Solar wind summary (Last 24 hours)

12th August


Solar wind speed, as measured by the ACE spacecraft, indicated residual
CH HSS effects followed by a possible transition into another CH HSS.
Solar wind speeds were steady at about 425 km/s through about 11/2100
UTC when a gradual rise to 550 km/s was observed through 12/0415 UTC.
Wind speeds gradually decreased to about 480 km/s by period’s end. Total
IMF (Bt) ranged between 2 to 9 nT through 11/1600 UTC when field values
remained fairly steady at 5 to 6 nT. The Bz component was variable
between +/- 7 nT through the period. Phi angle began the period in a
negative (towards) orientation through 11/1552 UTC where a switch to a
positive (away) sector was observed. By 11/2144 UTC, phi angle switched
back to a more positive orientation and generally remained so through
period’s end.

11th August


Solar wind speed at the ACE spacecraft rose from about 300 km/s at the
beginning of the period to end near 425 km/s as a weak coronal hole high
speed stream became geoeffective. Peak speed appeared to be around 460
km/s. Bt reached 11 nT, while Bz was mostly neutral or positive, with a
maximum southward deflection around -4 nT early in the period. Phi was
generally negative.

10th August


Solar wind parameters, measured at ACE, were indicative of background
solar wind conditions. Solar wind speeds exhibited a steady decline
through the period from a high of about 375 km/s to near 300 km/s by
period’s end. The total interplanetary magnetic field (Bt) ranged
between 3 nT and 7 nT. The Bz component was mostly north with some
southward deviation to -5 nT after 10/0545 UTC. The phi angle was
predominately oriented in a positive (away) solar sector through about
10/1000 UTC where a switch to a more negative (towards) orientation was
observed.

9th August


Solar wind parameters, measured at ACE, were indicative of background
solar wind conditions. Solar wind exhibited a slow decline in speeds
through the period from a high of about 400 km/s to near 350 km/s by
period’s end. The total interplanetary magnetic field (Bt) ranged
between 1 nT and 6 nT while the Bz component was mostly north with some
southward deviation to -3 nT early on 09 August. The phi angle was
predominately oriented in a positive (away) solar sector with
variability into a negative (towards) sector between 08/1200-1550 UTC
and again from 09/0730-1200 UTC.

8th August


Solar wind parameters, measured at ACE, suggested the return of nominal
conditions following the recovery from a positive polarity coronal hole
high speed stream (CH HSS). During the period, solar wind speeds were
generally variable between 350 km/s to 400 km/s while IMF total field
strength ranged between about 2 nT to near 7 nT. IMF Bz was
predominately negative with a maximum deviation of -5 nT. The phi angle
was in a positive (away) orientation through about 08/0700 UTC when a
gradual rotation to a negative (toward) orientation occurred.

7th August


Solar wind parameters, measured at ACE, suggested the return of nominal
conditions following the recovery from a coronal hole high speed stream
(CH HSS). Solar wind speeds decreased slightly from speeds near 480 km/s
to near 360 km/s. IMF Total field remained steady between 4 and 6 nT
while Bz varied mostly between 2 nT and -3 nT. The phi angle was
predominately positive (away) throughout the period.

6th August


Solar wind parameters, measured at ACE, suggested possible continued
weak coronal hole high speed stream (CH HSS) influences. Solar wind
speeds averaged near 450 km/s. IMF Total field decreased from around 7
nT at the onset of the period to around 4nT to end it. Bz was variable
between 3 nT and -2 nT. The phi angle was predominately positive (away)
throughout the period.

5th August


Solar wind parameters observed at ACE displayed slightly elevated
conditions with solar wind speeds averaging 470 km/s, increased over
from near 400 km/s over the past 24 hours. Associated with elevated
speeds was an increase in Bt with average potential near 8 nT. Bz was
mostly positive, but a period near -5 nt was observed over the past few
hours. Phi angle was steady at a positive (away) orientation. These
conditions are believed to be the result of a high speed stream from CH
76, a positive polarity feature.

4th August


Solar wind displayed an upward trend beginning the period at 388 km/s
and ending near 440 km/s. Total field ranged from 2 nT to 8 nT with the
Bz component predominately negative reaching a maximum southward extent
of -6 nT. Prolonged periods of southward Bz occurred between
03/1531-2058 UTC and 04/0606-0947 UTC. Phi angle remained in a mostly
positive (away) orientation through the period.

11 April


ACE data indicated nominal conditions during the period. Wind speed was
variable ranging between about 360 km/s to near 440 km/s. IMF total
field intensity ranged from 3 nT to 8 nT. The Bz component of the IMF
ranged from 5 nT to -4 nT while IMF Phi data indicated a predominately
positive polarity (away) solar sector.