Solar Terrestrial Activity Report

Last major update issued on January 15, 2005 at 05:20 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update January 2, 2005)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update January 2, 2005)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update January 2, 2005)]
[Historical solar and geomagnetic data charts 1954-2004 (last update November 8, 2004)]
[Archived reports (last update January 12, 2005)]

Recent activity

The geomagnetic field was quiet to active on January 14. Solar wind speed ranged between 532 and 757 km/sec under the influence of a high speed stream from coronal hole CH139.

Solar flux measured at 20h UTC on 2.8 GHz was 129.8. The planetary A index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 11.6).
Three hour interval K indices: 22211144 (planetary), 23212244 (Boulder).

The background x-ray flux is at the class C2 level.

At midnight there were 4 spotted regions on the visible solar disk. The solar flare activity level was high. A total of 28 C and 5 M class events was recorded during the day. This is the highest number of C flares in a single day during solar cycle 23.

Region 10718 developed further in the trailing spot section which still has a magnetic delta structure.  to form. A minor M class flare is possible. Flares: C9.3 at 04:04, C8.9 at 10:22, C4.6 at 12:41 (associated with a weak type II radio sweep) and M1.0 at 16:06 UTC.
Region 10720 developed with the single penumbra expanding into the largest penumbra observed during solar cycle 23. Within this penumbra there are two major areas with negative polarity, one in the northeast and northern central part and another in the northwest. Both of these areas have long neutral inversion lines to the extremely strong positive polarity field in the south. That positive polarity area has the longest and largest umbra I have ever observed. At its western end this umbra is actually in contact (no space between) with the negative polarity umbra in the northwestern part of the penumbra. This is causing exceptional magnetic shear and extremely energetic flares, above the X10 class level, are possible. This region has the potential to generate flares similar to those observed in October/November 2003. Flares: C1.0 at 00:14, C1.4 at 02:43, C1.0 at 05:49, C6.8 at 07:38, C1.4 at 08:37, C1.8 at 08:58, C1.9 at 09:17, C1.0 at 09:55, C8.5 at 10:15 (SEC had this event mixed with the nearly simultaneous C8.9 event in region 10718), C2.3 at 11:44, C2.1 at 12:05, C2.4 at 13:42, M1.8 at 14:11, M1.5 at 14:22, C8.0 at 15:51, C2.5 at 16:58, C2.8 at 17:42, M1.5 at 17:57, C6.8 at 18:29, C7.7 at 18:41, C3.3 at 19:11, C1.4 at 19:36, C1.2 at 20:30, C2.5 at 21:05, M1.9 at at 21:26, C9.6 at 22:03, C3.0 at 22:26,  C6.0 at 22:55 and C5.6 at 23:33 UTC. Early on January 15 the following flares have been recorded: C9.8 at 00:27, major X1.2 at 00:43, C2.9 at 02:39, C2.2 at 03:21, C4.2 at 03:40, M1.3 at 04:16 and major impulsive M8.4 at 04:33 UTC.

Spotted regions not numbered by NOAA/SEC:
S494: This region emerged on January 13 just north of the leading penumbra in region 10718 and developed slowly on January 14.
S495: A small region rotated into view late on January 13 at the southeast limb. At one point during the day this region was spotless, however, a single small spot was observed again late in the day.

Coronal mass ejections (CMEs)

January 12-14: No obvious fully or partly Earth directed CMEs were observed.

Coronal holes

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

An extension (CH139) of a large coronal hole in the northern hemisphere was in a geoeffective position on January 9-11.

Processed SOHO/EIT 284 image at 01:06 UTC on January 15. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to active on January 15-16. Depending on activity in regions 10718 and 10720 CMEs could begin arriving on January 17.

Coronal holes (1) Coronal mass ejections (2) M and X class flares (3)
Coronal hole indicator CME indicator M and X class flare indicator

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 Cristal del Uruguay with a weak signal. Only a few trans Atlantic stations were noted on other frequencies: 590 VOCM, 740 Rádio Sociedade, 930 CJYQ / Rádio Metropolitana / CBN, 1510 WWZN.

Active solar regions (Recent map)

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
10718 2005.01.07 22 31 S05W06 0250 FAO beta-gamma-delta
area was 0300
at midnight
location: S07W10
10720 2005.01.10 23 28 N13E10 1540 DKC delta
area was 1950
at midnight
location: N13E08
S493 emerged on
    S16W58     plage
S494 emerged on
  3 S01W17 0030 CAO
S495 visible on
  1 S06W67 0000 AXX
Total spot count: 45 63
SSN: 65 103

Monthly solar cycle data

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)
2003.11 140.8 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 41.7 (-2.2)
2004.07 119.1 51.0 (39.6 predicted, -1.9)
2004.08 109.6 40.9 (38.0 predicted, -1.6)
2004.09 103.1 27.7 (36.1 predicted, -1.9)
2004.10 105.9 48.4 (33.9 predicted, -2.2)
2004.11 113.2 43.7 (32.0 predicted, -1.9)
2004.12 94.5 17.9 (29.7 predicted, -2.3)
2005.01 96.0 (1) 17.9 (2) (27.0 predicted, -2.7)

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.

[DX-Listeners' Club]