Last major update issued on September 28, 2004 at 03:05 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 27, 2004)]
The geomagnetic field was quiet to slightly unsettled on September 27. Solar wind speed ranged between 327 and 385 km/sec. A low speed flow from coronal hole CH115 was observed starting at ACE near 06h UTC and slowly increased in speed.
Solar flux measured at 20h UTC on 2.8 GHz was 89.8. The planetary A
index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 6.4).
Three hour interval K indices: 11012231 (planetary), 10012321 (Boulder).
The background x-ray flux is at the class A7 level.
At midnight there was 1 spotted region on the visible disk. The solar flare activity level was very low. No C class events were recorded during the day.
Region 10675 was quiet and stable.
September 25-27: No obviously earth directed CMEs observed in limited LASCO data set.
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. A poorly defined coronal hole (CH115) in the northern hemisphere was in a geoeffective position on September 24-25.
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 unsettled on September 28-30 with a chance of active intervals on September 28 due to a coronal hole flow.
|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 was good to very good early in the night, however, conditions have deteriorated over the last hour to fair to good. Propagation along long distance north-south paths is poor. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant stations tonight: Radio Vibración (Venezuela) and WLAM Lewiston ME. On other frequencies a large number of stations from the eastern parts of North America were noted with unusually strong signals.
Local sunrise propagation on September 27 was good to very good towards eastern North America with some stations having very strong signals, Radio Disney New York on 1560 kHz was observed with a better than S9+20dB signal (no amplification used).
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|
|10673||2004.09.15||1||S15W88||0200||HSX||rotated out of view|
|Total spot count:||2||1|
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||104.6 (1)||47.3 (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.