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The space hurricane is a newly discovered large-scale three-dimensional magnetic vortex structure that spans the polar ionosphere and magnetosphere. At the height of the ionosphere, it has a strong circular horizontal plasma flow with a nearly zero-flow center and a coincident cyclone-shaped aurora caused by strong electron precipitation associated with intense upward magnetic field-aligned currents. By analyzing the long-term optical observation onboard the Defense Meteorological Satellite Program (DMSP) F16 satellite from 2005 to 2016, we found that space hurricanes in the Northern Hemisphere occur in summer and have a maximum occurrence rate in the afternoon sector around solar maximum. In particular, space hurricanes are more likely to occur in the dayside polar cap at magnetic latitudes greater than 80°, and their MLT (magnetic local time) dependence shows a positive relationship with the IMF (interplanetary magnetic field) clock angle. We also found that space hurricanes occur mainly under dominant positive IMF By and Bz and negative Bx conditions. It is suggested that the stable high-latitude lobe reconnection, which occurs under the conditions of a large Earth’s dipole tilt angle and high ionosphere conductivity in summer, should be the formation mechanism of space hurricanes. The result will give a better understanding of the solar wind–magnetosphere–ionosphere coupling process under northward IMF conditions. 

Simultaneous observations from Defense Meteorological Satellite Program, Swarm, Resolute Bay all‐sky imagers, GPS Total Electron Content and Super Dual Auroral Radar Network, are used to investigate the evolution and key characteristics of the Tongue of Ionization (TOI) being restructured into a polar cap patch. Six satellites crossed the TOI of patch as it moved from the dayside to the nightside. It was initially hot, then a mix of both cold and hot, and finally it became a cold patch. This suggests that cold patch is not only a result of solar extreme ultraviolet radiation, but may also develop when a hot patch cools down. Soft‐electron precipitation and flow shears both contribute to the TOI restructuring and the appearance of polar cap patch. The plasma density of patch at ∼500 km was at least 4 times higher than at ∼800 km. The plasma density enhancement gradually decreased as the patch evolved due to decreased production and transport of cold nightside low‐density plasma. Moreover, the duskward motion of the patch was influenced by changes in the ionospheric convection pattern.

 

Embedded Region 1 and 2 field‐aligned currents (FACs), intense FAC layers of mesoscale latitudinal width near the interface between large‐scale Region 1 and Region 2 FACs, are related to dramatic phenomena in the ionosphere such as discrete arcs, inverted‐V precipitation, and dawnside auroral polarization streams. These relationships suggest that the embedded FACs are potentially important for understanding ionospheric heating and magnetosphere‐ionosphere (M‐I) coupling and instabilities. Previous case studies of embedded FACs have led to the speculation that they may result from enhanced M‐I convection during active times. To explore this idea further, we investigate statistically their occurrence rates under a variety of geomagnetic conditions with a large event list constructed from 17 years of Defense Meteorological Satellite Program observations. The identification procedure is fully automated and explicit. The statistical results indicate that embedded Region 1 and 2 FACs are common, and that they have a higher chance to occur when the level of geomagnetic activity is higher (given by various indices), supporting the idea that they result from enhanced M‐I convection.

 

We present observations during two substorms using simultaneous Time History of Events and Macroscale Interactions During Substorms satellites and all‐sky imagers to determine plasma sheet dynamics associated with substorm auroral onset beads. The multi‐satellite observations showed that the cross‐tail current decreased and the field‐aligned currents increased at the substorm auroral onset, indicating that the satellites detected an initiation of the currents being deflected to the ionosphere. For duskward‐propagating beads, the electric field was tailward, and ions were accumulated closer to the Earth than electrons. The mapped bead propagation speed was close to energetic ion drift speed. Theand electron drift speeds increased duskward and reduced the cross‐tail current at the onset. For dawnward‐propagating beads, the electric field was equatorward/earthward, and electrons were inferred to accumulate earthward of ions. The mapped bead propagation speed was comparable to the dawnwardand electron drift speeds. The duskward ion drift and tail current were reduced, and electrons became the dominant current carrier. We suggest that the plasma species that is responsible for the bead propagation changes with the electric field configuration and that the tail current reduction by the enhanceddrift at onset destabilizes the plasma sheet. Ion and electron outflows substantially increased low‐energy plasma density and may have increased the role ofdrifts. The bead wavelength was comparable to ion gyroradius and thus ion kinetic effects are important for determining the wavelength. In the dawnward‐propagating event, the mode of oscillation in the plasma sheet was suggested to be the sausage‐mode flapping oscillations.