Space Weather Modeling Capabilities Assessment: Neutral Density and Orbit Determination at LEO

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Monday, February 25, 2019

The specification and prediction of density changes in the thermosphere is a key challenge for space weather observations and modeling, because it is one result of complex interactions between the Sun and the terrestrial atmosphere, and also because it is of operational importance for tracking objects orbiting in near-Earth space.

Graph depicting TIE-GCM density ratios computed with 2007 CHAMP data
TIE-GCM density ratios computed with 2007 CHAMP data (black: 24hr moving average).

For low-Earth orbit, neutral density variation is the most important uncertainty for propagation and prediction of orbital elements. A recent international conference conducted under the auspices of the NASA Community Coordinated Modeling Center included a workshop on neutral density modeling, using both empirical and numerical methods, and resulted in organization of an initial effort in model comparison and evaluation. Here, we report on the exploitable density datasets available, the selected years and storm events, and the metrics for complete model assessment.

Comparisons between five models (three empirical and two numerical) and neutral density data sets that include measurements by the CHAMP, GRACE, and GOCE satellites are presented as examples of the to be implemented assessment procedure. The models in general performed reasonably well, although seasonal errors sometimes are present, and impulsive geomagnetic storm events remain challenging. Numerical models are still catching up to empirical methods on a statistical basis, but hold great potential for describing these short-term variations.

Publication Name: Space Weather

First HAO Author's Name: Stanley C. Solomon

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