Weekly Highlights of Solar and Geomagnetic Activity, 25 June - 01 July 2012

Weekly Highlights of Solar and Geomagnetic Activity, 25 June - 01 July 2012

Post by SWPC.Webmas.. » Tue, 03 Jul 2012 20:30:08

:Product: Weekly Highlights and Forecasts
:Issued: 2012 Jul 02 1331 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
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#                Weekly Highlights and Forecasts
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Highlights of Solar and Geomagnetic Activity
25 June - 01 July 2012

Solar activity was low to moderate during the week. The first three
days of the period were marked by low level C-class x-ray flares,
the largest of which was a C4/Sf from Region 1512 (S16, L=264,
class/area Dki/290 on 29 June) on 28 June at 0452Z. Region 1512 was
soon overshadowed by Region 1513 (N16, L=218, class/area Dao/120 on
01 July), which produced an impulsive M2/1b flare on 28 June at
1612Z. Subsequently, Region 1513 produced at least one impulsive
M-class event each day for the remainder of the week, the largest of
which was an M2.8/Sb on 01 July at 1918Z. While Region 1513 was the
most prolific flare producer of the regions on the disk, it was
dwarfed in area by Region 1515 (S17, L=204, class/area Ekc/850 on 01
July). Region 1515 appeared on the disk on 27 June and by 01 July
had quadrupled in area. Both Regions 1513 and 1515 ended the week
with beta-gamma magnetic characteristics. There were several CMEs
observed during the week, however none were determined to be
geoeffective.

No proton events were observed at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit began
the period at high levels before decreasing to moderate levels early
on 25 June. Moderate levels continued throughout the week,
increasing to high levels on 01 July at 1320Z.

Geomagnetic field activity ranged from quiet to active levels, with
isolated minor to major storm levels observed at high latitudes late
in the period. The geomagnetic field was at mostly quiet levels from
25-29 June. By 2100Z on 29 June, the phi angle at the ACE spacecraft
switched from positive to negative polarity, indicating the arrival
of the corotating interaction region. Solar wind speed at the ACE
spacecraft, which had ranged between 350-500 km/s during the week,
increased to 700 km/s by 30/1800Z as a coronal hole high speed
stream (CH-HSS) became geoeffective. Concurrently, the Bz component
of the interplanetary magnetic field turned southward, eventually
dipping to -10 to -12 nT while Bt reached 14nT before decreasing to
7 nT by mid-day on 30 June. The geomagnetic field responded with
unsettled to active levels for the remainder of the period. Minor to
major storm levels were observed at high latitudes during 30 June-01
July.

Forecast of Solar and Geomagnetic Activity
02 July - 28 July 2012

Solar activity is expected to be at low to moderate levels, with
more M-class events from Regions 1513 and 1515 likely through 09 -
10 July.

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 08 July and from 17-21 July.

Geomagnetic field activity is expected to begin at unsettled to
active levels, decreasing to mostly quiet to unsettled levels after
03 July until another CH-HSS becomes geoeffective on 27 - 28 July.