Viewing archive of Tuesday, 25 October 2011

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 2011 Oct 25 2200 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 298 Issued at 2200Z on 25 Oct 2011

IA. Analysis of Solar Active Regions and Activity from 24-2100Z to 25-2100Z

Solar activity was at low levels due to a single C1 x-ray event from Region 1330 (N08E31). Regions 1325 (N15E03), 1327 (S21W54) and 1330) indicated some decay in area. The remaining regions were unchanged.
IB. Solar Activity Forecast
Solar activity is expected to be low with a slight chance for M-class activity all three days (26 - 28 October). Regions 1324 (N12W26) and 1330 (N08E29) are the most likely to produce moderate level activity.
IIA. Geophysical Activity Summary 24-2100Z to 25-2100Z
The geomagnetic field ranged from quiet to severe storm levels. The period began with unsettled to minor storm levels. By 25/0000Z, minor to major storm levels, with high latitude severe storm levels, were observed. From 25/0300Z - 0900Z, active to major storm levels predominated followed by quiet to active levels for the remainder of the period. This increase in activity was likely associated with effects following the arrival of CME activity, first observed on 22 October. Following the interplanetary shock observed at the ACE spacecraft on 24/1748Z. ACE registered increases in wind speed, temperature and density. Solar wind velocities increased from a steady 350 km/s to about 525 km/s, and remained at that speed throughout the period. The interplanetary magnetic field (IMF) Bt increased to above 20 nT from about 24/2000Z through 25/1300Z and gradually decreased to about 8 nT by the end of the period. The Bz component of the IMF reached southward values of -20 nT from about 24/2000Z through 25/0000Z. The remainder of the period observed mostly northward Bz.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to be at quiet to unsettled levels, with isolated active periods on day one (26 October), due to lingering effects from the CME that impacted Earth on 24 October. Mostly quiet conditions are expected on day two (27 October). By day three (28 October), quiet to unsettled levels are expected due to effects from a recurrent coronal hole high speed stream.
III. Event Probabilities 26 Oct to 28 Oct
Class M20%20%20%
Class X01%01%01%
IV. Penticton 10.7 cm Flux
  Observed       25 Oct 139
  Predicted   26 Oct-28 Oct  140/140/135
  90 Day Mean        25 Oct 123
V. Geomagnetic A Indices
  Observed Afr/Ap 24 Oct  016/023
  Estimated     Afr/Ap 25 Oct  028/040
  Predicted    Afr/Ap 26 Oct-28 Oct  007/012-005/005-007/007
VI. Geomagnetic Activity Probabilities 26 Oct to 28 Oct
A. Middle Latitudes
Minor storm05%01%05%
Major-severe storm01%01%01%
B. High Latitudes
Minor storm15%05%10%
Major-severe storm01%01%01%

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