Viewing archive of Wednesday, 22 May 2002

Solar activity report

Report of Solar-Geophysical Activity 2002 May 22 2200 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 142 Issued at 2200Z on 22 May 2002

IA. Analysis of Solar Active Regions and Activity from 21-2100Z to 22-2100Z

Solar activity was moderate during the past 24 hours. An M1/2f event was produced by Region 9960 (N14E19) at 2139 UTC. The flare was associated with a CME from the northeast limb. This event was followed by a long duration C9/1f flare from Region 9948 (S21W84) which began at 21/2314 UTC, reached maximum at 22/0030 UTC, and ended at 22/0128 UTC. This event was associated with a CME from the southwest limb. Subsequent to this was another long-duration event, a C5/Sf (maximum time at 0354) from the eruption of a long, north-south filament just east of 9948 (near S22W53). This flare showed classic parallel ribbons in H-alpha and was associated with a very fast, spectacular looking full-halo CME. The plane-of-sky velocity was estimated to be about 1500 km/s. The appearance of the CME in the coronagraph data indicates a southwesterly direction of the leading edge. Region 9957 (N10W04) continues to dominate the disk in terms of area and magnetic field strengths but is decaying and has been quiet. Region 9961 (S22E34) retains its complexity from yesterday and is growing slowly, but was also quiet. Two new sunspot groups were assigned today: Region 9964 (S15E08) and Region 9965 (S10E62).
IB. Solar Activity Forecast
Solar activity is expected to be moderate during the next three days. The most likely sources for M-class events are 9957, 9960 (N14E19), and 9961. There continues to be a slight chance for a major flare or a proton producing flare.
IIA. Geophysical Activity Summary 21-2100Z to 22-2100Z
The geomagnetic field ranged from quiet to active levels. A weak shock passed the ACE spacecraft at about 21/2100 UTC and produced a sudden impulse at 21/2205 UTC which measured 27 nT on the Boulder magnetometer. The SI was followed by an isolated active period but conditions quickly dropped back to quiet to unsettled levels after 22/0000 UTC. An enhancement of greater than 10 MeV protons began around 0800 UTC. Flux levels rose slowly and finally crossed event threshold at 1755 UTC. The event remains in progress with current levels at about 46 PFU. It is likely that these particles were accelerated by the fast shock observed today on the southwest limb at 0350 UTC.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to be mostly unsettled with a chance for some active periods during the next 24 hours. The fast CME from the southwest limb associated with the erupting filament is expected to overtake the CME from the C9 flare, and the combined transient flow is expected to impact Earth sometime early on the 24th. Due to the apparent direction of the event, a direct hit is not expected, but it is likely that the eastern flank of the disturbance will impact the Earth. Activity levels are expected to be mostly active, but there is a chance for some isolated storm level activity. Conditions should subside to mostly unsettled with a few active periods by the third day. The greater than 10 MeV proton event is expected to end sometime in the next 24 hours.
III. Event Probabilities 23 May to 25 May
Class M55%55%55%
Class X10%10%10%
PCAFin progress
IV. Penticton 10.7 cm Flux
  Observed       22 May 181
  Predicted   23 May-25 May  180/175/170
  90 Day Mean        22 May 184
V. Geomagnetic A Indices
  Observed Afr/Ap 21 May  012/014
  Estimated     Afr/Ap 22 May  010/015
  Predicted    Afr/Ap 23 May-25 May  012/015-025/025-012/010
VI. Geomagnetic Activity Probabilities 23 May to 25 May
A. Middle Latitudes
Minor storm15%25%20%
Major-severe storm10%25%10%
B. High Latitudes
Minor storm20%25%30%
Major-severe storm15%40%20%

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