10th December

The southern pole coronal hole high speed stream (CH HSS) remained
geoeffective although it was beginning to show signs of decay. Solar
wind speed at the ACE spacecraft began the period in the low 500 km/s
range and ended near 450 km/s. Phi began the period in the negative
sector, but was variable after 09/1800 UTC. Bt reached 8 nT while Bz
dipped to -5 nT.

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