Viewing archive of Friday, 28 September 2012
Solar activity report
Any mentioned solar flare in this report has a scaling factor applied by the Space Weather Prediction Center (SWPC). Because of the SWPC scaling factor, solar flares are reported as 42% smaller than for the science quality data. The scaling factor has been removed from our archived solar flare data to reflect the true physical units.
Report of Solar-Geophysical Activity 2012 Sep 28 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 272 Issued at 2200Z on 28 Sep 2012IA. Analysis of Solar Active Regions and Activity from 27-2100Z to 28-2100Z Solar activity was at low levels. Region 1577 (N08W41)
produced a long duration C3/1f flare at 27/2357Z. The event began
with a filament eruption located northwest of and adjacent to the
region with a subsequent dual ribbon flare. Associated with this
event was an Earth-directed, asymmetric, full-halo CME first visible
in SOHO LASCO C2 and C3 imagery at 28/0018Z and 28/0030Z,
respectively. The plane-of-sky speed through both fields averaged
1034 km/s with a computed radial velocity of 872 km/s. Little
change was observed for the remainder of the disk and limb. No
other Earth-directed CMEs were observed.
IB. Solar Activity Forecast
Solar activity is expected to be at
low levels with a slight chance for M-class activity all three days
of the forecast period (29 - 30 September and 01 October).
IIA. Geophysical Activity Summary 27-2100Z to 28-2100Z
The geomagnetic field was at quiet levels. ACE satellite
measurements indicated a steady decline in wind velocity from about
400 km/s to near 325 km/s while the Bz component of the
interplanetary magnetic field did not vary much beyond +/- 2 nT.
The greater than 10 MeV proton flux at geosynchronous orbit exceeded
threshold at 28/0300Z, reached a maximum of 28 pfu at 28/0445Z and
decayed below threshold at 28/1040Z. At the time of this report,
flux levels were still elevated at about 5 pfu. This event was
believed to be associated with the C3/1f flare observed late on 27
September.
IIB. Geophysical Activity Forecast
Geomagnetic field activity is
expected to be at predominately quiet levels on day one (29
September) and through midday on day two (30 September). By late
on day two, active levels with a chance for minor to major storm
periods are expected due to the arrival of the Earth-directed CME
observed early on 28 September. On day three (01 October),
continued minor to major storm conditions are expected early in the
day, decreasing to mostly quiet to unsettled levels with isolated
active periods as effects from the CME wane.
III. Event Probabilities 29 Sep to 01 Oct
| Class M | 10% | 10% | 10% |
| Class X | 01% | 01% | 01% |
| Proton | 01% | 01% | 01% |
| PCAF | green | ||
IV. Penticton 10.7 cm Flux
Observed 28 Sep 138 Predicted 29 Sep-01 Oct 135/135/130 90 Day Mean 28 Sep 125
V. Geomagnetic A Indices
Observed Afr/Ap 27 Sep 003/004 Estimated Afr/Ap 28 Sep 002/003 Predicted Afr/Ap 29 Sep-01 Oct 004/005-018/035-018/025
VI. Geomagnetic Activity Probabilities 29 Sep to 01 Oct
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 05% | 35% | 35% |
| Minor storm | 01% | 25% | 30% |
| Major-severe storm | 01% | 05% | 05% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 15% | 10% | 10% |
| Minor storm | 15% | 25% | 25% |
| Major-severe storm | 05% | 50% | 65% |
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