Last major update issued on September 23, 2004 at 04:05 UTC.
[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update September 2, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update September 2, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update September 2, 2004)]
[Historical solar and geomagnetic data charts 1954-2004 (last update August 28, 2004)]
[Archived reports (last update September 11, 2004)]
The geomagnetic field was quiet to minor storm on September 22. Solar wind speed ranged between 399 and 567 km/sec. A solar wind shock was observed at ACE near 06h UTC. Initially the interplanetary magnetic field was only occasionally southwards, however, after 10h UTC the IMF was southwards for sustained periods and caused a significant increase in geomagnetic activity.
Solar flux measured at 20h UTC on 2.8 GHz was 91.4. The planetary A
index was 16 (STAR Ap - based on the mean of three hour interval ap indices: 17.0).
Three hour interval K indices: 11335443 (planetary), 11335423 (Boulder).
The background x-ray flux is at the class B1 level.
At midnight there was 1 spotted region on the visible disk. The solar flare activity level was low. A total of 1 C class event was recorded during the day.
Region 10673 decayed slowly and quietly. Flare: impulsive C3.2 at 09:20 UTC.
September 20-22: No LASCO observations after September 20.
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
No obvious coronal holes are currently approaching geoeffective positions.
Processed SOHO/EIT 284 image at 19:06 UTC on September 10. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to active on September 24 and quiet to unsettled on September 25-27.
|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. When the high speed stream has arrived
the color changes to green.
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.
Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is very poor. Propagation along long distance north-south paths is poor to very poor. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant station tonight: none, a weak unidentified Spanish language station was heard. About the only station with a fair signal was WDHP on 1620 kHz.
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. SEC active region numbers in the table below and in the active region map above are the historic SEC/USAF numbers.
|Active region||Date numbered||SEC
|Location at midnight||Area||Classification||Comment|
classification was DSO
|Total spot count:||14||8|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2004.03||112.0||49.1||(47.0 predicted, -2.3)|
|2004.04||101.2||39.3||(44.8 predicted, -2.2)|
|2004.05||99.8||41.5||(41.5 predicted, -3.3)|
|2004.06||97.4||43.2||(38.6 predicted, -2.9)|
|2004.07||119.1||51.0||(36.8 predicted, -1.8)|
|2004.08||109.6||40.9||(35.4 predicted, -1.4)|
|2004.09||108.0 (1)||43.9 (2)||(34.2 predicted, -1.2)|
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 some of these solar data sources. All time references are to the UTC day. Comments and suggestions are always welcome.