Last major update issued on August 17, 2006 at 05:00 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 inactive to very quiet on August 16. Solar wind speed ranged between 271 and 342 km/s (all day average 294 km/s - increasing 7 km/s over the previous day).
Solar flux measured at 23h UTC on 2.8 GHz was 94.0 (measurements at 17 and
20h UTC were strongly influenced by a very long duration C class event, even the
23h value is slightly enhanced). The planetary A index
was 3 (STAR Ap - based on the mean of three hour interval ap
Three hour interval K indices: 11011011 (planetary), 11111122 (Boulder).
The background x-ray flux is at the class B1 level.
At midnight there was 1 spotted region on the visible solar disk. The solar flare activity level was low. A total of 3 C class events was recorded during the day.
Region 10904 decayed slowly and could produce further long duration events. Flares: C3.6 very long duration event (associated with a strong type IV radio sweep) peaking at 16:17 UTC, C3.5 at 18:47 and C1.0 at 23:17 UTC
August 14-15: No partly or fully Earth directed CMEs were detected in
August 16: A large Earth directed CME was observed in LASCO images after the LDE in region 10904 during the afternoon.
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 small coronal hole in the northern hemisphere could reach an Earth facing position on August 17-18.
Processed SOHO/EIT 284 image at 01:08 UTC on August 17. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be mostly quiet August 17-18 and quiet to major storm on August 19-20. The large full halo CME observed on August 16 will likely reach Earth near noon on August 19 and cause active to major storm conditions up to 12-24 hours after its arrival.
|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 to good. Many stations from North America were audible. While the best propagation was to the east coast, stations as far inland as Chicago could be heard. The New York stations on 880, 1050 and 1130 all had excellent signals. Propagation on long distance northeast-southwest paths is very 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:||19||19|
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||77.6 (1)||10.6 (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.