Last major update issued on September 3, 2006 at 06:35 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 August 6, 2006)]
The geomagnetic field was quiet to unsettled on September 2. Solar wind speed ranged between 360 and 543 km/s (all day average 443 km/s - increasing 81 km/s over the previous day) under the influence of a weaker than expected high speed stream from CH238.
Solar flux measured at 20h UTC on 2.8 GHz was 75.6. The planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 7.4). Three hour interval K indices: 31111133 (planetary), 31121122 (Boulder).
The background x-ray flux is at the class A5 level.
At midnight there were the visible solar disk was spotless. The solar flare activity level was very low. No C class events were recorded during the day.
August 31 - September 2: No partly or fully Earth directed CMEs were detected in incomplete LASCO imagery.
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 trans equatorial coronal hole (CH238) was in an Earth facing position on August 29-31. Another coronal hole in thre southern hemisphere was probably too far south on September 3 (when it rotated across the central meridian) to become geoeffective.
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 quiet to active on September 3 due to a high speed stream from CH238 and quiet to unsettled on September 4. Mostly quiet is likely on September 5-8.
|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 generally poor. Weak to fair signals were noted from a number of stations along the east coast of Canada and the USA. Longer distance propagation to Colombia was quite good with many stations audible during the hour after LSR. For instance a station on 1170 kHz had fairly strong peaks but remained unidentified (although it was obviously from Colombia). Propagation on long distance northeast-southwest paths is poor to 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|
|10905||2006.08.20||1||S08W96||0030||AXX||rotated out of view|
|10906||2006.08.31||6||S09W78||0090||BXO||rotated out of view|
|Total spot count:||7||0|
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||76.3 (1)||2.0 (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.