Last major update issued on August 28, 2006 at 03:25 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 to minor storm on August 27. Solar wind speed ranged between 292 and 693 km/s (all day average 439 km/s - increasing 98 km/s over the previous day).
Solar flux measured at 20h UTC on 2.8 GHz was 78.6. The planetary A index was 18 (STAR Ap - based on the mean of three hour interval ap indices: 17.6). Three hour interval K indices: 21134543 (planetary), 11234533 (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 very low. No C class events were recorded during the day.
Region 10905 added many new spots as the leading penumbra fragmented. An area with negative polarity flux emerged at the northern edge of the leading positive polarity area. C flares are possible.
August 25 and 27: No partly or fully Earth directed CMEs were detected
in LASCO imagery.
August 26: The C2.5 event late on August 26 in region 10905 was associated with at least a partial halo CME. Most of the ejected material was observed over the southern limbs.
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 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 unsettled to active on August 28 and quiet to active on August 29 due to effects from CH237. A weak shock from the CME observed on August 26 is possible late on August 29, however, the presence of the current high speed stream could mask the arrival of the CME. Quiet to unsettled is likely on August 30-31 while a high speed stream from CH238 can cause unsettled to minor storm conditions on September 1-3.
|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 very poor. Weak audio was noted from 930 CJYQ and 1510 WWZN. Propagation on long distance northeast-southwest paths is poor to fair.
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|
classification was EAI at midnight
|Total spot count:||16||21|
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)||18.4 (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.