Solar wind summary (Last 24 hours)

11 March


Following the onset then gradual weakening of a weak, negative-polarity
coronal hole high-speed stream (CH HSS), solar wind parameters returned
to nominal background conditions. Solar wind speed began the period near
340 km/s, but began a slow but steady decline to end the period right
around the 300 km/s mark. Total IMF (Bt) remained steady between 3 nT
and 5 nT, while Bz varied between +/-4 nT. The Phi angle held a mostly
positive (away) orientation through the majority of the period before
slowly oscillating to a slightly negative (towards) solar sector by the
end of the period.

10 March


Measurements at the ACE spacecraft observed a decrease in solar wind
speed for the first half of the period from 345 km/s at 09/1200 UTC to
271 km/s at 10/0000 UTC. The second half of the period saw a gradual
increase in speeds to about 335 km/s at 10/1200 UTC. The Phi angle
gradually rotated from a positive (away) to a negative (towards)
orientation from approximately 09/1900 – 2100 UTC where it remained
predominately negative. Bz ranged from +2 nT to -2 nT with a brief
period of -3 to -4 nT from 10/0728 – 0923 UTC. Bt ranged from 1 nT to 6
nT.

9 March


The coronal hole has not been detected in solar wind data from the ACE
spacecraft yet. Wind speed remained in the upper 300 to lower 400 km/s
range through about 09/0300 UTC where a gradual decrease in speeds to
about 350 km/s was observed. Phi remained in a predominately positive
(away) sector. Bz fluctuated between about +3/-4 nT while Bt was steady
around 3-4 nT.

8 March


Solar wind speed at ACE slowly declined from near 465 km/s at the
beginning of the period to end-of-period speeds of around 375 km/s. The
solar sector remained in a positive (away) orientation. Bz varied
between +/- 3 nT while total field was relatively steady between 2 nT
and 4 nT.

7 March


Solar wind parameters remained slightly enhanced above ambient
background conditions with solar wind speeds averaging near 450 km/s for
the majority of the period. IMF total field strength was again steady
near 4 nT, peaking at 6 nT momentarily, while Bz was as low as -4 nT.
Phi angle remained predominantly at a positive (away) orientation.

6 March


Solar wind parameters continued to experience slightly enhanced
conditions, yet remained at nominal levels. Solar wind speeds averaged
in the mid 400 km/s, but had a slight upward trend throughout the
period. End of period speeds were near 485 km/s. IMF total field
strength was again steady near 4 nT with occasional dips to 1 nT. The Bz
component varied between -/+5 nT and the Phi angle remained
predominantly in a positive (away) orientation with occasional
oscillations into the negative (towards) sector.

5 March


Solar wind parameters indicated nominal, yet slightly enhanced
conditions. Solar wind speeds averaged just under 400 km/s throughout
the period, but indicated a steady increase over time. Speeds began the
period near 360 km/s with an ended-of-period speed just under 450 km/s.
IMF total field strength values occasionally dipped to 3 nT at the
beginning of the period, but held steady the latter half at a constant 6
nT. The Bz component varied between -/+5 nT, and the Phi angle remained
predominantly in a positive (away) orientation.

4 March


Solar wind parameters were at background conditions for most of the
period. Solar wind speeds began the period averaging near 340 km/s,
total field strength values were steady between 1 nT and 5 nT, and the
Bz component varied between -2 nT and +1 nT. At approximately 03/2100
UTC, a solar sector boundary crossing (SSBC) occurred as the Phi angle
went from a negative (toward) orientation to a positive (away)
orientation. Simultaneously, IMF Bt began to increase, reaching a max of
almost 7 nT, while IMF Bz turned southward, seeing a maximum deflection
of almost -4 nT. Solar winds initially decreased slightly, then bounced
back and held fairly steady near 340 km/s. Following a six hour period
back in positive territory, IMF Bz again deflected sharply southward at
approximately 04/0730 UTC, seeing a maximum deflection of -5 nT, with
solar winds picking back up after 04/0830 UTC to average near 370 km/s.

3 March


Solar wind parameters were at nominal levels. Solar wind speeds
steadily decreased from initial values near 380 km/s to end-of-period
values near 340 km/s. Total field strength values were steady near 5 nT
while the Bz component was southward between -1 nT and -5 nT from
02/2300 UTC until just before the end of the period.

2 March


Solar wind parameters were at nominal levels throughout the period.
Solar wind speeds ranged between 365 – 420 km/s. Total field strength
values ranged between 2 nT and 5 nT while the Bz component ranged
between +5 nT and -4 nT. The phi angle was configured in a negative
(toward) sector.