Viewing archive of Wednesday, 17 July 2002

Solar activity report

Report of Solar-Geophysical Activity 2002 Jul 17 2200 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 198 Issued at 2200Z on 17 Jul 2002

IA. Analysis of Solar Active Regions and Activity from 16-2100Z to 17-2100Z

Solar activity was at high levels. Region 30 (N19W25) produced an M8/1b flare at 17/0713 UTC with an associated Type II radio burst. A CME was associated with this event but there does not appear to be an Earth directed component. Region 30 has shown slight decay in the leader spots but remains a large beta-gamma-delta spot group. As Region 36 (S09E51) rotates further into view it has developed into a moderately sized spot group with a beta-gamma-delta magnetic configuration. Activity from Region 36 so far has been C-Class events.
IB. Solar Activity Forecast
Solar activity is expected to be moderate. Region 30 and Region 36 are expected to produce M-class activity. They are also capable of producing a major flare during the period.
IIA. Geophysical Activity Summary 16-2100Z to 17-2100Z
The geomagnetic field has been quiet to active. A sudden impulse occurred at 17/1604 UTC and measured 18 nT on the San Juan magnetometer. Active conditions followed the sudden commencement. Greater than 10 MeV protons exceeded the 100 pfu threshold at 17/1250 UTC, reached a peak value of 234 pfu at 17/1600 UTC and ended at 17/1710 UTC. Greater than 10 MeV protons remain above the 10 pfu threshold as of this forecast issue. A PCA event began at 16/2215 UTC and reached a peak absorption 4.8 Db on the Thule 30 MHz riometer. Greater than 2 MeV electron at geo-synchronous orbit reached moderate levels.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to be quiet to active. Active conditions are possible early on day one due to the CME shock from the X3 event on 15 July. Isolated active conditions are possible on day three due to coronal hole effects and the possibility of a weak shock from the M8 event earlier today. The greater than 10 MeV proton event is expected to continue to decline and should end on day one of the forecast period. The PCA event in progress is expected to last until 19/0000 UTC. Maximum daytime absorption is expected to be about 6 Db, while maximum nighttime adsorption will be about 2 Db.
III. Event Probabilities 18 Jul to 20 Jul
Class M75%75%75%
Class X20%20%20%
PCAFin progress
IV. Penticton 10.7 cm Flux
  Observed       17 Jul 180
  Predicted   18 Jul-20 Jul  180/190/185
  90 Day Mean        17 Jul 161
V. Geomagnetic A Indices
  Observed Afr/Ap 16 Jul  009/011
  Estimated     Afr/Ap 17 Jul  020/020
  Predicted    Afr/Ap 18 Jul-20 Jul  015/015-010/012-012/020
VI. Geomagnetic Activity Probabilities 18 Jul to 20 Jul
A. Middle Latitudes
Minor storm20%10%05%
Major-severe storm10%01%01%
B. High Latitudes
Minor storm20%15%15%
Major-severe storm10%05%05%

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