minimum (2008–2009) than the NRLMSISE-00 model.
Highlights
The thermosphere is the top layer of the gravitationally bound part of the atmosphere, which is partly ionized and extends from about 90 to over 600 km (Lühr et al, 2004)
We present an empirical model, named CH-Therm-2018, of the thermospheric mass density derived from 9-year accelerometer measurements from the CHAllenging Minisatellite Payload (CHAMP) satellite at altitudes from 460 to 310 km
The CH-Therm-2018 model describes the thermospheric density as a function of seven key parameters, namely the height, solar flux index, season, magnetic local time, geographic latitude and longitude, as well as magnetic activity represented by the solar wind merging electric field
Summary
The thermosphere is the top layer of the gravitationally bound part of the atmosphere, which is partly ionized and extends from about 90 to over 600 km (Lühr et al, 2004). Liu et al (2013) and Yamazaki et al (2015) reported two empirical models derived from recent LEO missions, such as the CHAllenging Minisatellite Payload (CHAMP, Reigber et al, 2002) and the Gravity Recovery and Climate Experiment (GRACE, Tapley et al, 2004) These two models represent well the prominent thermospheric structures at low latitudes like the equatorial mass density anomaly (EMA) and the wave-4 longitudinal pattern, as well as the solar wind influence on the high-latitude thermosphere, respectively. Different to Liu et al (2013) and Yamazaki et al (2015), we take into account in this study the dataset from August 2000 to July 2009 for constructing our empirical models of the thermospheric mass density, to make more efficient use of the CHAMP observation This period includes high and low solar activities and the CHAMP satellite altitude.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
