Last major update issued on July 25, 2006 at 05:10 UTC.
geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update July 19, 2006)]
[Solar cycles 1-20]
[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 on July 24. Solar wind speed ranged between 335 and 351 km/s (all day average 344 km/s - increasing 25 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 77.0. The planetary A index
was 4 (STAR Ap - based on the mean of three hour interval ap
Three hour interval K indices: 10112212 (planetary), 20322212 (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 low. A single C class event was recorded during the day. This was a C1.1 flare at 14:46 UTC from an origin at or just behind the southeast limb.
Region 10901 decayed slowly and was mostly quiet.
July 22-24: 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.
Processed SOHO/EIT 284 image at 19:06 UTC on July 24. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to active on July 24-27 due to coronal hole effects and possibly a weak CME impact.
|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. Propagation on long distance northeast-southwest paths is fair to good. Lots of stations from Brazil, Uruugay and Argentina were heard, particularly above 1200 kHz. Frequencies like 1370, 1500, 1510, 1560 and 1570 kHz all had unusually clear signals from one or two stations.
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:||9||8|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|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)||18.5 (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.