Last update issued on April 13, 2003 at 03:05 UTC.
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The geomagnetic field was quiet to unsettled on April 12. Solar wind speed ranged between 509 and 690 km/sec under the influence of a fairly benign high speed stream from coronal hole CH31.
Solar flux measured at 20h UTC on 2.8 GHz was 102.1. The planetary A
index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 8.8).
Three hour interval K indices: 32223222 (planetary), 32222222 (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 very low.
Region 10330 was mostly unchanged and quiet. A minor M class flare remains a possibility.
Region 10332 reemerged with several spots.
Region 10334 did not change much and still has a weak magnetic delta structure.
Spotted regions not yet numbered by SEC/NOAA:
[S137] A new region rotated into view at the southeast limb. Location at midnight: S20E68.
April 10 and 12: 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) will be in a geoeffective position on April 11-13.
Processed SOHO EIT 284 image at 19:06 UTC on April 12. Any black areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to unsettled on April 13 and most of April 14. A high speed stream from CH32 will likely reach Earth late on April 14 and dominate the solar wind until April 17 resulting in mostly unsettled to minor storm conditions. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is very poor and will likely remain so at least until April 19. Propagation along north-south paths is fair with fair expected for April 13-14 becoming fair to good on April 15-17. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay and Radio Vibración (Venezuela).]
|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|
classification was CAO
at midnight, area 0030
classification was DAO
|Total spot count:||30||29|
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||127.3 (1)||40.4 (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.