Comment Section

varSITI campaign event
The largest geomagnetic storm at Earth for this solar cycle, this event registered a Dst peak below -200. Based on both the in-situ signature of the event and the ENLIL solar wind prediction for this date, I think it is likely a CIR played a role in making it so strong. There is a strong coronal hole at the South Pole and the ENLIL simulation ([[1]]) shows a fairly fast stream that interacts with the CME, and this fast speed stream (~600 km/s) shows up in ACE data as well. Based on the C2 and C3 images for the day, it appears there is a slow CME launching around noon on the 14th with a small but visible filament. On the morning of the 15th a partial halo CME, associated with a long duration flare that fell just short of M class (C9.1) and from the same active region (AR 12297), launched propagating to the East of the Sun Earth line. I think it is likely that an interaction between the CME+shock of this event and the previous blob CME, as well as the added energy from the CIR and fast speed stream behind the CME caused the severity of the geomagnetic activity at the Earth (Hess)

Image Data

These are in-situ plots based on the ACE daily text files, I will update them when the cdf data becomes available. In these plots the shock is very clear, but beyond that any ejecta signature is weak and there does not appear to be any strong Magnetic cloud. But there are two clear and distinct periods of strong -Bz. (Hess)