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Solar wind summary (Last 24 hours)

21 December

Solar wind parameters were indicative of a nominal solar wind
environment. Solar wind speeds were relatively steady in the 340 – 380
km/s range. Total field strength values were steady near 4 nT while the
Bz component ranged between +4 nT and -4 nT. The phi angle was
predominately configured in a negative (toward) sector, with some
variability to a positive (away) sector between 21/0000 – 0800 UTC.

20 December

Solar wind parameters, measured at ACE, were indicative of a nominal
solar wind environment. Solar wind speed was steady in the 350 – 400
km/s range. Total field strength values were steady near 4 nT while the
Bz component ranged from +4 nT to -5 nT. The phi angle remained
configured in a negative (toward) sector throughout the period.

19 December

Solar wind parameters, measured at ACE, reflected nominal background
conditions. Solar wind speeds remained between 331 and 390 km/s,
reaching a peak speed of 390 km/s at 1444 UTC. The total field strength
values ranged from 2 nT to 6 nT while the Bz component fluctuated
between +5/-6 nT. The phi angle was predominately in a negative (toward)
orientation for the past 24 hours with an occasional interlude into a
positive (away) orientation.

18 December

Solar wind parameters, measured at ACE, reflected nominal background
conditions. Solar wind speed began the period near 400 km/s, reached a
peak speed of 447 km/s, then steadily decreased to end the period near
355 km/s. The total field strength values ranged from 2 nT to 4 nT while
the Bz component fluctuated between +/-4 nT. The phi angle remained in a
negative (away) orientation for the past 24 hours.

17 December

Solar wind parameters, measured at ACE, reflected the continued decline
of effects from a waning coronal hole high speed stream (CH HSS). Solar
wind speed began the period near 440 km/s with occasional speeds as high
as 458 km/s. They then steadily decreased to end the period just under
380 km/s. The total field strength values ranged from 2 nT to 4 nT while
the Bz component fluctuated between +3 nT to -4 nT. The phi angle has
remained in a negative (away) orientation for the past 24 hours.

16 December

Solar wind parameters, measured at ACE, were indicative of a nominal
solar wind environment. Solar wind speed ranged from 450 – 500 km/s
throughout the period. The total field strength values ranged from 2 nT
to 9 nT and the Bz component ranged from +5 nT to -4 nT. The phi angle
transitioned from a positive (away) sector to a negative (toward) sector
at around 16/0800 UTC.

15 December

Solar wind parameters were indicative of waning negative polarity
coronal hole high speed stream (CH HSS) influence and the weak passage
of a pair of CMEs from 12 Dec. Solar wind speed values began the period
steady at around 400 km/s but began to increase after 14/1400 UTC with
the likely arrival of the first of the 12 Dec CMEs. Wind speed values
underwent another minor enhancement at 14/1830 UTC, likely with the
arrival of the second of the 12 Dec CMEs, and reached a peak near 600
km/s at around 14/2000 UTC. After 15/0130 UTC, wind speeds began to
slowly decrease and ended the period near 470 km/s. The total field
strength values ranged from 5 nT to 10 nT while the Bz component ranged
from +10 nT to -8 nT.

14 December

Solar wind parameters, measured at ACE, were indicative of a co-rotating
interaction region (CIR) followed by negative polarity coronal hole high
speed stream (CH HSS) effects. Solar wind speed was initially steady at
around 300 – 330 km/s and increased to around 400 km/s after 14/0045
UTC. Total field strength values ranged from 4 nT to 15 nT while the Bz
component ranged from +14 nT to -11 nT. The phi angle began the period
in a positive (away) sector and transitioned to a negative (toward)
sector around 14/0000 UTC.

13 December

Solar wind parameters, measured at ACE, were indicative of a nominal
solar wind environment. Solar wind speed decreased from initial values
near 310 km/s to end-of-period values near 270 km/s. Total field
strength was steady near 2 nT throughout the period while the Bz
component ranged from +2 to -2 nT. The phi angle remained configured in
a positive (away) sector.

12 December

Solar wind, as measured by the ACE spacecraft, remained at background
conditions throughout the period. Wind speed reached a peak of 371 km/s
at 11/1410 UTC before steadily decreasing to end the period near 320
km/s. The total interplanetary magnetic field fluctuated between 0 nT
and 3 nT while the Bz component wavered between +1 nT/-3 nT. Phi angle
was positioned in a predominately positive (away) orientation, but had
periodic oscillations into a negative (toward) orientation throughout
the period.