Last update issued on April 14, 2003 at 01:50 UTC.
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[Solar cycles 21-23 (last update April 2, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update April 2, 2003)]
[Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update April 2, 2003)]
[Historical solar and geomagnetic data charts 1954-2003 (last update April 13, 2003)]
[Archived reports (last update April 7, 2003)]
The geomagnetic field was quiet to unsettled on April 13. Solar wind speed ranged between 444 and 561 km/sec. The expected high speed stream from coronal hole CH32 appears to be in progress early on April 14.
Solar flux measured at 20h UTC on 2.8 GHz was 102.4. The planetary A
index was 10 (STAR Ap - based on the mean of three hour interval ap indices: 10.9).
Three hour interval K indices: 33223222 (planetary), 33223322 (Boulder).
The background x-ray flux is at the class B1 level.
At midnight there were 4 spotted regions on the visible disk. Solar flare activity was low. Only 1 C class event was recorded during the day.
Region 10330 decayed slowly and was mostly quiet. Flare:
C2.7 at 08:54 UTC.
Region 10332 was mostly unchanged and quiet.
Region 10334 decayed slowly and quietly.
Region 10335 rotated into view on April 12 and was numbered the next day.
April 12-13: No obviously geoeffective CMEs observed.
April 11: A long duration class B3 event beginning just after 13h UTC and peaking near 14h UTC was associated with an erupting filament in the southwest quadrant near the center of the visible disk (and between coronal holes CH31 and CH32). A small CME may have been associated with this event.
Coronal hole history (since late October 2002)
Compare today's report with the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago
A huge trans equatorial southern hemisphere coronal hole (CH32) was in a geoeffective position on April 11-13.
Processed SOHO EIT 284 image at 13:06 UTC on April 13. Any black areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to minor storm on April 14 and unsettled to minor storm on April 15-16 due to a high speed stream from coronal hole CH32. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is likely to remain very poor until at least April 19. Propagation along north-south paths is poor to fair with fair or fair to good expected for April 15-18. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay.]
|Coronal holes (1)||Coronal mass ejections (2)||M and X class flares (3)|
1) Effects from a coronal hole could reach Earth within the next 5 days.
2) Material from a CME is likely to impact Earth within 96 hours.
3) There is a possibility of either M or X class flares within the next 48 hours.
Green: 0-20% probability, Yellow: 20-60% probability, Red: 60-100% probability.
Compare to the previous day's image.
Data for all numbered solar regions according to the Solar Region Summary provided by SEC/NOAA. Comments are my own, as is the STAR spot count (spots observed at or inside a few hours before midnight) and data for regions not numbered by SEC or where SEC has observed no spots.
|Solar region||Date numbered||SEC
|Location at midnight||Area||Classification||Comment|
formerly region S137
classification was CAO
|Total spot count:||21||20|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2002.10||167.0||97.5||(91.0 predicted, -3.6)|
|2002.11||168.7||95.0||(85.7 predicted, -5.3)|
|2002.12||157.2||81.6||(81.3 predicted, -4.4)|
|2003.01||144.0||79.5||(78.3 predicted, -3.0)|
|2003.02||124.5||46.2||(73.3 predicted, -5.0)|
|2003.03||131.4||61.5||(67.6 predicted, -5.7)|
|2003.04||125.4 (1)||42.5 (2)||(62.7 predicted, -4.9)|
1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz.
2) Unofficial, accumulated value based on the Boulder (SEC/NOAA) sunspot number. The official international sunspot number is typically 25-45% less.
This report has been prepared by Jan Alvestad. It is based partly on my own observations and interpretations, and partly on data from sources noted in solar links. All time references are to the UTC day. Comments and suggestions are always welcome.