Last update issued on September 12, 2003 at 03:30 UTC.
[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update September 1, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update September 1, 2003)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update September 1, 2003)]
[Historical solar and geomagnetic data charts 1954-2003 (last update July 23, 2003)]
[Archived reports (last update September 8, 2003)]
The geomagnetic field was quiet to minor storm on September 11. Solar wind speed ranged between 561 and 743 km/sec under the decreasing influence of a high speed stream from coronal hole CH55.
Solar flux measured at 20h UTC on 2.8 GHz was 96.7. The planetary A
index was 15 (STAR Ap - based on the mean of three hour interval ap indices: 16.5).
Three hour interval K indices: 45233333 (planetary), 45233332 (Boulder).
The background x-ray flux is at the class B2 level.
At midnight there were 2 spotted regions on the visible disk. Solar flare activity was low. A total of 2 C class events was recorded. Additionally a B8 long duration event peaked between 22 and 23h UTC and had a source near region S253.
Region 10456 decayed as several of the smaller spots disappeared. There is still some polarity intermixing. Flares: C1.0 at 14:12 and C1.2 at 14:54 UTC.
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. Location at midnight: S11W13.
September 9-11: No potentially 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 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 12-13.
Processed SOHO/EIT 284 image from 01:06 UTC on September 12. 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.
Long distance low frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor. Propagation along north-south paths is poor to fair. [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 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
|4||S11W13||0020||CSO||see region 10457|
|Total spot count:||35||25|
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||104.4 (1)||21.7 (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.