Viewing archive of Saturday, 20 April 2002

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 2002 Apr 20 2200 UTC
Prepared by the NOAA © SWPC and processed by SpaceWeatherLive.com

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 110 Issued at 2200Z on 20 Apr 2002

IA. Analysis of Solar Active Regions and Activity from 19-2100Z to 20-2100Z

Solar activity was low during the past 24 hours. Most of today's activity consisted of occasional C-class flares. The largest of these was a C4/Sf from Region 9912 at 1548 UTC. Region 9912 showed significant growth during the past 24 hours and is a D-type sunspot region. Region 9906 (S14W79) continues to be the largest group on the disk and is beginning to cross the west limb.
IB. Solar Activity Forecast
Solar activity is expected to be mostly low, but there is a chance for an isolated M-class event sometime during the next three days.
IIA. Geophysical Activity Summary 19-2100Z to 20-2100Z
The geomagnetic field was at active to major storm levels at mid-latitudes and was active to severe storm at high latitudes. The peak of the magnetic storm occurred from 0000-0900 UTC in association with strong transient solar wind flow. The level of geomagnetic activity weakened to mostly active during the last nine hours, consistent with the slow return of solar wind flow to nominal levels.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to be unsettled to active during the next 24 hours as the current disturbance subsides. Conditions should be mostly unsettled by the second day, and quiet to unsettled by the third day. There is a possibility for enhancement of greater than 2 MeV electrons during the next 24-36 hours due to the current high solar wind speeds.
III. Event Probabilities 21 Apr to 23 Apr
Class M35%30%25%
Class X05%05%05%
Proton05%05%05%
PCAFgreen
IV. Penticton 10.7 cm Flux
  Observed       20 Apr 177
  Predicted   21 Apr-23 Apr  170/170/170
  90 Day Mean        20 Apr 200
V. Geomagnetic A Indices
  Observed Afr/Ap 19 Apr  036/044
  Estimated     Afr/Ap 20 Apr  040/060
  Predicted    Afr/Ap 21 Apr-23 Apr  015/020-010/010-007/008
VI. Geomagnetic Activity Probabilities 21 Apr to 23 Apr
A. Middle Latitudes
Active45%25%20%
Minor storm20%20%20%
Major-severe storm15%05%05%
B. High Latitudes
Active45%30%25%
Minor storm20%20%20%
Major-severe storm20%10%10%

All times in UTC

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