8 December


Solar wind conditions indicated the onset of a co-rotating interaction
region (CIR) followed by CH HSS and possible transient influence from
the 05 Dec CME. The period began at nominal levels with solar wind
speeds in the 320 to 350 range and total field measurements between 1 nT
and 6 nT. By approximately 07/2114 UTC, a slow increase in total field,
solar wind speed, temperature, and density was observed culminating in a
total field increase of 27 nT at 08/0219 UTC. The Bz component went
southward to a maximum of -23 nT while solar wind speeds were near 500
km/s as the CIR reached its maximum strength. Solar wind speed
continued near 500 km/s until a reverse shock occurred at 08/0730 UTC.
Solar wind speed increased again to a maximum of 651 km/s with total
field suddenly decreasing from 10 nT to 5 nT. The reverse shock could
either be related to the CIR or the glancing blow that was expected from
the 05 Dec CME. Phi angle was variable through the period until
approximately 08/0610 UTC when it moved into a mostly positive (away)
sector.

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