Atmospheric densities derived from CHAMP/STAR accelerometer observations

Bruinsma, Sean; Tamagnan, D.; Biancale, R.

doi:10.1016/j.pss.2003.11.004

Cited by 228 publications

(210 citation statements)

References 15 publications

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“…Such detailed evaluations can be performed only relatively recently thanks to the high-resolution total density data inferred from CHAMP (Bruinsma et al 2004), GRACE (Bruinsma & Forbes 2010), and GOCE accelerometer measurements, which have covered more than a solar cycle now. Still, these density datasets only allow fine analysis of the latitudinal structure on a per orbit (about 95 min) basis, and from pole to pole.…”

Section: Introductionmentioning

confidence: 99%

The DTM-2013 thermosphere model

Bruinsma¹

2015

J. Space Weather Space Clim.

146

100

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Aims -The Drag Temperature Model (DTM) is a semi-empirical model describing the temperature, density, and composition of the Earth's thermosphere. DTM2013 was developed in the framework of the Advanced Thermosphere Modelling and Orbit Prediction project (ATMOP). It is evaluated and compared with DTM2009, the pre-ATMOP benchmark, and the Committe on Space Research (COSPAR) reference model for atmospheric drag JB2008. Methods -The total density data used in this study, including the high-resolution CHAMP, GRACE and GOCE data, cover the 200-900 km altitude range and all solar activities. DTM2013 was constructed with the data assimilated in DTM2009, but with more GRACE data, and low-altitude GOCE data in particular. The solar activity proxy, F10.7 in DTM2009, has been replaced with F30. The bias and precision of the models is evaluated by comparing to the observations according to a metric, which consists of computing mean, RMS, and correlation. Secondly, the residuals are binned, which procedure aids in revealing specific model errors.Results -This evaluation shows that DTM2013 is the least biased and most precise model for the data that were assimilated.Comparison to independent density data shows that it is also the most accurate model overall. It is a significant improvement over DTM2009 under all conditions and at all altitudes, but the largest improvements are obtained at low altitude thanks to GOCE data. The precision of JB2008 decreases with altitude, which is due to its modeling of variations in local solar time and seasons in particular of the exospheric temperature rather than modeling these variations for the individual constituents.

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Section: Introductionmentioning

confidence: 99%

The DTM-2013 thermosphere model

Bruinsma¹

2015

J. Space Weather Space Clim.

146

100

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“…These densities are derived from changes in orbital velocity obtained from accelerometers. Such instruments have been flown on the Challenging Minisatellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE) satellites [Tapley et al, 2004;Bruinsma et al, 2004].…”

Section: Introductionmentioning

confidence: 99%

Predicting global average thermospheric temperature changes resulting from auroral heating

et al. 2011

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[1] The total Poynting flux flowing into both polar hemispheres as a function of time, computed with an empirical model, is compared with measurements of neutral densities in the thermosphere at two altitudes obtained from accelerometers on the CHAMP and GRACE satellites. The Jacchia-Bowman 2008 empirical thermospheric density model (JB2008) is used to facilitate the comparison. This model calculates a background level for the "global nighttime minimum exospheric temperature," T c , from solar indices. Corrections to this background level due to auroral heating, DT c , are presently computed from the Dst index. A proxy measurement of this temperature difference, DT c , is obtained by matching the CHAMP and GRACE density measurements with the JB2008 model. Through the use of a differential equation, the DT c correction can be predicted from IMF values. The resulting calculations correlate very well with the orbit-averaged measurements of DT c , and correlate better than the values derived from Dst. Results indicate that the thermosphere cools faster following time periods with greater ionospheric heating. The enhanced cooling is likely due to nitric oxide (NO) that is produced at a higher rate in proportion to the ionospheric heating, and this effect is simulated in the differential equations. As the DT c temperature correction from this model can be used as a direct substitute for the Dst-derived correction that is now used in JB200, it could be possible to predict DT c with greater accuracy and lead time.

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“…The measured acceleration, in absence of thrusts and after removal of angular accelerations and with Solar radiation pressure being negligible for altitudes below 150 km, is due to atmospheric drag. Details pertaining to the derivation of densities from accelerometer measurements were previously presented 22,23 . We processed the 8 Hz accelerometer data with the Geodesy by Simultaneous Numerical Integration (GINS) software which calculates satellite orbits by taking into account all gravitational and non-gravitational forces acting on the satellite 10 .…”

Section: Methodsmentioning

confidence: 99%

In situ observations of waves in Venus’s polar lower thermosphere with Venus Express aerobraking

et al. 2016

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Waves are ubiquitous phenomena found in oceans and atmospheres alike. From earliest formal studies of waves in the Earth's atmosphere to more recent studies on other planets, waves have been shown to play a key role in shaping atmospheric bulk structure, dynamics and variability [1][2][3][4] . Yet, waves are difficult to characterise as they ideally require in-situ measurements of atmosphere properties which are difficult to obtain away from Earth. Thereby, we have incomplete knowledge of atmospheric waves on planets other than our own, and we are thereby limited in our ability to understand and predict planetary atmospheres. We report on the first ever in-situ observations of atmospheric waves in Venus' thermosphere (130-140 km) at high latitudes (71.5-79.0 ). These were made by the Venus Express Atmospheric Drag Experiment (VExADE) 5 during aerobraking from June 24-July 11, 2014. As the spacecraft flew through Venus' atmosphere, deceleration by atmospheric drag was sufficient to obtain from accelerometer readings a total of 18 vertical density profiles. We infer an average temperature of T=114±23 K and findhorizontal wave-like density perturbations and mean temperatures being modulated at a quasi-5-day period.

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Atmospheric densities derived from CHAMP/STAR accelerometer observations

Cited by 228 publications

References 15 publications

The DTM-2013 thermosphere model

The DTM-2013 thermosphere model

Predicting global average thermospheric temperature changes resulting from auroral heating

In situ observations of waves in Venus’s polar lower thermosphere with Venus Express aerobraking

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