16 January

The solar wind environment at the ACE spacecraft continued to reflect a
waning coronal hole high speed stream. Wind speed began the period at
485 km/s and remained fairly steady until just after 15/1600 UTC when a
brief solar sector boundary crossing (SSBC) occurred. Winds briefly
spiked to reach a peak of 556 km/s before quickly returning to just
below 480 km/s. Speeds then showed a slow but steady decline and ended
the period at 400 km/s. Phi angle began the period in a fairly constant
negative (Toward) orientation, but shifted briefly to a positive
orientation between 15/1630-1930 UTC. Following the brief SSBC, Phi
oscillated between positive and negative for the remainder of the
period. Bt remained steady near 3 nT through the period. Bz was
predominantly neutral throughout most of the period, then varied between
-/+ 2 nT the last eight hours.

Leave a Reply