Last major update issued on August 26, 2007 at 04:10 UTC.
[Solar and
geomagnetic data - last month (updated daily)]
[Solar wind and
electron fluence charts (updated daily)
[Solar cycles 21-23
(last update July 23, 2007)]
[Solar cycles 1-20]
[Graphical comparison
of cycles 21, 22 and 23 (last update July 23, 2007)]
[Graphical
comparison of cycles 2, 10, 13, 17, 20 and 23 (last update July 23, 2007)]
[Historical solar and
geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports
(last update July 1, 2007)]
The geomagnetic field was quiet to unsettled on August 25. Solar wind speed ranged between 275 and 433 km/s (average speed was 334 km/s, increasing 59 km/s over the previous day). A fairly low speed stream from CH287 arrived after 08h UTC and caused a weaker than expected disturbance.
Solar flux measured at 20h UTC on 2.8 GHz was 71.5. The planetary A index was 8 (STAR Ap - based on the mean of three hour interval ap indices: 8.5). Three hour interval K indices: 21123232 (planetary), 22133233 (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 very low. No C class events were recorded during the day.
Region 10969 was quiet and stable.
August 23-25: No obvious fully or partly Earth directed CMEs were observed 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 (CH287) was in an Earth facing position on August 21-24. A recurrent coronal hole (CH288) in the southern hemisphere could rotate into an Earth facing position on August 29.
Processed STEREO 195 image at 23:45 UTC on August 25. The darkest areas on the solar disk are likely coronal holes.
Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor to fair. Propagation on long distance northeast-southwest paths is fair.
Monitoring remarks from a location near N58E06: August 24: Most TA frequencies had signals stronger than nearby European signals. Propagation to North America was the best ever I've recorded in August. One example is 1300 kHz which had WOOD dominating but with several others occasionally on top (WXRL, WJMO, two stations from Venezuela and one from Colombia). Radio Ciudad del Mar (Cuba) was noted on both 1340 and 1350 kHz one hour after LSR.
The geomagnetic field is expected to be quiet to unsettled on August 26-28 due to effects from CH287, occasional active intervals are possible. Quiet conditions are likely August 29-31.
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.
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 |
---|---|---|---|---|---|---|---|
10969 | 2007.08.21 | 4 | 2 | S05E22 | 0110 | CSO | classification was HAX at midnight |
Total spot count: | 4 | 2 | |||||
SSN: | 14 | 12 |
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) |
2006.06 | 76.5 | 13.9 | 16.3 (-1.0) |
2006.07 | 75.7 | 12.2 | 15.3 (-1.0) |
2006.08 | 79.0 | 12.9 | 15.6 (+0.3) |
2006.09 | 77.8 | 14.4 | 15.6 (+0.0) |
2006.10 | 74.3 | 10.4 | 14.2 (-1.4) |
2006.11 | 86.3 | 21.5 | 12.7 (-1.5) |
2006.12 | 84.5 | 13.6 | 12.1 (-0.6) |
2007.01 | 83.3 | 16.9 | 12.0 (-0.1) |
2007.02 | 77.7 | 10.6 | (11.6 predicted, -0.4) |
2007.03 | 72.2 | 4.8 | (11.1 predicted, -0.5) |
2007.04 | 72.4 | 3.7 | (10.8 predicted, -0.3) |
2007.05 | 74.4 | 11.7 | (10.4 predicted, -0.4) |
2007.06 | 73.7 | 12.0 | (10.3 predicted, -0.1) |
2007.07 | 71.6 | 10.0 | (10.5 predicted, +0.2) |
2007.08 | 68.9 (1) | 7.3 (2) | (11.0 predicted, +0.5) |
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.
[DX-Listeners' Club] |