Solar Terrestrial Activity Report

Last major update issued on January 25, 2005 at 05:00 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 quiet on January 24. Solar wind speed ranged between 547 and 650 km/sec under the weakening influence of a high speed stream from coronal hole CH140.

Solar flux measured at 20h UTC on 2.8 GHz was 94.6. The planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 6.5).
Three hour interval K indices: 21122221 (planetary), 21222221 (Boulder).

The background x-ray flux is at the class A8 level.

At midnight there were 4 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 10723 was quiet and stable.
Region 10725 decayed slowly and rotated to the southwest limb.
New region 10727 emerged in the southeast quadrant. The rate of  development was initially very quick, however, the opposite polarity fields did display better separation towards the end of the day. Coronal hole CH142 lost some of its most southerly extensions due to the development of this region.

Spotted regions not numbered by SEC/NOAA:
[S504] This region emerged in the southeast quadrant on January 24. Location at midnight: S12E03.

Coronal mass ejections (CMEs)

January 22-24: 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

A coronal hole (CH141) in the southern hemisphere could rotate to a geoeffective position on January 25-26. A recurrent trans equatorial coronal hole (CH142) will likely rotate to a geoeffective position on January 27-29.

Processed SOHO/EIT 284 image at 01:06 UTC on January 25. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be mostly quiet on January 25-27. On January 28-29 a high speed stream from coronal hole CH141 is likely to cause unsettled to active conditions while effects from coronal hole CH142 could extend these conditions until February 1.

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.

Propagation

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 very poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración (Venezuela) with a very weak signal. A few stations from North America were heard with mostly weak signals, CJYQ on 930 kHz had the best signal.

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
spot
count
STAR
spot
count
Location at midnight Area Classification Comment
10721 2005.01.16     S03W89     plage
10723 2005.01.17 1 1 N06W17 0070 HSX location: N05W18
10724 2005.01.18     S12W85     plage
10725 2005.01.21 3 1 S03W77 0110 CSO classification was HSX at midnight, area 0070
location: S04W79
10726 2005.01.21     S01W15     plage
10727 2005.01.24 8 7 S09E38 0320 DAI classification was DAO at midnight, area 0080
location: S08E36
S495 visible on
2005.01.13
 
S06W48

plage
S500 visible on
2005.01.18
    N10W08     plage
S503 emerged on
2005.01.23
    S22W71     plage
S504 emerged on
2005.01.24
  1 S12E03 0010 HRX  
Total spot count: 12 10  
SSN: 42 50  

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)
2005.01 106.5 (1) 42.2 (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]