Viewing archive of Friday, 13 April 2001

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 2001 Apr 13 2200 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 103 Issued at 2200Z on 13 Apr 2001

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

Solar activity was very low. Region 9415 (S22W59) declined in size and number of spots during the period. This region still retains a beta-gamma-delta magnetic configuration and is still capable of producing M and X-class events. Region 9418 (N26W46) developed into a more magnetically complex beta-gamma configuration, however it produced very little activity today.
IB. Solar Activity Forecast
Solar activity is expected to be low to moderate. Region 9415 is still capable of producing another major flare before it rotates over the western limb.
IIA. Geophysical Activity Summary 12-2100Z to 13-2100Z
The geomagnetic field was at quiet to severe storm levels. A coronal mass ejection (CME), from an M2 flare on 11 April, impacted earth at 13/0735 UTC. A sudden impact of 19 nT was detected at the Boulder USGS magnetometer. The resulting disturbance caused major and severe geomagnetic storm conditions from 13/1900-2100 UTC, and minor to major storm conditions from 13/1200-1500 UTC. Conditions subsided to active levels for the remainder of the period. The greater than 10 MeV proton event ended at 13/1800 UTC. The polar cap absorption event (PCA) ended during the period.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to be unsettled to minor storming for the first two days of the period. These conditions will be the result of another impact at earth of a CME. This CME originated from an X2 event on 12 April. The expected arrival time is mid to late 14 April and at onset could cause major storm levels, with brief severe storm levels at high latitudes possible. Conditions should subside to quiet to active levels on the third day.
III. Event Probabilities 14 Apr to 16 Apr
Class M80%70%60%
Class X25%15%10%
IV. Penticton 10.7 cm Flux
  Observed       13 Apr 137
  Predicted   14 Apr-16 Apr  135/130/140
  90 Day Mean        13 Apr 166
V. Geomagnetic A Indices
  Observed Afr/Ap 12 Apr  029/038
  Estimated     Afr/Ap 13 Apr  025/035
  Predicted    Afr/Ap 14 Apr-16 Apr  050/055-025/030-015/015
VI. Geomagnetic Activity Probabilities 14 Apr to 16 Apr
A. Middle Latitudes
Minor storm40%15%10%
Major-severe storm30%10%06%
B. High Latitudes
Minor storm30%25%20%
Major-severe storm40%20%12%

All times in UTC

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