Weekly Highlights of Solar and Geomagnetic Activity, 25 - 31 March 2013

Weekly Highlights of Solar and Geomagnetic Activity, 25 - 31 March 2013

Post by SWPC.Webmas.. » Tue, 02 Apr 2013 20:30:10

:Product: Weekly Highlights and Forecasts
:Issued: 2013 Apr 01 0149 UTC
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#                Weekly Highlights and Forecasts
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Highlights of Solar and Geomagnetic Activity
25 - 31 March 2013

Solar activity was very low. Region 1710 (S21, L=201, class/area
Cao/070 on 29 Mar) produced the largest event of the period with a
B8 flare at 30/1024 UTC. Other activity included a B4 x-ray event
observed at 30/1322 UTC from Region 1708 (N11, L=190, class/area
Dao/090 on 29 Mar) with an associated Type II radio sweep (estimated
shock speed of 814 km/s). No Earth-directed CMEs were observed
during the period.

No proton events were observed at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit was at
high levels for the majority of the period with the exception of 27
and 29 March due to effects from coronal hole high speed stream (CH
HSS) activity.

Geomagnetic field activity was at quiet levels on 25-26 March. Quiet
to active conditions were observed on 27-28 March due to effects
from a favorably positioned CH HSS. Solar wind speed gradually
increased from initial values of approximately 400 km/s to
end-of-day values of approximately 500 km/s. The interplanetary
magnetic field (IMF) Bt values ranged from 1 nT to 11 nT while the
Bz component of the IMF ranged from +7 nT to -11 nT. A further
increase to unsettled to minor storm conditions was observed on
29-30 March due to effects from a second CH HSS. During that period,
solar wind speed remained fairly steady averaging about 550 km/s.
The IMF Bt values ranged from a high of 8 nT to a low of 1 nT while
the Bz component of the IMF ranged from +5 nT to - 7 nT. The field
returned to quiet levels midday on 30 March and remained quiet
through the end of the period.

Forecast of Solar and Geomagnetic Activity
01 April - 27 April 2013

Solar activity is expected to be very low to low throughout the
period. There is a slight chance for M-class activity from 01 - 13
April while Region 1711 (S17, L=159, class/area Cki/420 on 31 Mar)
is on the disk.

No proton events are expected at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit is
expected to be at high levels through 04 April and again from 25
April through the end of the period due to CH HSS effects. The
remainder of the period is expected to be at normal to moderate
levels.

Geomagnetic field activity is expected to begin the period at quiet
levels. Quiet to unsettled conditions are expected from 03-07 April
due to weak CH HSS effects. A return to mostly quiet conditions is
expected on 08-22 April. Quiet to unsettled conditions with a chance
for active periods are possible on 23-26 April due to recurrent CH
HSS effects. The remainder of the period is expected to be at quiet
levels.