Joint USAF/NOAA Report of Solar and Geophysical Activity 20 Jan 2005

Status Report From: Space Weather Prediction Center (NOAA)
Posted: Thursday, January 20, 2005


Prepared jointly by the U.S. Dept. of Commerce, NOAA, Space Environment Center and the U.S. Air Force. Updated 2005 Jan 20 2210 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity SDF Number 020 Issued at 2200Z on 20 Jan 2005

IA. Analysis of Solar Active Regions and Activity from 19/2100Z to 20/2100Z: Solar activity was high. Region 720 (N14W70) produced an X7/2b flare at 0701 UTC, which was accompanied by Type II and Type IV radio sweeps. There is one image from the LASCO C2 coronagraph which shows an associated CME off the northwest limb at 0654 UTC. However, shortly after this observation the coronagraph data became difficult to use due to high levels of energetic particles. Region 720 continues to be large, with a sheared magnetic delta configuration along an east-west polarity inversion line.

IB. Solar Activity Forecast: Solar activity is expected to be moderate to high. Region 720 continues to have potential for producing an additional major flare. The location of Region 720 on the disk also implies that there is a fair chance for more energetic particles in association with future major flare activity.

IIA. Geophysical Activity Summary 19/2100Z to 20/2100Z: The geomagnetic field was quiet to active during the past 24 hours. Solar wind speeds were elevated (700-900 km/s) from the start of the interval up through at least 0700 UTC, after which the ACE real-time SWEPAM data became unusable due to elevated energetic particle flux. The interplanetary magnetic field, however, was weak with fluctuations between -4 nT to +6 nT. A new injection of protons was observed at 0650 UTC in association with the X7 flare. The greater than 100 MeV protons rose rapidly and attained a maximum of 652 PFU at 0710 UTC. The 100 MeV flux has been declining steadily since then. This high flux level makes this the largest greater than 100 MeV proton event observed since October 1989. A greater than 10 MeV proton event was in progress at the time of the new injection, but the new particles quickly increased the flux from initial values around 40 PFU to a peak value in the past 24 hours of 1860 PFU at 0810 UTC.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be predominantly unsettled to active for the next three days. Today's CME (associated with the X7 flare) is not expected to produce anything more than a glancing blow due to its direction away from the Sun-Earth line. The greater than 10 MeV flux is expected to remain above event threshold for at least another 24 hours.

III. Event Probabilities 21 Jan-23 Jan

  • Class M 90/90/80
  • Class X 30/30/20
  • Proton 99/80/50
  • PCAF in progress

IV. Penticton 10.7 cm Flux

  • Observed 20 Jan 123
  • Predicted 21 Jan-23 Jan 115/105/095
  • 90 Day Mean 20 Jan 108

V. Geomagnetic A Indices

  • Observed Afr/Ap 19 Jan 031/062
  • Estimated Afr/Ap 20 Jan 012/015
  • Predicted Afr/Ap 21 Jan-23 Jan 015/025-015/020-010/020

VI. Geomagnetic Activity Probabilities 21 Jan-23 Jan

A. Middle Latitudes

  • Active 35/35/20
  • Minor storm 20/20/15
  • Major-severe storm 15/15/05

B. High Latitudes

  • Active 35/35/20
  • Minor storm 20/20/15
  • Major-severe storm 15/15/10

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