Last major update issued on August 10, 2004 at 04:15 UTC.
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[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 1, 2004)]
The geomagnetic field was quiet to active on August 9. Solar wind speed ranged between 345 and 409. The compressed solar wind zone ahead of a high speed stream from coronal hole CH108 arrived between 15 and 21h UTC. This was accompanied by a moderately strong southward swing of the interplanetary magnetic field.
Solar flux measured at 20h UTC on 2.8 GHz was 113.9. The planetary A
index was 13 (STAR Ap - based on the mean of three hour interval ap indices: 14.4).
Three hour interval K indices: 22432334 (planetary), 22432333 (Boulder).
The background x-ray flux is at the class B4 level.
At midnight there were 5 spotted regions on the visible disk. The solar flare activity level was low. A total of 14 C class events were recorded during the day.
Region 10655 decayed slowly and quietly.
Region 10656 developed quickly in the trailing and central parts. The central penumbra has one or magnetic delta structures. An M class flare is possible. Flares: C5.1 at 00:30, C3.0/1N at 01:13, C2.4 at 07:33, C4.8 at 08:08, C1.1 at 08:40, C1.7 at 11:06, C3.3 at 13:35, C1.1 at at 15:27, C1.9 at 15:50, C2.0 at 18:01, C2.2 at 18:51, C1.3 at 19:35, C2.2 at 20:18 and C1.8 at 22:09 UTC.
Region 10657 was quiet and stable.
Spotted regions not numbered by NOAA/SEC:
[S443] This region rotated partly into view at the northeast limb late on August 8.
[S444] A new region emerged near the southeast limb on August 9.
August 7-9: No obviously Earth directed CMEs were detected in LASCO images.
August 8: A bright full halo CME was observed in LASCO C3 images starting at 09:42 UTC. The leading front was first observed off of the east limb and the south pole. The source of this event was likely about 5-6 days behind the southeast limb.
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 (CH108) in the southern hemisphere was in a geoeffective position on August 7. The southernmost part of a large, poorly defined coronal hole (CH109) in the northern hemisphere was in a geoeffective position on August 8-9.
Processed SOHO/EIT 284 image at 01:06 UTC on August 10. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to unsettled on August 9 with conditions becoming quiet to active on August 10-12 due to effects from coronal holes CH108 and CH109.
|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 very poor. Propagation along long distance north-south paths is fair. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay. Radio Vibración (Venezuela) was noted occasionally, as were a few unidentified Brazilian stations. On other frequencies propagation was best towards Brazil with several stations noted on 1540, 1560 and 1570 kHz. From North America WWZN on 1510 kHz was the only station heard and they had a weak 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|
classification was CAO,
area 0080 at midnight
classification was DKC,
area 0550 at midnight
|Total spot count:||71||56|
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||92.6 (1)||17.1 (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.