Last major update issued on August 28, 2004 at 03:10 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 August 28, 2004)]
[Archived reports (last update August 25, 2004)]
The geomagnetic field was quiet to unsettled on August 27. Solar wind speed ranged between 377 and 510 km/sec.
Solar flux measured at 20h UTC on 2.8 GHz was 90.5. The planetary A
index was 8 (STAR Ap - based on the mean of three hour interval ap indices: 8.8).
Three hour interval K indices: 31122323 (planetary), 21212222 (Boulder).
The background x-ray flux is at the class A7 level.
At midnight there were 2 spotted regions on the visible disk. The solar flare activity level was very low. No C class events were recorded during the day.
Region 10663 developed slowly in the trailing spot section while slow decay was observed in the leading spot section.
Region 10664 decayed slowly and quietly.
August 25-27: 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
A poorly defined coronal hole (CH111) in the northern hemisphere could rotate into a geoeffective position on August 27-29.
Processed SOHO/EIT 284 image at 13:06 UTC on August 27. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be mostly quiet on August 28-29. A weak coronal hole related disturbance could reach Earth on August 30-31 and cause unsettled to active intervals.
|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 to good. 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: Radio Vibración (Venezuela) and WLAM Lewiston ME. Apart from the Venezuelan stations Marabina 1420 and Radio Dos Mil 1500 kHz, no other stations from South America were noted. Propagation again favored the northeastern parts of the USA and Canada with stations heard on many frequencies after midnight UTC. Greenland was noted on 570.05, today with the parallel 650 kHz having a better signal.
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:||13||14|
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||112.8 (1)||66.2 (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.