Last major update issued on September 30, 2006 at 04:55 UTC.
geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update September 3, 2006)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update September 3, 2006)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update September 3, 2006)]
[Historical solar and geomagnetic data charts 1954-2005 (last update March 3, 2006)]
[Archived reports (last update September 8, 2006)]
The geomagnetic field was quiet on September 29. Solar wind speed ranged between 283 and 353 km/s (all day average 306 km/s - decreasing 56 km/s from the previous day). The high speed stream from CH241 arrived at ACE just before 03h UTC on September 30.
Solar flux measured at 20h UTC on 2.8 GHz was 76.5. The planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.3). Three hour interval K indices: 11100121 (planetary), 11221120 (Boulder).
The background x-ray flux is at the class A1 level.
At midnight there were 3 spotted regions on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day.
Region 10913 was quiet and stable.
Region 10914 developed slowly and was quiet.
New region 10915 emerged quickly in the southwest quadrant.
September 27-29: No obvious partly or fully Earth directed CMEs were detected in incomplete LASCO imagery. A full halo CME, probably from a region some days behind the east limb, was observed beginning early on September 26 in LASCO C3 images.
Coronal hole history (since late October 2002)
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago
A recurrent coronal hole (CH241) in the southern hemisphere was in an Earth facing position on September 25-27. CH241 has decayed considerably in the northern parts since the previous solar rotation. A small, poorly defined coronal hole in the northern hemisphere, maybe an extension or split from CH241, was in a potentially geoeffective position on September 27.
Processed SOHO/EIT 284 image at 14:06 UTC on September 29. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to active, maybe with minor storm intervals on September 30 and October 1 due to a high speed stream from CH241. Mostly quiet conditions are likely on October 2-5.
|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) Effects from a CME are likely to be observed at 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 poor. Propagation on long distance northeast-southwest paths is poor.
While Newfoundland stations were strong at 22h UTC, stations from the northeastern US had disappointing signals early in the night. Some of the best signals from the US were heard from the Florida stations on 1660, 1680 and 1700 kHz. A few stations from Brazil were audible at 21:50 UTC, notably on 1190 and 1470 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|
|10913||2006.09.28||2||2||S18E55||0070||HSX||classification was HAX at midnight|
|10914||2006.09.28||2||2||S07E62||0050||HRX||classification was HAX at midnight, area 0040|
|10915||2006.09.29||6||6||S06W46||0040||CSO||classification was CAO at midnight|
|Total spot count:||11||9|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2006.03||75.4||10.8||(17.1 predicted, -1.5)|
|2006.04||89.0||30.2||(16.4 predicted, -0.7)|
|2006.05||80.9||22.2||(15.9 predicted, -0.5)|
|2006.06||76.5||13.9||(14.1 predicted, -1.8)|
|2006.07||75.7||12.2||(12.4 predicted, -1.7)|
|2006.08||79.0||12.9||(11.9 predicted, -0.5)|
|2006.09||77.8 (1)||23.6 (2)||(11.9 predicted, -0.0)|
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% lower.
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.