Solar Terrestrial Activity Report

Last major update issued on January 20, 2005 at 04:45 UTC. Last minor update posted at 13:02 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 19, 2005)]

Recent activity

The geomagnetic field was unsettled to severe storm on January 19. Solar wind speed ranged between 722 and 1002 km/sec. gradually decreasing all day. A solar wind abnormality was observed at 03:10 UTC on January 20 when wind speed increased suddenly from near 650 to near 800 km/sec at ACE Solar wind temperature increased considerably as well, however, the total field of the IMF became weak and there was no significant change in wind density.

Solar flux measured at 20h UTC on 2.8 GHz was 132.5. The planetary A index was 62 (STAR Ap - based on the mean of three hour interval ap indices: 62.0).
Three hour interval K indices: 66676434 (planetary), 56565533 (Boulder).

The background x-ray flux is at the class B5 level.

At midnight there were 4 spotted regions on the visible solar disk. The solar flare activity level was high. A total of 8 C, 3 M and 1 X class events was recorded during the day.

Region 10718 decayed slowly and quietly and is rotating over the southwest limb.
Region 10720 changed considerably with the positive polarity field in the the southern part of the main penumbra weakening. Positive polarity flux emerged in the north and the northernmost penumbra increased in area and complexity. Another major flare is possible. Flares: C3.1 at 00:20, C3.8 at 00:50, C1.8 at 03:24, C1.9 at 04:48, C7.2 at 05:26, long duration major M6.7/2N peaking at 07:31, major X1.3 at 08:22 (associated with moderate type II and IV radio sweeps and a halo CME), M2.7/1N at 10:23, C6.6 at 12:51, M1.6 at 15:40 UTC.
Region 10723 was quiet and stable.

Spotted regions not numbered by NOAA/SEC:
S501: This region emerged in the southeast quadrant on January 19. Location at midnight: S02E54. Flare: C5.3 at 23:24 UTC

Comment added at 07:04 UTC on January 20: Region 10720 has just produced a giant X7.1 proton flare. A very strong proton storm has already started at Earth, this is likely to seriously degrade radio communications over the next days, particularly for polar and near polar signal paths. Further updates will be posted later on ... This could become the largest proton storm during this solar cycle. The above 100 MeV proton flux is already past the 400 pfu mark.

Comment added at 13:02 UTC: Type II and IV radio sweeps were recorded along with the X7 flare. It is likely that the flare was associated with a large CME, however, LASCO images covering this event are unavailable at this time. Those images might not be very interesting either because of strong proton contamination. The CME is likely to have had some Earth directed component and could reach our planet on January 21 or 22. The current proton storm peaked soon after the flare reached its peak with the above 100 MeV flux reaching about 700 pfu, while the above 10 MeV flux had a maximum near 2000 pfu. The proton storm has not become as intense as the first numbers suggested.

Coronal mass ejections (CMEs)

January 19: A full halo CME was observed after the X1 event in region 10720 during the morning. This CME could reach Earth on January 21 as expansion speed in the direction of Earth was much slower than towards the northwest.
January 18
: No obvious fully or partly Earth directed CMEs were observed.
January 17
: A large and fast full halo CME was observed after the X3 event in region 10720 during the UTC morning.

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

A fairly large delta shaped recurrent coronal hole (CH140) in the northern hemisphere was in a geoeffective position on January 18-20. The associated high speed stream will likely become geoeffective on  January 21.

Processed SOHO/EIT 284 image at 14:13 UTC on January 19. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to minor storm on January 20 and quiet to major storm on January 21 due to CME effects. The high speed stream from coronal hole CH140 could arrive late on January 21 and will probably cause unsettled to minor storm conditions on January 22-23.

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 very poor. Propagation along long distance north-south paths is poor to fair. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay. AM de Parelhas (Brazil) was noted too and there were even other stations from Brazil at times. Radio Vibración (Venezuela) was heard occasionally. On other frequencies propagation was best towards Brazil with Rádio 9 de Julho on 1600 kHz providing the best and most stable signal. From North America WWZN on 1510 had a fair signal at times, stations were observed on 1660, 1680 and 1700 kHz as well.

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 3 3 S06W76 0110 DAO classification was DSO at midnight
10720 2005.01.10 31 37 N14W56 1220  EKC beta-gamma-delta
10721 2005.01.16     S03W24     plage
10722 2005.01.16     N19W38     plage
10723 2005.01.17 2 1 N06E52 0070 CAO classification was HSX at midnight
10724 2005.01.18     S12W20      
S494 emerged on

S495 visible on

S500 visible on
    N10E57     plage
S501 emerged on
  1 S02E54 0010 HRX  
Total spot count: 36 42  
SSN: 66 92  

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)
2005.01 106.7 (1) 33.4 (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]