Last major update issued on September 23, 2006 at 03:30 UTC.
[Solar and
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 22. Solar wind speed ranged between 288 and 310 km/s (all day average 295 km/s - decreasing 12 km/s from the previous day).
Solar flux measured at 20h UTC on 2.8 GHz was 72.3. The planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.1). Three hour interval K indices: 01001221 (planetary), 11011220 (Boulder).
The background x-ray flux is below the class A1 level.
At midnight there was 1 spotted region on the visible solar disk. The solar flare activity level was low. A single C class event was recorded during the day.
Region 10910 developed quickly early in the day adding many small spots. The region was unstable for most of the day and decayed again during the latter half. Flare: C1.2 beginning at 23:50 UTC and peaking at 00:02 UTC on September 23.
September 20-22: No obvious partly or fully Earth directed CMEs were detected in 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 (CH240) was in an Earth facing position on September 20-21. A recurrent coronal hole (CH241) in the southern hemisphere will likely be in an Earth facing position on September 26-27.
Processed SOHO/EIT 284 image at 19:06 UTC on September 22. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to minor storm on September 23-24 due to a high speed stream from CH240. Quiet to unsettled is likely on September 25 becoming mostly quiet on September 26-28. Quiet to minor storm conditions are again likely on September 29-30 due to a high speed stream from CH241.
| 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 good. Many stations from the eastern parts of North America had fair to strong signals at night. During the hour after LSR on September 22 propagation was excellent to Colombia (for instance 820 Caracol Radio Calí). Propagation on long distance northeast-southwest paths is 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 spot count |
STAR spot count |
Location at midnight | Area | Classification | Comment |
|---|---|---|---|---|---|---|---|
| 10910 | 2006.09.18 | 7 | 9 | S10W04 | 0050 | CSI | classification was CAI at midnight beta-gamma |
| Total spot count: | 7 | 9 | |||||
| SSN: | 17 | 19 | |||||
| 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) |
| 2005.07 | 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 | 18.6 (-2.2) |
| 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 | 79.7 (1) | 18.7 (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.
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