A comparison of the effects of CIR- and CME-induced geomagnetic activity on thermospheric densities and spacecraft orbits: Case studies

Thus, the satellite orbit decay rates during CME-storms are usually larger than those during CIR-storms. However, CIR-storms often had long durations that perturbed satellite orbits for longer periods of time. As a result, the total thermospheric density changes and satellite orbit decays for the entire periods of CIR-storms were much greater than those for the CME-storms since these parameters were related to the total energy deposited into the thermosphere/ionosphere, which depended on both the strengths and the durations of the storms.

This study indicates that more attention should be paid to CIR storms during the declining phase and during solar minimum, when they occur frequently and periodically. Whereas fewer CME storms occurring under these conditions. We also found that changes in thermospheric densities and CHAMP orbit decay rates correlated well with variations of auroral hemispheric power, but lagging by about 3-6 h.