Viewing archive of Tuesday, 13 September 2005

Solar activity report

Report of Solar-Geophysical Activity 2005 Sep 13 2223 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 256 Issued at 2200Z on 13 Sep 2005

IA. Analysis of Solar Active Regions and Activity from 12-2100Z to 13-2100Z

Solar activity was high. Region 808 (S11E04) produced an M1.3 at 13/1121 UTC and an X1.5/3b at 13/1927 UTC. Strong centimetic radio bursts accompanied this flare including a 4900 sfu Tenflare and a 24,000 sfu burst on the 8800 MHz frequency. The X1.5 flare initially began as an impulsive flare; however, X-ray flux values began rising again resulting in a long duration event with a second peak above X1 levels. LASCO imagery shows a very bright and fast full halo CME with this event with a preliminary speed estimate of 1500 km/s. Region 808 underwent some slow decay over the last 24 hours, but still retains a strong beta-gamma-delta configuration.
IB. Solar Activity Forecast
Solar activity is expected to be moderate to high. Region 808 has potential for M and X-class activity.
IIA. Geophysical Activity Summary 12-2100Z to 13-2100Z
The geomagnetic field has been at unsettled to major storm levels. Storm conditions persisted through much of this period due to transient flow from the intense CME activity over the past several days. Conditions returned to predominantly unsettled levels by the end of the period. Solar wind speed at ACE remains elevated, but decreased from a high near 800 km/s to approximately 650 km/s by the end of the period. The greater than 10 MeV proton event that began on 08 September fell below the 10 pfu threshold today. The greater than 2 MeV electron flux at geosynchronous orbit reached high levels today.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to be unsettled to minor storm levels on 14 September. On 15 September, major to severe storm periods are possible due to the expected arrival of the CME associated with today's X1 flare. Conditions should subside to mostly unsettled to active levels by 16 September, with isolated minor storm periods possible.
III. Event Probabilities 14 Sep to 16 Sep
Class M 80%75%70%
Class X 50%40%30%
IV. Penticton 10.7 cm Flux
  Observed       13 Sep 114
  Predicted    14 Sep-16 Sep  115/110/110
  90 Day Mean        13 Sep 092
V. Geomagnetic A Indices
  Observed Afr/Ap 12 Sep  032/066
  Estimated     Afr/Ap 13 Sep  025/060
  Predicted     Afr/Ap 14 Sep-16 Sep  018/025-050/100-015/020
VI. Geomagnetic Activity Probabilities 14 Sep to 16 Sep
A. Middle Latitudes
Minor storm 20%20%15%
Major-severe storm 10%70%05%
B. High Latitudes
Minor storm 20%20%20%
Major-severe storm 15%70%10%

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