Last update issued on March 12, 2003 at 04:50 UTC.
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[Solar cycles 21-23 (last update March 3, 2003)]
[Solar cycles 1-20]
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The geomagnetic field was quiet to active on March 11. Solar wind speed ranged between 365 and 501 km/sec. A solar wind disturbance arrived at SOHO near 16h UTC but did not cause a significant change in geomagnetic activity.
Solar flux measured at 20h UTC on 2.8 GHz was 141.5. The planetary A
index was 13 (STAR Ap - based on the mean of three hour interval ap indices: 13.6).
Three hour interval K indices: 32433332 (planetary), 32333422 (Boulder).
The background x-ray flux is at the class B3 level.
At midnight there were 5 spotted regions on the visible disk. Solar flare activity was low. Only 1 C class event was recorded during the day.
Region 10296 decayed slowly and will soon rotate over the northwest limb
Region 10297 developed slowly and is approaching the southwest limb. Flare: C1.2 at 12:26 UTC.
Region 10300 developed several new spots and may be capable of C class flaring.
Region 10306 developed slowly with the huge penumbra expanding even more.
Region 10311 developed significantly and more than doubled its penumbral area. C class flares are possible.
March 9-11: No obviously geoeffective CMEs observed.
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 well defined, large, recurrent coronal hole (CH25) will rotate into a geoeffective position on March 11-17. This coronal hole has developed in the northwestern trans equatorial part but seems to have lost the long trans equatorial extension further east.
Processed SOHO EIT 284 image at 01:06 UTC on March 12. Any black areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to active on March 12 becoming unsettled to minor storm on March 13 as a high speed coronal hole stream begins to dominate the solar wind. Unsettled to active conditions will then be likely until March 20. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is poor, propagation along north-south paths is fair. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay with a stronger than usual signal]
|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|
SEC has this as
the spots belong to
10297, this region
should be deleted
classification was EKO
at midnight. STAR
spot count includes
these are the trailing
negative polarity spots
of region 10306
area was 0120 at
|Total spot count:||52||47|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2002.09||175.8||109.6||(94.7 predicted, -4.0)|
|2002.10||167.0||97.5||(91.2 predicted, -3.5)|
|2002.11||168.7||95.0||(86.0 predicted, -5.2)|
|2002.12||157.2||81.6||(81.6 predicted, -4.4)|
|2003.01||144.0||79.5||(78.6 predicted, -3.0)|
|2003.02||124.5||46.2||(73.6 predicted, -5.0)|
|2003.03||145.6 (1)||53.8 (2)||(67.9 predicted, -5.7)|
1) Running average based on the daily 20:00 UT observed solar flux value at 2800
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.