The pre-ATMOP DTM models

The Drag Temperature Model (DTM) is a semi empirical model describing the temperature, density and composition of the Earth's thermosphere.

Its first version DTM-78 (Barlier et al., 1978) used direct measurements of exospheric temperature and atmospheric densities derived from satellite drag data. It has been officially upgraded twice: DTM-94 (Berger et al., 1998) and DTM-2000 (Bruinsma et al., 2003). DTM-2000 was the first model to have been constructed not with the usual solar activity proxy F10.7, but with the MgII index converted to F10.7 units (sfu). These models are mainly used in orbit determination software.

The model is maintained and developed by CNES. The latest pre-ATMOP version of DTM is DTM-2009 (Bruinsma et al., 2012), which was the only model to have assimilated high-accuracy and high-resolution densities inferred from accelerometers onboard CHAMP (Bruinsma et al., 2004) and GRACE. This model is the starting point of the new developments in the framework of the “Advanced Thermosphere Model for Orbit Prediction (ATMOP)” research project.

The DTM-2012 model

DTM-2012 is the first of two models that are developed within the ATMOP project. The objective is to improve the model in two stages, first by replacing the solar activity proxy index F10.7 with a more representative index of chromospheric activity, such as MgII, or directly with measurements of the HeII line in the solar EUV band. The second and final ATMOP model will be released in the fall of 2013, and at that time a new geomagnetic index, which is currently being elaborated within ATMOP, will be used instead of the 3-hourly planetary geomagnetic index am. 

A study by Dudok de Wit and Bruinsma (2011) showed that the best modeling results are obtained with HeII measurements from SOHO/SEM on all time scales (i.e. smaller and larger than a solar rotation). Therefore, two versions of DTM-2012 were constructed under identical conditions except for the solar activity indices used, either F10.7 or S10.7 (SOHO/SEM converted to F10.7 units).

Initially the F10.7 model was simply constructed for reference purposes in order to quantify the gain in accuracy entirely due to the solar activity index, but after full evaluation of both models it was decided to select the F10.7 model as the new DTM-2012. In short, there is a problem in the slowly evolving component of HeII/S10.7 when using the complete SOHO time series starting in 1996. Dudok de Wit and Bruinsma (2011) did not detect the problem in part because they analyzed a shorter time span. 

The model evaluation is given in the Evaluation Report (evaluation report and density maps), which shows comparisons to data for DTM2012, as well as the a-priori model DTM-2009, and the COSPAR reference models JB2008 and NRLMSISE-00.

DTM-2012 can be downloaded, after registering.

The DTM-2013 model

DTM-2013 implements several improvements with respect to DTM-2012. The most relevant are:

- GOCE data at 270 km altitude have been used, and the low-altitude accuracy of the model is significantly higher as a result

- The F30 (30 cm radio flux) proxy is used instead of F10.7, and this also leads to a significant improvement

The model evaluation is given in the Evaluation Report (evaluation report)

DTM-2013 can be downloaded, after registering.

Downloading and installing

DTM models are available for download for registed users.

Installation instructions and benchmark values are equally provided. 

For questions please contact Sean Bruinsma (sean.bruinsmaATcnes.fr).

 

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References



Barlier, F., Berger, C., Falin, J.L., Kockarts, G., Thuillier, G., 1978. A thermospheric model based on satellite drag data, Ann. Geophys, 34, 9-24.

Berger, C., Biancale, R., Ill, M., Barlier, F., 1998. Improvement of the empirical thermospheric model DTM: DTM-94- comparative review on various temporal variations and prospects in space geodesy applications, J of Geod., 72, 161- 178.

Bruinsma, S.L., Thuillier, G., Barlier, F., 2003. The DTM-2000 empirical thermosphere model with new data assimilation and constraints at lower boundary : accuracy and properties, J of Atmospheric and Solar-Terrestrial Physics, 65, 1053-1070.

Bruinsma, S.L., Tamagnan, D., Biancale, R., 2004. Atmospheric densities derived from CHAMP/STAR accelerometer observations, Plan. Space Sci., 52, 297-312.

Bruinsma, S.L., Sánchez-Ortiz, N., Olmedo, E., Guijarro, N. (2012) Evaluation of the DTM-2009 thermosphere model for benchmarking purposes, J. Space Weather Space Clim.

Dudok de Wit, T., S. Bruinsma (2011) Determination of the most pertinent EUV proxy for use in thermosphere modeling, Geophys. Res. Lett., doi:10.1029/2011GL049028


ATMOP project has received EC research funding (Grant Agreement Number 261948)

EC is not liable for any use of the information provided in the documents provided on the ATMOP project websites


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