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Abstract Dawnside auroral polarization streams (DAPS) are fast eastward flows in the dawn convection cell of Earth's ionosphere. With a steep flow gradient near the interface between Region 1 and 2 currents and a peak poleward of it, DAPS were suggested to be responsible for instabilities and dramatic events in the magnetosphere‐ionosphere (M‐I) system. To predict these events, it is important to investigate when and where DAPS prefer to occur and how they are related to other M‐I phenomena. We conduct this investigation statistically using 10 years of Swarm data and find that DAPS under sunlit and dark ionospheric conditions exhibit different dependencies on magnetic local times and geomagnetic activities, reflecting a complicated interplay between magnetotail dynamics and ionospheric conductance. The statistical results also reveal a strong correlation between DAPS and embedded Region 2 currents. These findings provide new insights into the DAPS generation mechanism. 

Abstract We examine the statistical distribution of large‐scale Birkeland currents measured by the Active Magnetosphere and Planetary Electrodynamics Response Experiment in four unique categories of geomagnetic activity for the first time: quiet times, storm times, quiet‐time substorms, and storm‐time substorms. A novel method is employed to sort data into one of these four categories, and the categorizations are provided for future research. The mean current density is largest during substorms and its standard deviation is largest during geomagnetic storms. Current densities which are above a low threshold are more likely during substorms, but extreme currents are far more likely during geomagnetic storms, consistent with a paradigm in which geomagnetic storms represent periods of enhanced variability over quiet times. We demonstrate that extreme currents are most likely to flow within the Region 2 current during geomagnetic storms. This is unexpected in a paradigm of the current systems in which Region 1 current is generally larger.