25 December


ACE data indicated nominal solar wind conditions. Solar wind speed began
the period just under 290 km/s, trailing off to near 250 km/s before
beginning a gradual climb to nearly 340 km/s at its peak around 25/0400
UTC. Just after it reached its max, it began a steady decrease through
the end of the period, where it ended as it began at just below 290
km/s. IMF Bt was steady between 3 to 6 nT range for the first half of
the period, then began climbing to 10 nT to 12 nT, where it remained
through the end of the period. IMF Bz was predominantly southward during
the first half of the period, before fluctuating between +/-5 nT through
0400 UTC, the dropping even more southward to end the period at a steady
-9 nT. Phi data indicated the Earth was within a positive-polarity
(away) solar sector through approximately 0400 UTC when it made a slow
but steady transition to a negative (towards) orientation.

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