Investigating EUV Dimming/CME/ICME Events to Understand and Predict Their Source Properties and Interplanetary Effects

Large regions of coronal dimming can accompany coronal mass ejections (CMEs). The dimmings may trace field lines locally opened during the CME and the mass and magnetic flux transported outward by it. We are involved in a program to better understand the initiation, development, and evolution of these transient dimming regions and how their relationship to CMEs. In a first paper Mason et al. (Ap.J., 830, 20, 2016) established a correspondence between the timing and slope of SDO/ EVE dimming regions and of SDO/AIA transient dimming areas, and of the mass and speeds of associated CMEs as obtained from SOHO/ LASCO and STEREO/ SECCHI coronagraph observations.

Here we extend our comparisons of dimming-CME events to their interplanetary counterparts (ICMEs). The ICME properties are important for improving our understanding of the connection between ICME and enhancing our ability to predict the properties of these events. We compare the EVE dimming properties with associated ICME properties including velocity, density, composition and geoeffectiveness. Coronal dimmings presumably indicate that a large quantity of material was removed from low in the corona, and in situ helium and heavy elements may provide constraints on the depth from which the CME material originates. For example, if more energetic CMEs access larger regions lower in the corona, a comparison of dimming-associated CME and ICME properties might show a tendency for relatively fast and massive CMEs to have larger dimmings and enhanced helium abundance. Our ultimate goal is to establish the relationship(s) between the dimming parameters and the ICME parameters and geostorm occurrence and level.