Solar wind summary (Last 24 hours)

11 December


Solar wind parameters were at background levels for most of the period.
Solar wind speed, as measured by the ACE spacecraft, began the period
near 410 km/s, reached a peak speed of 420 km/s at 10/0804 UTC, and
ended the period near 360 km/s. Total IMF started and ended the period
near 3 nT, varying slightly between 0 nT and 4 nT throughout the
period. Bz fluctuated between +/-3 nT throughout the period. The phi
angle remained in a predominantly positive (away) orientation for most
of the period, but exhibited signs of negative (towards) oscillations
intermittently through the period.

10 December


Solar wind parameters were indicative of waning CH HSS conditions. Solar
wind speed steadily decreased from 464 km/s to begin the period to just
over 400 km/s at the end of the period. Total IMF averaged near 4 nT,
but varied intermittently between 1 nT and 6 nT throughout the period.
Bz remained mostly southward, reaching a maximum southward deviation of
-5 nT at 10/0615 UTC, but ended the period at +1 nT. Phi angle had
slight oscillations between positive (away) and negative (towards)
solar sectors, but remained in a mostly positive (away) orientation.

9 December


Solar wind continued to be under the influence of a CH HSS during the
period. Solar wind speed decreased from approximately 688 km/s to 455
km/s while the total field decreased from 6 nT to 3 nT. The Bz
component did not vary much beyond +/-4 nT. Phi angle was mostly
positive (away) with minor deviations into a negative (towards) sector.

8 December


Solar wind conditions indicated the onset of a co-rotating interaction
region (CIR) followed by CH HSS and possible transient influence from
the 05 Dec CME. The period began at nominal levels with solar wind
speeds in the 320 to 350 range and total field measurements between 1 nT
and 6 nT. By approximately 07/2114 UTC, a slow increase in total field,
solar wind speed, temperature, and density was observed culminating in a
total field increase of 27 nT at 08/0219 UTC. The Bz component went
southward to a maximum of -23 nT while solar wind speeds were near 500
km/s as the CIR reached its maximum strength. Solar wind speed
continued near 500 km/s until a reverse shock occurred at 08/0730 UTC.
Solar wind speed increased again to a maximum of 651 km/s with total
field suddenly decreasing from 10 nT to 5 nT. The reverse shock could
either be related to the CIR or the glancing blow that was expected from
the 05 Dec CME. Phi angle was variable through the period until
approximately 08/0610 UTC when it moved into a mostly positive (away)
sector.

7 December


Solar wind continued to be at nominal conditions with wind speeds
ranging from approximately 300 km/s to 350 km/s. Total field ranged
from 2 nT to 5 nT with the Bz component mostly southward ranging from +2
nT to -5 nT. Phi angle slowly transitioned from near neutral to a
positive (away) orientation during the period.

6 December


Solar wind parameters, as measured by the ACE spacecraft, remained at
background conditions. Solar wind speed reached a peak of 381 km/s at
05/1009 UTC, but remained in the mid 300 km/s range for most of the
period. Total IMF fluctuated slightly between 5 nT and 1 nT for the
first half of the period, before steadily climbing from 1 nT to end the
period near 4 nT. IMF Bz varied between +4 nT and -2 nT. Phi angle
remained in a predominately positive (away) orientation throughout the
period, with a brief oscillation to negative (towards) near the end of
the period.

5 December


Solar wind parameters, as measured by the ACE spacecraft, remained at
background conditions throughout the period. Solar wind speed reached an
isolated peak of 422 km/s at 04/1350 UTC, but remained in the mid 300
km/s range for most of the period. Total IMF steadily fluctuated between
4 nT and 6 nT with isolated dips to near 2 nT. IMF Bz remained negative
for most of the period with isolated northward transitions to near 1 nT
and 3 nT. Phi angle remained in a predominately positive (away)
orientation throughout the period.

4 December


Solar wind parameters, as measured by the ACE spacecraft, indicated
background conditions. Solar wind speed ranged from 364 km/s to 429 km/s
throughout most of the period. Conditions finally began to settle down
with wind speeds maintaining a steady speed near 360 km/s by the end of
the period. Total IMF varied between 4 nT and 9 nT, while the Bz
component fluctuated between -6 nT and +4 nT throughout the period. Phi
angle began the period in a predominately positive (away) orientation,
but did oscillate into a negative (towards) orientation briefly, from
approximately 03/2345 UTC to 04/0626 UTC, when it returned to a positive
position.

3rd December


Solar wind conditions indicated lingering effects of the coronal hole
high speed stream (CH HSS). Solar wind speed began the period near 430
km/s but steadily decreased to below 400 km/s by the end of the UTC day.
Speeds then fluctuated between 440 km/s and 365 km/s over the next few
hours before ending the period right at 400 km/s. The IMF total field
showed a steady decline from 10 nT at the beginning of the period, down
to 5 nT by the end of the period. The Bz component varied slightly
between +2/-2 nT through most of the period. A brief northward period
occurred near 03/0400 UTC where Bz reached +5 nT for a few hours before
dropping to -5 nT, where it remained for the remainder of the period.
Phi angle was predominately positive (away) throughout the day.

2nd December


Solar wind conditions reflected the waning influence of a positive
polarity coronal hole high speed stream (CH HSS). Solar wind speed
reached a maximum of 529 km/s early in the period, then began a steady
decrease throughout the rest of the period, ending at 430 km/s. Total
field remained near 10 nT the entire period. The Bz component of the IMF
remained positive throughout most of the period, only turning negative
just after 02/0800 UTC. Phi angle was mostly positive (away) with minor
deviations into negative (towards) territory throughout the period.