Last major update issued on August 24, 2004 at 03:45 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 10, 2004)]
The geomagnetic field was quiet to unsettled on August 23. Solar wind speed ranged between 362 and 452 km/sec.
Solar flux measured at 20h UTC on 2.8 GHz was 109.5. The planetary A
index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 7.9).
Three hour interval K indices: 22222322 (planetary), 23223322 (Boulder).
The background x-ray flux is at the class B1 level.
At midnight there were 4 spotted regions on the visible disk. The solar flare activity level was very low. No C class events were recorded during the day.
Region 10661 decayed slowly and quietly.
Region 10662 decayed further and has only a single small spot left.
Region 10663 decayed slowly with penumbra disappearing from the trailing spots.
Region 10664 lost some intermediate spots, however, new spots emerged both in the leading and trailing spot sections.
August 21-23: 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
The northernmost extension of a coronal hole (CH110) in the southern hemisphere was likely in a geoeffective position on August 21.
Processed SOHO/EIT 284 image at 01:06 UTC on August 24. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to active on August 24-25 due to a weak coronal hole flow and quiet to unsettled on August 26-27.
|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 poor to fair. Propagation along long distance north-south paths is poor. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant stations tonight: Radio Vibración (Venezuela) with a weak signal. Stations from Venezuela were observed on a number of other frequencies including 970, 1110, 1140, 1420 and 1430 kHz. From North America signals were heard on 20-30 frequencies, mostly with stations from Newfoundland, Nova Scotia and the New York area.
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 CAO
at midnight, are 0320
classification was AXX
classification was EAO
|Total spot count:||43||30|
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||115.3 (1)||60.0 (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.