Weekly Highlights of Solar and Geomagnetic Activity, 01 - 07 April 2013

Weekly Highlights of Solar and Geomagnetic Activity, 01 - 07 April 2013

Post by SWPC.Webmas.. » Tue, 09 Apr 2013 20:30:34

:Product: Weekly Highlights and Forecasts
:Issued: 2013 Apr 08 0354 UTC
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#                Weekly Highlights and Forecasts
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Highlights of Solar and Geomagnetic Activity
01 - 07 April 2013

Solar activity began the period at very low levels on 01-02 April.
By 03 April, solar activity increased to low levels and continued at
low levels through 04 April due to several low level C-class flares
from Regions 1708 (N11, L=190, class/area Dao/090 on 29 March), 1711
(S19, L=158, class/area Cko/580 on 04 April), and 1713 (N10, L=175,
class/area Dai/130 on 06 April). By 05 April, solar activity reached
moderate levels with an isolated M2 flare at 05/1748 UTC from Region
1719 (N08, L=076, class/area Dsi/150 on 07 April). Earlier on 05
April, a long duration C2 flare was observed at 05/0650 UTC, also
from Region 1719 as it began to rotate onto the east limb. An
associated coronal mass ejection (CME) was observed off the east
limb in SOHO/LASCO C2 imagery beginning at 05/0712 UTC, but was not
Earth-directed. By 06-07 April, solar activity returned to low
levels with the majority of the C-class flares from Regions 1718
(N20, L=109, class/area Dai/140 on 07 April) and 1719. No
Earth-directed CMEs were observed during the reporting period.

No proton events were observed at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit was at
high levels on 01-05 April and decreased to moderate levels by 06-07
April. The maximum weekly flux value of 5166 pfu was observed at
02/1735 UTC.

Geomagnetic field activity was at quiet levels with isolated active
periods at high latitudes mid-day on 01 and 07 April. Solar wind
speed began the period decreasing from approximately 480 km/s to a
low near 250 km/s by late on 05 April while the total field strength
slowly increased from 2 nT to 6 nT. By Early on 06 April, solar wind
speed started to increase to 340-370 km/s while total field strength
increased to 5-7 nT. Solar wind speed was relatively constant near
the 330-350 km/s range through the end of the reporting period. Phi
angle was mostly negative (towards) through approximately 07/1500
UTC when a change to a more positive (away) sector occurred.

Forecast of Solar and Geomagnetic Activity
08 April - 04 May 2013

Solar activity is expected to be at very low to low levels with a
chance for M-class flaring from 08-19 April as Regions 1713, 1718,
and 1719 continue to transit across the visible disk. From 20 April
until the end of the forecast period, very low to low levels are
expected.

No proton events are expected at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit is
expected to be at normal to moderate levels with a chance for high
levels on 24 April-02 May due to recurrent coronal hole high speed
stream (CH HSS) effects.

Geomagnetic field activity is expected to be quiet to unsettled on
08-09 April due to weak CH HSS effects. Mostly quiet conditions will
prevail until another CH HSS moves into geoeffective position on 23
April. Quiet to unsettle conditions with a chance for isolated
active periods are expected on 23 April with quiet to unsettled
levels on 24 April. Another CH HSS is expected to become
geoeffective on 25-26 April causing unsettled to active conditions
with minor storm periods possible. Conditions are expected to return
to mostly quiet levels by 27 April through the end of the forecast
period.