Last update issued on September 13, 2003 at 03:25 UTC.
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[Solar cycles 21-23 (last update September 1, 2003)]
[Solar cycles 1-20]
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[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update September 1, 2003)]
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[Archived reports (last update September 8, 2003)]
The geomagnetic field was quiet to unsettled on September 12. Solar wind speed ranged between 551 and 630 km/sec.
Solar flux measured at 20h UTC on 2.8 GHz was 94.4. The planetary A
index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 12.4).
Three hour interval K indices: 33333322 (planetary), 33222211 (Boulder).
The background x-ray flux is at the class B2 level.
At midnight there were 3 spotted regions on the visible disk. Solar flare activity was very low.
Region 10456 developed slowly as more spots added penumbra. Polarities are mixed and the region could produce at least C class flares.
Spotted regions not numbered by NOAA/SEC:
[S253] A new bipolar region emerged in the southeast quadrant on September 10 due east of region 10457. The region was mostly unchanged on September 11 and decayed on September 12. Location at midnight: S12W26.
[S254] A new region emerged in the southwest quadrant on September 12, just northeast of region S253. Location at midnight: S08W20.
September 10-11: No potentially geoeffective CMEs observed.
September 12: A full halo CME was observed early in the day. The CME was best defined over the south pole and was faint over the northern limbs. The source of this CME is likely the B8 event which occurred late on September 11 when a filament erupted just south of region S253. The CME is likely to reach Earth early on September 15.
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 fairly small coronal hole (CH56) in the northern hemisphere will likely rotate into a geoeffective position on September 13. A recurrent coronal hole (CH57) in the southern hemisphere and with a trans equatorial extension will rotate into a geoeffective position on September 15-17. A coronal hole (CH58) emerged in the southeast quadrant on September 11 and will be in a geoeffective position on September 13.
Processed SOHO/EIT 284 image from 01:06 UTC on September 13. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to unsettled until September 14. High speed streams from coronal holes CH58, CH56 and CH57 will likely cause unsettled to active conditions on September 15-17 and unsettled to minor storm on September 18-20. The CME associated with a filament eruption late on September 11 could cause unsettled to active geomagnetic conditions early on September 15.
Long distance low frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor to fair. Propagation along north-south paths is fair. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: 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 NOAA/SEC. 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|
SECs spots belong
to region S253
|1||S12W26||0010||AXX||see region 10457|
|Total spot count:||38||27|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2003.03||131.4||61.1||(74.2 predicted, -4.3)|
|2003.04||126.4||60.0||(69.3 predicted, -4.9)|
|2003.05||115.7||55.2||(64.4 predicted, -4.9)|
|2003.06||129.3||77.4||(60.4 predicted, -4.0)|
|2003.07||127.7||85.0||(56.9 predicted, -3.5)|
|2003.08||122.1||72.7||(53.9 predicted, -3.0)|
|2003.09||103.5 (1)||23.7 (2)||(51.9 predicted, -2.0)|
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 (NOAA/SEC) sunspot number. The official international sunspot number is typically 30-50% less.
This report has been prepared by Jan Alvestad. It is based partly on my own observations and analysis, and partly on data from sources noted in solar links. All time references are to the UTC day. Comments and suggestions are always welcome.