Last major update issued on October 13, 2004 at 02:50 UTC.
[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update October 2, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update October 2, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update October 2, 2004)]
[Historical solar and geomagnetic data charts 1954-2004 (last update August 28, 2004)]
[Archived reports (last update October 10, 2004)]
The geomagnetic field was quiet to unsettled on October 12. Solar wind speed ranged between 385 and 447 km/sec under the influence of a fairly low speed stream from coronal hole CH118. A new disturbance arrived near midnight.
Solar flux measured at 20h UTC on 2.8 GHz was 87.6. The planetary A
index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 12.0).
Three hour interval K indices: 33332223 (planetary), 33332213 (Boulder).
The background x-ray flux is at the class A5 level.
At midnight there were 2 spotted regions on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day.
New region 10681 emerged in the northeast quadrant on October 11 and was numbered by SEC the next day. The region became more complex as a negative polarity area emerged in the midst of positive polarity. There is potential for further development and C class flares. With the current alignment of the opposite polarities, a magnetic delta structure could easily form.
Spotted regions not numbered by NOAA/SEC:
[S459] This region rotated into view at the southeast limb on October 12.
October 10-12: No obviously Earth directed CMEs observed in limited LASCO data.
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 recurrent coronal hole (CH118) in the southern hemisphere was in a geoeffective position on October 8-9.
Processed SOHO/EIT 284 image at 19:06 UTC on October 12. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to active on October 13 and mostly quiet on October 14-16.
|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 poor to very poor. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay. On other frequencies only a few stations were heard, mostly from Newfoundland (fair to good signals on 590, 620, 750, 800 and 930 kHz).
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 DAO
at midnight, area 0040
|Total spot count:||4||10|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2004.04||101.2||39.3||(44.6 predicted, -2.5)|
|2004.05||99.8||41.5||(40.9 predicted, -3.7)|
|2004.06||97.4||43.2||(38.0 predicted, -2.9)|
|2004.07||119.1||51.0||(36.2 predicted, -1.8)|
|2004.08||109.6||40.9||(34.6 predicted, -1.6)|
|2004.09||103.1||27.7||(32.8 predicted, -1.6)|
|2004.10||89.6 (1)||10.8 (2)||(30.5 predicted, -2.3)|
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.