Viewing archive of Thursday, 18 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 18 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 108 Issued at 2200Z on 18 Apr 2002IA. Analysis of Solar Active Regions and Activity from 17-2100Z to 18-2100Z Solar activity was low. Only C-class flares occurred
over the past 24 hours. Some of these flares did not have an obvious
source on the visible disk and may have originated from beyond the
limb. Region 9906 (S14W55) remains large and complex but has shown
some sunspot decay and magnetic simplification. New Regions 9911
(S13E23) and 9912 (N11E28) were numbered.
IB. Solar Activity Forecast
Solar activity is expected to be
moderate. M-class activity is expected in Region 9906. A major flare
in this region remains a possibility.
IIA. Geophysical Activity Summary 17-2100Z to 18-2100Z
The geomagnetic field ranged from quiet to severe storm levels in
response to the CME that impacted the Earth early yesterday. ACE
solar wind information suggests that this CME has passed. The
geomagnetic field is currently at active levels. Yesterday's greater
than 10 MeV proton event has ended: start 17/1530 UTC, maximum flux
(24 pfu) 17/1540 UTC, and end 18/0035 UTC.
IIB. Geophysical Activity Forecast
The geomagnetic field is
expected to be at unsettled to active levels through the end of 18
April UTC. Another CME is expected to impact the Earth early on 19
April UTC from an LDE/CME that occurred on 17 April. Minor to major
storm conditions are possible for the 24-48 hours following this
CME's arrival. Geomagnetic activity is expected to decline to
unsettled to active levels by the end of the 3-day forecast period.
Another greater than 10 MeV proton event is possible if Region 9906
generates a major flare.
III. Event Probabilities 19 Apr to 21 Apr
| Class M | 75% | 50% | 40% |
| Class X | 10% | 05% | 01% |
| Proton | 10% | 05% | 01% |
| PCAF | yellow | ||
IV. Penticton 10.7 cm Flux
Observed 18 Apr 188 Predicted 19 Apr-21 Apr 180/175/170 90 Day Mean 18 Apr 201
V. Geomagnetic A Indices
Observed Afr/Ap 17 Apr 027/041 Estimated Afr/Ap 18 Apr 045/050 Predicted Afr/Ap 19 Apr-21 Apr 040/040-030/050-012/020
VI. Geomagnetic Activity Probabilities 19 Apr to 21 Apr
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 50% | 50% | 30% |
| Minor storm | 30% | 20% | 10% |
| Major-severe storm | 20% | 10% | 05% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 35% | 50% | 30% |
| Minor storm | 40% | 30% | 20% |
| Major-severe storm | 25% | 15% | 05% |
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