Last major update issued on July 26, 2006 at 03:10 UTC.
[Solar and
geomagnetic data - last month (updated daily)]
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[Solar cycles 21-23
(last update July 19, 2006)]
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[Graphical comparison
of cycles 21, 22 and 23 (last update July 19, 2006)]
[Graphical
comparison of cycles 2, 10, 13, 17, 20 and 23 (last update July 19, 2006)]
[Historical solar and
geomagnetic data charts 1954-2005 (last update March 3, 2006)]
[Archived reports (last update
July 9, 2006)]
The geomagnetic field was quiet to unsettled on July 25. Solar wind speed ranged between 337 and 349 km/s (all day average 346 km/s - increasing 2 km/s over the previous day) under the influence of a weak, low speed stream from CH232.
Solar flux measured at 20h UTC on 2.8 GHz was 75.5. 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: 32102112 (planetary), 33211212 (Boulder).
The background x-ray flux is at the class A3 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 10901 was quiet and stable.
July 23-25: No 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 (CH232) was in an Earth facing location on July 21-22. This coronal hole has decayed substantially over the past two solar rotations and is currently poorly defined. A coronal hole (CH233) in the northern hemisphere has poorly defined southward extensions that were in Earth facing locations on July 23-24. A recurrent trans equatorial coronal hole (CH234) has rotated into view and will likely be in an Earth facing location on July 29-30.
Processed SOHO/EIT 284 image at 19:06 UTC on July 25. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to unsettled on July 26-27 due to weak coronal hole effects and quiet on July 28-30.
| 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. Propagation on long distance northeast-southwest paths is poor to fair. Quite a few stations from North America were audible on the NW EWE, even Peruvians 1470 CPN Radio and 1499.93 Radio Santa Rosa were present. From North America the best signals were noted from 790 WSKO, 1130 WBBR, 1280 CFMB and 1510 WWZN. Bahamas on 1540 kHz was good at times.
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 |
|---|---|---|---|---|---|---|---|
| 10901 | 2006.07.22 | 6 | 10 | N06E28 | 0100 | DAO | classification was DSO at midnight |
| Total spot count: | 6 | 10 | |||||
| SSN: | 16 | 20 | |||||
| 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) |
| 2005.05 | 99.3 | 42.7 | 28.9 (-2.7) |
| 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 | (20.7 predicted, -2.3) |
| 2006.02 | 76.5 | 4.7 | (18.2 predicted, -2.5) |
| 2006.03 | 75.4 | 10.8 | (16.4 predicted, -1.8) |
| 2006.04 | 89.0 | 30.2 | (15.7 predicted, -0.7) |
| 2006.05 | 80.9 | 22.2 | (14.9 predicted, -0.8) |
| 2006.06 | 76.5 | 13.9 | (12.7 predicted, -2.2) |
| 2006.07 | 76.2 (1) | 19.0 (2) | (11.3 predicted, -1.4) |
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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