Solar Terrestrial Activity Report

Last major update issued on January 17, 2004 at 04:10 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update January 4, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update January 4, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update January 4, 2004)]
[Historical solar and geomagnetic data charts 1954-2003 (last update January 16, 2004)]
[Archived reports (last update January 9, 2004)]

Recent activity

The geomagnetic field was unsettled to minor storm on January 16. Solar wind speed ranged between 548 and 728 km/sec. The high speed stream from coronal hole CH76 arrived during the evening of January 15. Solar wind speed increased slowly all day on January 16.

Solar flux measured at 20h UTC on 2.8 GHz was 120.3. The planetary A index was 26 (STAR Ap - based on the mean of three hour interval ap indices: 27.0).
Three hour interval K indices: 44354454 (planetary), 42243444 (Boulder).

The background x-ray flux is at the class B3 level.

At midnight there were 4 spotted regions on the visible disk. Solar flare activity was very low. No C class events was recorded during the day.

Region 10537 decayed further and lost about half of its penumbral area during the day. A few new leader spots emerged.
Region 10540 decayed in the trailing spot section and was quiet. C flares are possible.
Region 10541 developed quickly and had a magnetic delta structure at noon. Late in the day the single penumbra split into two separate penumbrae and the region became more stable.
New region 10542 rotated into view at the northeast limb on January 14 and was noticed by NOAA/SEC two days later. This region decayed slowly during the day.

There is an unusually large and dense J-shaped filament in the northeast quadrant and rotating into the northwest quadrant, it is trailing coronal hole CH76 and has nearly the same shape. An eruption of this filament will cause a large CME.

Coronal mass ejections (CMEs)

January 14-16: No partly or fully earth directed CMEs 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 recurrent trans equatorial coronal hole (CH76) was in a geoeffective position on January 13-17.

Processed SOHO/EIT 284 image at 19:06 UTC on January 16. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be unsettled to active on January 17-20 due to a high speed stream from coronal hole CH76. Quiet to unsettled is likely on January 21-22.

Long distance low 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 good. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant stations tonight: Radio Rafaela (Argentina) and Rádio Morro Verde (Brazil). There were lots of station from northeast Brazil on other frequencies as well on the southwesterly longwire. Switching in the northwesterly EWE brought several stations from Newfoundland, Nova Scotia and a few US east coast stations].

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.

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
10537 2004.01.06 10 11 N04W57 0160 DAC classification was CAO
at midnight, area 0090
10539 2004.01.07     N09W89     plage
10540 2004.01.12 13 18 S13E28 0350 EAO classification was ESO
at midnight
10541 2004.01.15 3 6 S09W18 0010 BXO classification was DAO
at midnight, area 0060
10542 2004.01.16 2 3 N11E54 0060 CSO classification was HAX
at midnight, area 0030
Total spot count: 28 38
SSN: 68 78

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)
2002.12 157.2 80.8 82.0 (-3.2)
2003.01 144.0 79.7 80.8 (-1.2)
2003.02 124.5 46.0 78.3 (-2.5)
2003.03 131.4 61.1 74.0 (-4.3)
2003.04 126.4 60.0 70.1 (-3.9)
2003.05 115.7 55.2 67.6 (-2.5)
2003.06 129.3 77.4 65.0 (-2.6)
2003.07 127.7 83.3 (62.0 predicted, -3.0)
2003.08 122.1 72.7 (59.4 predicted, -2.6)
2003.09 112.2 48.7 (57.5 predicted, -1.9)
2003.10 151.7 65.6 (54.7 predicted, -2.8)
2003.11 140.8 67.2 (52.0 predicted, -2.7)
2003.12 114.9 47.0 (49.4 predicted, -2.6)
2004.01 118.8 (1) 35.5 (2) (45.3 predicted, -4.1)

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 sources noted in solar links. All time references are to the UTC day. Comments and suggestions are always welcome.

[DX-Listeners' Club]