Last major update issued on August 26, 2004 at 03:40 UTC.
[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update August 2, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update August 2, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update August 2, 2004)]
[Historical solar and geomagnetic data charts 1954-2004 (last update April 28, 2004)]
[Archived reports (last update August 25, 2004)]
The geomagnetic field was quiet to slightly unsettled on August 25. Solar wind speed ranged between 296 and 363 km/sec. A weak coronal hole flow from CH110 was probably the cause of an increase in solar wind speed after 08h UTC.
Solar flux measured at 20h UTC on 2.8 GHz was 100.4. The planetary A
index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 7.6).
Three hour interval K indices: 12123222 (planetary), 02222321 (Boulder).
The background x-ray flux is at the class B1-B2 level.
At midnight there were 3 spotted regions on the visible disk. The solar flare activity level was low. A single C class event was recorded during the day.
Region 10661 rotated mostly out of view at the northwest limb.
Region 10663 had small trailing spots emerging in the eastern negative polarity area. Flare: C1.3 at 05:21 UTC.
Region 10664 decayed with penumbra disappearing from the trailing spots. New intermediate spots emerged.
August 23-25: No obviously Earth directed CMEs were observed.
Coronal hole history (since late October 2002)
Compare today's report with the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago
No obvious coronal holes are currently at or near geoeffective positions.
Processed SOHO/EIT 284 image at 01:06 UTC on August 26. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be mostly quiet on August 26-29.
|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) Material from a CME is likely to impact 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 and improving. Propagation along long distance north-south paths is poor to very poor. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant stations tonight: WLAM Lewiston ME and Radio Vibración (Venezuela). Propagation was best towards North America with a number of stations observed throughout the MW band. Greenland was noted on 570.05 kHz fairly good at 03h UTC, a sign that the northwesterly paths are opening. Otherwise stations from Newfoundland and the New York area had the best signals, however, signal levels are still fairly low. Yesterday morning after local sunrise there was a brief opening towards Argentina with Radio Brigadier Lopez on 1150 kHz the most interesting station.
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 HAX
at midnight, area 0200
classification was CAO
classification was CAO
|Total spot count:||30||28|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2004.02||107.0||45.8||(49.1 predicted, -2.9)|
|2004.03||112.0||49.1||(46.5 predicted, -2.6)|
|2004.04||101.2||39.3||(44.3 predicted, -2.2)|
|2004.05||99.8||41.5||(41.0 predicted, -3.3)|
|2004.06||97.4||43.2||(38.2 predicted, -2.8)|
|2004.07||119.1||51.0||(36.3 predicted, -1.9)|
|2004.08||114.3 (1)||63.7 (2)||(34.9 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% less.
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.