Solar Wind Ion Observations: Comparison from the Depths of Solar Minimum to the Rising of the Cycle


We report solar wind helium abundance (He/H) and average iron charge states through solar minimum and the rising solar cycle. Speed trends for interplanetary coronal mass ejections seen by STEREO [10] are also presented. ICME case studies contrast the Fe charge states observed in the approach to solar minimum into the rising cycle. During solar minimum, ICME charge states were often similar to the range reported for ambient values. Faster and “hotter” (based on ionization state) ICMEs are being observed as the cycle rises. Using 10-minute data, transient charge state signatures are compared to magnetic cloud boundaries. In one “rising” ICME event, there is a clear and well-contained correspondence between the elevation of iron ionization state and the magnetic cloud’s boundaries, with the post-shock sheath region preceding the cloud remaining at ambient charge state levels. In another “rising” double cloud event, elevated charge states are observed within the magnetic clouds, but are not well contained to the clouds, being observed both within the post-shock sheath region and continuing for nearly a day after the passage of the second magnetic cloud.

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AIP Conference Proceedings



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