14 December


Solar wind parameters, measured at ACE, were indicative of a co-rotating
interaction region (CIR) followed by negative polarity coronal hole high
speed stream (CH HSS) effects. Solar wind speed was initially steady at
around 300 – 330 km/s and increased to around 400 km/s after 14/0045
UTC. Total field strength values ranged from 4 nT to 15 nT while the Bz
component ranged from +14 nT to -11 nT. The phi angle began the period
in a positive (away) sector and transitioned to a negative (toward)
sector around 14/0000 UTC.

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