Viewing archive of Tuesday, 10 April 2001

Solar activity report

Report of Solar-Geophysical Activity 2001 Apr 10 2200 UTC
Prepared by the NOAA © SWPC and processed by SpaceWeatherLive.com

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 100 Issued at 2200Z on 10 Apr 2001

IA. Analysis of Solar Active Regions and Activity from 09-2100Z to 10-2100Z

Solar activity remained at high levels. Region 9415 (S23W19) produced a long-duration X2/3b parallel-ribbon flare at 10/0526 UTC. This flare was associated with a 4000 SFU Tenflare, Type II and IV radio sweeps, a 14-degree filament disappearance, and a fast full-halo CME. Region 9415 showed decay in its trailer spots, but maintained a strong magnetic delta configuration in its leader portion, where a minor increase in spots was noted. Minor growth occurred in Region 9417 (S08W39). It produced a C6/Sf at 10/1451 UTC. Minor growth was also observed in Region 9425 (S25W49). The remaining regions were simply-structured and stable. No new regions were assigned.
IB. Solar Activity Forecast
Solar activity is expected to be at moderate to high levels. Region 9415 is expected to produce another major flare during the period.
IIA. Geophysical Activity Summary 09-2100Z to 10-2100Z
Geomagnetic field activity ranged from quiet to active levels. A greater than 10 MeV proton event followed today's X2/3b flare. It began at 10/0850 UTC and was in progress as the period ended. The greater than 10 MeV proton flux was near 100 PFU at the close of the period and gradually increasing. A greater than 100 MeV proton flux enhancement was also associated with the X2/3b flare. A polar cap absorption (PCA) event began around 10/1200 UTC and continued as the period ended. Thus far, maximum absorption associated with the PCA event has been estimated at 8.5 dB. The greater than 2 MeV electron flux reached high levels during the period.
IIB. Geophysical Activity Forecast
A major geomagnetic storm is expected during 11 - 12 April in response to halo-CMEs observed on 09 - 10 April. Active to major storm levels are expected during this disturbance with brief severe storm levels possible at high latitudes. Unsettled to minor storm levels are expected on 13 April as the storm subsides. The greater than 10 MeV proton event is expected to continue through most of the period. The PCA event is expected to end during the latter half of the period. The greater than 2 MeV electron flux is expected to be at moderate to high levels during the period.
III. Event Probabilities 11 Apr to 13 Apr
Class M 80%80%80%
Class X 25%25%25%
Proton90%80%25%
PCAFIn Progress
IV. Penticton 10.7 cm Flux
  Observed       10 Apr 170
  Predicted    11 Apr-13 Apr  165/165/160
  90 Day Mean        10 Apr 167
V. Geomagnetic A Indices
  Observed Afr/Ap 09 Apr  017/019
  Estimated     Afr/Ap 10 Apr  013/009
  Predicted     Afr/Ap 11 Apr-13 Apr  050/040-050/090-020/030
VI. Geomagnetic Activity Probabilities 11 Apr to 13 Apr
A. Middle Latitudes
Active15%15%35%
Minor storm 25%25%15%
Major-severe storm 45%45%10%
B. High Latitudes
Active15%25%35%
Minor storm 30%30%20%
Major-severe storm 50%35%15%

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