Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 058 Issued at 2200Z on 27 Feb 2012
IA. Analysis of Solar Active Regions and Activity from 26/2100Z
to 27/2100Z: Solar activity was low during the past 24 hours. There
was one C-class flare, a C2/Sf at 26/2141Z from the spotless plage
Region 1421 (N14E62). Region 1423 (N18E15) is the largest group on
the disk but is small and unimpressive. A filament eruption was
observed over the north-east limb in the SDO AIA 304 imagery at
about 27/1433Z and appears to be associated with a CME seen in LASCO
imagery over the north pole. Another CME was noted in LASCO at
27/2012Z over the west limb but STEREO-A EUVI images clearly show
that the solar source region behind the west limb. Neither of these
CMEs are expected to be geoeffective.
IB. Solar Activity Forecast: Solar activity is expected to be very
low. There is, however, a slight chance for an isolated C-class
flare.
IIA. Geophysical Activity Summary 26/2100Z to 27/2100Z:
The geomagnetic field ranged from quiet to minor storm levels with an
isolated period of major storm levels at high latitude. A weak shock
passed the ACE spacecraft at 26/2058Z and was followed by a sudden
impulse at Earth at 26/2141Z. Unsettled to active levels prevailed
for the subsequent nine hours, followed by about nine hours of
mostly quiet levels. However, solar wind data showed a sustained
interval of moderately negative Bz from about 1000-1800Z and
conditions increased to active levels from 1200-2100Z with a minor
storm period during the last three hours of the interval. The timing
and solar wind signatures suggest that disturbance is most likely
due to passage of the CME that was initiated early on 24 February.
The greater than 10 MeV protons continued to be elevated but were on
the decline during the day with end-of-period values less than 1
PFU. Further analysis and comparison with ACE EPAM and ACE SIS show
that these particles were likely also associated with the 24
February CME.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be generally unsettled for the first day (28 February)
as effects from the current disturbance persist. Predominantly quiet
levels are expected for the second and third days (29 February - 01
March).
III. Event Probabilities 28 Feb-01 Mar
Class M 01/01/01
Class X 01/01/01
Proton 01/01/01
PCAF green
IV. Penticton 10.7 cm Flux
Observed 27 Feb 106
Predicted 28 Feb-01 Mar 105/105/105
90 Day Mean 27 Feb 128
V. Geomagnetic A Indices
Observed Afr/Ap 26 Feb 007/006
Estimated Afr/Ap 27 Feb 013/016
Predicted Afr/Ap 28 Feb-01 Mar 009/010-006/005-006/005
VI. Geomagnetic Activity Probabilities 28 Feb-01 Mar
A. Middle Latitudes
Active 20/05/05
Minor storm 05/01/01
Major-severe storm 01/01/01
B. High Latitudes
Active 15/15/15
Minor storm 15/10/10
Major-severe storm 05/05/05
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