AbstractAn established high‐resolution dynamical model is employed to understand the behavior of the thermosphere beneath the Earth's magnetic cusps, with emphasis on the factors contributing to the density structures observed by the CHAMP and Streak satellite missions. In contrast to previous modeling efforts, this approach combines first principles dynamical modeling with the high spatial resolution needed to describe accurately mesoscale features such as the cusp. The resulting density structure is shown to be consistent with observations, including regions of both enhanced and diminished neutral density along the satellite track. This agreement is shown to be the result of a straightforward application of input conditions commonly found in the cusp rather than exaggerated or extreme conditions. It is found that the magnitude of the density change is sensitive to the width of the cusp region and that models that can resolve widths on the order of 2° of latitude are required to predict density variations that are consistent with the observations.
