Last major update issued on August 27, 2006 at 04:00 UTC.
geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update August 6, 2006)]
[Solar cycles 1-20]
[Graphical comparison 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 on August 26. Solar wind speed ranged between 329 and 345 km/s (all day average 341 km/s - decreasing 6 km/s from the previous day).
Solar flux measured at 20h UTC on 2.8 GHz was 75.8. The planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.3). Three hour interval K indices: 11100022 (planetary), 01101001 (Boulder).
The background x-ray flux is at the class A8 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 10905 was mostly unchanged in the trailing parts. The umbra within the large leading penumbra has fragmented into several smaller umbrae. Flare: C2.5 at 20:07 UTC.
August 24-26: No partly or fully Earth directed CMEs were detected in incomplete LASCO imagery. The C2.5 event late on August 26 in region 10905 may have been associated with an Earth directed CME.
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 (CH237) was in an Earth facing location on August 24-26. A recurrent coronal hole (CH238) in the southern hemisphere will likely rotate into an Earth facing position on August 28-30.
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 minor storm on August 27-29 due to effects from CH237 the first two days and from a possible Earth directed CME on August 29.
|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 fair. Greenland on 650 kHz was noted for the first time since early April. Several stations from the easternmost parts of North America were audible at fair signal levels. 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
|Location at midnight||Area||Classification||Comment|
|Total spot count:||11||9|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|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||79.6 (1)||17.5 (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.