[1] Twenty one differences between CME-driven geomagnetic storms and CIR-driven geomagnetic storms are tabulated. (CME-driven includes driving by CME sheaths, by magnetic clouds, and by ejecta; CIR-driven includes driving by the associated recurring high-speed streams.) These differences involve the bow shock, the magnetosheath, the radiation belts, the ring current, the aurora, the Earth's plasma sheet, magnetospheric convection, ULF pulsations, spacecraft charging in the magnetosphere, and the saturation of the polar cap potential. CME-driven storms are brief, have denser plasma sheets, have strong ring currents and Dst, have solar energetic particle events, and can produce great auroras and dangerous geomagnetically induced currents; CIR-driven storms are of longer duration, have hotter plasmas and stronger spacecraft charging, and produce high fluxes of relativistic electrons. Further, the magnetosphere is more likely to be preconditioned with dense plasmas prior to CIR-driven storms than it is prior to CME-driven storms. CME-driven storms pose more of a problem for Earth-based electrical systems; CIR-driven storms pose more of a problem for space-based assets.Citation: Borovsky, J. E., and M. H. Denton (2006), Differences between CME-driven storms and CIR-driven storms,

[1] The properties of plasmaspheric drainage plumes are examined using cold-plasma measurements in geosynchronous orbit. During high-speed stream-driven storms, 210 plume crossings are collected and statistically analyzed. Plumes that persist for 4 days are common, which was the duration of our search. Plumes weaken with age, becoming narrower in local time with plasma that becomes less dense. Cold-plasma flow velocities are sunward in the plumes, with flow speeds decreasing as the storms progress. Plumes transfer typically 2 Â 10 26 ions/sec (1.2 ton/hr of protons) when they are young, and the rate of transport decreases with plume age. A total of approximately 2 Â 10 31 ions (34 tons of protons) are transported via plumes in the life of a storm. About half of the outer plasmasphere is drained in the first 20 hours of a storm. Large density fluctuations in the plumes indicate that the drainage plumes are lumpy, and large velocity fluctuations of the plasma flow indicate that the drainage plumes may be turbulent. Because of their persistence, drainage plumes are anticipated to be a regular feature of any ongoing geomagnetic storm.

We present observations of the radiation belts from the Helium Oxygen Proton Electron and Magnetic Electron Ion Spectrometer particle detectors on the Van Allen Probes satellites that illustrate the energy dependence and L shell dependence of radiation belt enhancements and decays. We survey events in 2013 and analyze an event on 1 March in more detail. The observations show the following: (a) at all L shells, lower energy electrons are enhanced more often than higher energies; (b) events that fill the slot region are more common at lower energies; (c) enhancements of electrons in the inner zone are more common at lower energies; and (d) even when events do not fully fill the slot region, enhancements at lower energies tend to extend to lower L shells than higher energies. During enhancement events the outer zone extends to lower L shells at lower energies while being confined to higher L shells at higher energies. The inner zone shows the opposite with an outer boundary at higher L shells for lower energies. Both boundaries are nearly straight in log(energy) versus L shell space. At energies below a few 100 keV, radiation belt electron penetration through the slot region into the inner zone is commonplace, but the number and frequency of “slot filling” events decreases with increasing energy. The inner zone is enhanced only at energies that penetrate through the slot. Energy‐ and L shell‐dependent losses (that are consistent with whistler hiss interactions) return the belts to more quiescent conditions.

[1] The interaction of the solar wind and the Earth's magnetosphere is complex and the phenomenology of the interaction is very different for solar wind dominated by interplanetary coronal mass ejections (ICMEs) compared to solar wind dominated by corotating interaction regions (CIRs). We perform a superposed epoch study of the effects of ICME-and CIR-dominated solar wind upon the storm-time plasma at geosynchronous orbit using data from the magnetospheric plasma analyzer (MPA) instruments on board seven Los Alamos National Laboratory (LANL) satellites. Using 78 ICME events and 32 CIR events, we examine the electron and ion plasma sheets that are formed during each type of solar wind driver, at energy-per-charge between $0.1 and 45 keV/q. The results demonstrate that CIR events produce a more significant modulation in the plasma sheet temperature than ICME events, whilst ICME events produce a more significant modulation in the plasma sheet density than CIR events. We attribute these differences to the average speed in the solar wind and a combination of the density of the solar wind and the ionospheric component of the plasma sheet, respectively. We also show that for CIR events, the magnitude of the spacecraft potential is, on average, significantly greater than during ICME-events, with consequent effects upon the performance of instrumentation within this environment.