Last major update issued on September 1, 2006 at 04:35 UTC.
[Solar and
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(last update August 6, 2006)]
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of cycles 21, 22 and 23 (last update August 6, 2006)]
[Graphical
comparison of cycles 2, 10, 13, 17, 20 and 23 (last update August 6, 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 August 31. Solar wind speed ranged between 369 and 468 km/s (all day average 410 km/s - decreasing 86 km/s from the previous day).
Solar flux measured at 17h UTC on 2.8 GHz was 76.5 (the measurement at 20h UTC was enhanced by a long duration B class event). The planetary A index was 8 (STAR Ap - based on the mean of three hour interval ap indices: 8.1). Three hour interval K indices: 11211333 (planetary), 12322222 (Boulder).
The background x-ray flux is at the class A7 level.
At midnight there were 2 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 10905 decayed further and was quiet.
New region 10906 emerged in the southwest quadrant on August 30 and was
numbered by NOAA/SEC the following day. The region developed slowly on August 31
and could produce C class flares.
August 29-31: 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.
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 unsettled initially on September 1. Late in the day or early on September 2 a high speed stream from CH238 can cause unsettled to major storm conditions until September 3.
| 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 to occasionally fair. Several fair to strong signals were noted from stations on Newfoundland and from the northeastern USA. Perú was represented by 1470 CPN Radio and 1500 Radio Santa Rosa. Several stations from Cuba had fair signals. Propagation on long distance northeast-southwest paths is poor to fair with the best signals from Uruguay and Argentina.
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 spot count |
STAR spot count |
Location at midnight | Area | Classification | Comment |
|---|---|---|---|---|---|---|---|
| 10905 | 2006.08.20 | 7 | 5 | S08W68 | 0100 | DSO | classification was HAX at midnight, area 0060 |
| 10906 | 2006.08.31 | 12 | 12 | S09W52 | 0100 | CAO | formerly region S673 classification was DAI at midnight, area 0110 |
| Total spot count: | 19 | 17 | |||||
| SSN: | 39 | 37 | |||||
| Month | Average solar flux at Earth |
International sunspot number | Smoothed sunspot number |
|---|---|---|---|
| 2000.04 | 184.2 | 125.5 | 120.8 cycle 23 sunspot max. |
| 2000.07 | 202.3 | 170.1 | 119.8 |
| 2001.12 | 235.1 | 132.2 | 114.6 (-0.9) |
| 2005.06 | 93.7 | 39.3 | 28.8 (-0.1) |
| 2005.07 | 96.4 | 40.1 | 29.1 (+0.3) |
| 2005.08 | 90.5 | 36.4 | 27.4 (-1.7) |
| 2005.09 | 91.1 | 21.9 | 25.8 (-1.6) |
| 2005.10 | 77.0 | 8.5 | 25.5 (-0.3) |
| 2005.11 | 86.3 | 18.0 | 24.9 (-0.6) |
| 2005.12 | 90.7 | 41.2 | 23.0 (-1.9) |
| 2006.01 | 83.4 | 15.4 | 20.8 (-2.2) |
| 2006.02 | 76.5 | 4.7 | (18.4 predicted, -2.4) |
| 2006.03 | 75.4 | 10.8 | (16.6 predicted, -1.8) |
| 2006.04 | 89.0 | 30.2 | (15.9 predicted, -0.7) |
| 2006.05 | 80.9 | 22.2 | (15.1 predicted, -0.8) |
| 2006.06 | 76.5 | 13.9 | (12.9 predicted, -2.2) |
| 2006.07 | 75.7 | 12.2 | (11.4 predicted, -1.5) |
| 2006.08 | 79.0 (1) | 22.8 (2) | (11.4 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.
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