Last major update issued on August 21, 2004 at 05:35 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 unsettled to active on August 20. Solar wind speed ranged between 344 and 444 km/sec under the influence of a low speed coronal hole flow.
Solar flux measured at 20h UTC on 2.8 GHz was 121.4. The planetary A
index was 14 (STAR Ap - based on the mean of three hour interval ap indices: 14.6).
Three hour interval K indices: 33343333 (planetary), 33333433 (Boulder).
The background x-ray flux is at the class B3 level.
At midnight there were 5 spotted regions on the visible disk. The solar flare activity level was low. A total of 2 C class events was recorded during the day, a C2.8 flare at 01:07 and a C1.1 flare at 02:31 UTC, both from region 10656 behind the southwest limb.
Region 10661 was quiet and stable.
Region 10662 developed further and remained quiet.
Region 10663 was mostly unchanged and still has fairly large areas of bright plage.
New region 10664 emerged early on August 20 in the southeast quadrant.
Spotted regions not numbered by NOAA/SEC:
[S447] A new region emerged in the northeast quadrant on August 20. Location at midnight: N05E12
August 18: A CME was observed after the X1 flare in the afternoon. Most of the ejected material was observed over the
southwest limb, however, there were nearly simultaneous emissions over the east limb, and there is a slight chance that this was a
(faint) full halo CME.
August 19-20: 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 will likely rotate to a geoeffective position on August 21.
Processed SOHO/EIT 284 image at 01:06 UTC on August 21. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be mostly quiet to unsettled on August 21-23. A c weak coronal hole flow from coronal hole CH110 could reach Earth on August 24 and cause unsettled to active conditions.
|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. Propagation along long distance north-south paths is fair to good. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay and an unidentified station from Brazil. Around 03h UTC several station from North America could be heard, particularly above 1600 kHz, however, most of the stations were gone by local sunrise. After local sunrise propagation was best towards Argentina (710 Radio Diez, 790 Radio Mitre), Uruguay (770 Radio Oriental with a good signal) and Perú (1499.93 Radio Santa Rosa, 1590 Radio Agricultura "La Peruanissima")..
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 DKO
area was 0110
area was 0050
|Total spot count:||45||45|
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||115.4 (1)||50.8 (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.