26 March


Solar wind conditions were at nominal levels until a shock arrival was
observed in ACE data at 25/1925 UTC, announcing the arrival of the 23
Mar CME. Solar wind speeds increased from approximately 375 km/s to 500
km/s and the total field was enhanced from +2 nT to a maximum value of
+13 nT. The Bz component turned southward following the arrival with a
maximum southward deflection of -10 nT at 25/1938 UTC, and then became
variable in the +9/-8 nT range. Solar wind speed reached a maximum of
554 km/s at 26/0049 UTC before decreasing to end of period values near
410 km/s. Phi angle varied from positive (away) to negative (towards)
sectors through approximately 26/0510 UTC when it settled into a
positive orientation.

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