Weekly Highlights of Solar and Geomagnetic Activity, 19 - 25 March 2012

Weekly Highlights of Solar and Geomagnetic Activity, 19 - 25 March 2012

Post by SWPC.Webmas.. » Tue, 27 Mar 2012 20:30:07

:Product: Weekly Highlights and Forecasts
:Issued: 2012 Mar 26 1340 UTC
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#                Weekly Highlights and Forecasts
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Highlights of Solar and Geomagnetic Activity
19 - 25 March 2012

Solar activity has been at low to moderate levels for the past seven
days. The largest event of the period was a M1 x-ray event on 23
March at 1940 UTC from Region 1445 (S24, L=026, class/area Fho/280
on 25 March). Region 1445 rotated onto the southeast limb of the
solar disk late on 23 March and has since dominated in solar
activity, producing multiple C-class x-ray events. Region 1444 (N19,
L=067, class/area Cao/060 on 25 March) emerged on 23 March and has
also been active, producing multiple C-class x-ray events. Both
Regions, 1445 and 1444, produced CMEs on 25 March, however very
little effect is expected here at Earth. The remaining regions on
the solar disk remained rather quiet and stable.

No proton events were observed at geosynchronous orbit during the
summary period.

The greater than 2 MeV electron flux at geosynchronous orbit was at
pre***ly high levels for the duration of the summary period.
However, on 23 and 25 March, moderate levels were observed.

The geomagnetic field ranged from quiet to active levels with an
isolated period at minor storm levels at high latitudes. On 19
March, pre***ly quiet levels were observed with an isolated
active period measured early in the day, in response to the arrival
of a CME from 15 March. Quiet conditions prevailed from 20 March to
late on 22 March, when a solar sector boundary (SSB) crossing was
measured by the ACE spacecraft. Following the SSB, quiet to
unsettled levels were seen from 22 - 23 March. On 24 March, active
levels with an isolated minor storm period was observed as a small
coronal hole high speed stream (CH HSS) moved into a geoeffective
position. This CH HSS was short lived with measurements by the ACE
spacecraft indicating a quick rise in solar wind speeds to around
500 km/s followed by a quick decrease to nominal background levels.
On 25 March, activity returned to quiet levels.

Note: There is a gap in data from the GOES 15 spacecraft from late
on 21 March through mid 23 March. This gap can be seen in the GOES
15 x-ray plot.

Forecast of Solar and Geomagnetic Activity
26 March - 21 April 2012

Solar activity is expected to be at low to moderate levels.
Pre***ly low levels are expected from 26 - 28 March, when old
Region 1429 rotates back onto the northeast limb. M-class flare
probabilities are expected to increase from 28 March - 11 April as
old Region 1429 progresses across the solar disk. A return to low
levels is expected to prevail for the remainder of the period, 12 -
21 April.

No proton events are forecast from 26 - 30 March. An increase to a
slight chance for proton events is forecast from 31 March - 11 April
as old Region 1429 populates the visible disk. A return to
background proton flux levels is expected from 12 April - 21 April.

Electrons, greater than 2 MeV, are expected to be at normal to
moderate levels from 26 - 28 March. From 29 March - 03 April,
moderate to high levels are expected. From 04 - 13 April, a return
to normal to moderate levels is expected. Moderate to high levels
are expected from 14 - 18 April. A return to normal levels is
expected for the remainder of the period.

The geomagnetic field is expected to be at mostly quiet levels from
26 - 27 March. Quiet to active levels are expected from 28 -29 March
in response to the effects of a CH HSS. Pre***ly quiet levels
are expected from 30 March - 12 April. An increase to quiet to
active levels is expected from 13 - 14 April in response to a CH
HSS. Quiet levels are expected to prevail for the remainder of the
period.