Comprehensive particle and field observations of magnetic storms at different local times from the CRRES spacecraft

The response of ring current intensification to three magnetic storms sampled at dawn, midnight, and dusk is investigated. We use a comprehensive set of data from the CRRES satellite, using plasma, energetic particle (ion composition), electric field, and magnetic field data, which is ideal for investigating the interrelationship between the ring current strength as measured by D_st, the particle (current carriers) in the outer radiation belt, their effects on the global magnetic field, and the convection effects caused by large dawn-dusk electric fields. This yields a comprehensive and self-consistent picture of storm time radiation belt formation based entirely on data. At all local times investigated strong, stretching (flattening) of the magnetic field down to L < 4 is observed during the storm main phase, showing that this field line stretching is not limited to midnight. Ring current ions above 100 keV are shown to form a partial ring current during the main phase as they are only sampled at dawn during the recovery phase when the electric field vanishes. Comparing this feature to Kp-dependent models of the proton Alfvén layer shows that dawn is only accessible to these ions after the main phase. Ionospheric origin ions (O⁺) follow dynamics very similar to those of H⁺, indicating a source in the plasma sheet. Solar wind ions (He⁺⁺) are controlled by their solar wind source and have immediate access during the main phase. He⁺, which is generated in the ionosphere as well as by charge exchange, has behavior similar to that of O⁺ and H⁺. In contrast to the current view, plasma sheet ions in the energy range from 5 to 28 keV contribute significantly in the energy density of the ring current during the storm main phase.