Last major update issued on September 11, 2006 at 04:25 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 10. Solar wind speed ranged between 338 and 367 km/s (all day average 347 km/s - increasing 1 km/s over the previous day). A weak disturbance was in progress most of the day and early on September 11.
Solar flux measured at 20h UTC on 2.8 GHz was 87.3. The planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 6.0). Three hour interval K indices: 12111212 (planetary), 03222212 (Boulder).
The background x-ray flux is at the class A6 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 10907 developed slightly and was quiet.
Region 10908 decayed slowly and was quiet.
Region 10909 decayed fairly quickly in the leading spot section. A patch of negative polarity flux emerged in the southern part of the trailing spot section.
September 9-10: No obvious partly or fully Earth directed CMEs were detected
in incomplete LASCO imagery.
September 8: While there were mayn data gaps some of the LASCO images from early in the day and around noon displays CMEs in progress. Based on the scant evidence available it is hard to tell if these CMEs had a frontsided origin.
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 (CH239) in the southern hemisphere will likely rotate into an Earth facing position on September 14.
Processed SOHO/EIT 284 image at 19:08 UTC on August 18. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be mostly quiet on September 11-16. There is a slight chance of CME effects reaching Earth on September 11. Weak coronal hole effects are possible on September 17.
|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 fair to occasionally good. Pre sunrise conditions is favoring stations from the northeast US with strong signals from a number of stations. 790 WSKO, 1290 WRNI and 1370 WDEA were all good while most of the 50 kW New York and Boston stations had excellent signals. Propagation on long distance northeast-southwest paths is very poor.
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|
|10907||2006.09.05||5||4||S12W20||0010||BXO||classification was CRO at midnight|
|10909||2006.09.06||10||4||S11W30||0080||DRO||area was 0030 at midnight|
|Total spot count:||20||10|
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||81.9 (1)||10.6 (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.