Last major update issued on December 22, 2004 at 03:50 UTC.
[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update December 3, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update December 3, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update December
3, 2004)]
[Historical solar and geomagnetic data charts 1954-2004 (last update November 8,
2004)]
[Archived reports (last update December 14, 2004)]
The geomagnetic field was quiet to minor storm on December 21. Solar wind speed ranged between 350 and 473 km/sec. A high speed stream from coronal hole CH134 arrived after 05h UTC.
Solar flux measured at 20h UTC on 2.8 GHz was 101.0. The planetary A
index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 12.3).
Three hour interval K indices: 21352322 (planetary), 21342312 (Boulder).
The background x-ray flux is at the class B2 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.
Region 10713 developed slowly and could produce C class flares.Spotted regions not numbered by NOAA/SEC:
[S490] A new region emerged in the southeast quadrant just northwest of region 10713 on December 21.
December 19-20: No obviously Earth directed CMEs observed.
December 21: Very few images available.
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 (CH134) in the southern hemisphere was in a geoeffective position on December 18. A recurrent coronal hole (CH135) in the northern hemisphere will be in a geoeffective position on December 23-24.
Processed SOHO/EIT 284 image at 18:03 UTC on December 11. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to minor storm on December 22 and quiet to unsettled on December 23 due to effects from coronal hole CH134. Mostly quiet conditions are likely on December 24-25. Another coronal hole flow could arrive on December 26 and cause unsettled to minor storm conditions that day and on December 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. Propagation along long distance north-south paths is poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración (Venezuela). On other frequencies propagation was best towards the Caribbean and Newfoundland. Some of the 50 kW stations in New York and Boston were audible as well. Both WDHP on 1620 and Radio Juventus Don Bosco on 1640 kHz had fair signals.
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 spot count |
STAR spot count |
Location at midnight | Area | Classification | Comment |
|---|---|---|---|---|---|---|---|
| 10712 | 2004.12.17 | S11W02 | plage | ||||
| 10713 | 2004.12.17 | 15 | 13 | S08E22 | 0210 | EAI |
beta-gamma classification was EKO at midnight, area 0280 |
| S490 | emerged on 2004.12.21 |
3 | S03E10 | 0020 | DSO | ||
| Total spot count: | 15 | 16 | |||||
| SSN: | 25 | 36 | |||||
| Month | Average solar flux at Earth |
International sunspot number | Smoothed sunspot number |
|---|---|---|---|
| 2000.04 | 184.2 | 125.5 | 120.8 cycle 23 sunspot max. |
| 2000.07 | 202.3 | 170.1 | 119.8 |
| 2001.12 | 235.1 | 132.2 | 114.6 (-0.9) |
| 2003.10 | 151.7 | 65.5 | 58.2 (-1.3) |
| 2003.11 | 140.8 | 67.3 | 56.7 (-1.5) |
| 2003.12 | 114.9 | 46.5 | 54.8 (-1.9) |
| 2004.01 | 114.1 | 37.3 | 52.0 (-2.8) |
| 2004.02 | 107.0 | 45.8 | 49.3 (-2.7) |
| 2004.03 | 112.0 | 49.1 | 47.1 (-2.2) |
| 2004.04 | 101.2 | 39.3 | 45.5 (-1.6) |
| 2004.05 | 99.8 | 41.5 | 43.9 (-1.6) |
| 2004.06 | 97.4 | 43.2 | (42.2 predicted, -1.7) |
| 2004.07 | 119.1 | 51.0 | (40.6 predicted, -1.6) |
| 2004.08 | 109.6 | 40.9 | (39.0 predicted, -1.6) |
| 2004.09 | 103.1 | 27.7 | (37.1 predicted, -1.9) |
| 2004.10 | 105.9 | 48.4 | (34.9 predicted, -2.2) |
| 2004.11 | 113.2 | 43.7 | (33.0 predicted, -1.9) |
| 2004.12 | 93.1 (1) | 24.1 (2) | (30.7 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.
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