Viewing archive of Thursday, 23 May 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 May 23 2200 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 143 Issued at 2200Z on 23 May 2002

IA. Analysis of Solar Active Regions and Activity from 22-2100Z to 23-2100Z

Solar activity was low. Region 9961 (S22E22) grew slowly as it produced a few minor C-class flares. The delta configuration is now apparent in the center of the group, as the leading spot simplified. Region 9957 (N10W19) decayed slightly but still retains a modest degree of magnetic complexity. Two new regions, 9966 (N10E34) and 9967 (N13E46) emerged.
IB. Solar Activity Forecast
Solar activity is expected to be moderate. Regions 9957 and 9961 are the most likely sites for isolated M-class flares. There continues to be a slight chance for a major flare event.
IIA. Geophysical Activity Summary 22-2100Z to 23-2100Z
The geomagnetic field varied from quiet to severe storm levels. The first of two shocks detected today passed ACE around 1000 UTC, as solar wind speeds increased from 400 to 600 km/s, causing a sudden impulse of 87 nT to be registered at Boulder at 1051 UTC. At approximately 1500 UTC, a second shock, boosting solar wind speeds to near 1,000 km/s for a short period, was seen at ACE. This perturbation caused a 26 nT sudden impulse at Boulder at 1545 UTC. This activity is thought to be an effect of the multiple CMEs observed to leave the sun yesterday. The greater than 10 MeV proton event that began at 22/1755 UTC attained a tentative maximum of 820 pfu at 23/1055 UTC and continues in progress.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to be at active to minor storm levels for the next 24 hours as the current disturbance wanes. No additional shocks or CMEs are expected. The field should continue to calm to unsettled conditions by the end of the interval. The greater than 10 MeV proton fluxes should continue to slowly decline.
III. Event Probabilities 24 May to 26 May
Class M50%50%50%
Class X10%10%10%
IV. Penticton 10.7 cm Flux
  Observed       23 May 180
  Predicted   24 May-26 May  175/170/170
  90 Day Mean        23 May 184
V. Geomagnetic A Indices
  Observed Afr/Ap 22 May  010/014
  Estimated     Afr/Ap 23 May  045/050
  Predicted    Afr/Ap 24 May-26 May  025/030-015/015-010/010
VI. Geomagnetic Activity Probabilities 24 May to 26 May
A. Middle Latitudes
Minor storm25%20%15%
Major-severe storm25%10%05%
B. High Latitudes
Minor storm25%30%20%
Major-severe storm40%20%15%

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