Solar Terrestrial Activity Report

Last major update issued on December 15, 2003 at 03:55 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update December 2, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update December 2, 2003)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update December 2, 2003)]
[Historical solar and geomagnetic data charts 1954-2003 (last update October 15, 2003)]
[Archived reports (last update December 8, 2003)]

Recent activity

The geomagnetic field was unsettled to minor storm on December 14. Solar wind speed ranged between 631 and 862 km/sec under the influence of a high speed stream from coronal hole CH71.

Solar flux measured at 20h UTC on 2.8 GHz was 92.4. The planetary A index was 24 (STAR Ap - based on the mean of three hour interval ap indices: 25.0).
Three hour interval K indices: 43344544 (planetary), 44343554 (Boulder).

The background x-ray flux is at the class B2 level.

At midnight there were 3 spotted regions on the visible disk. Solar flare activity was low.

Region 10520 decayed and lost several of the spots which had emerged one day earlier.
Region 10521 decayed slowly and quietly.
Region 10522 decayed early in the day, then new positive and negative polarity flux emerged at the center of the region. Spots of both polarities are present in the expanding central penumbra. The region will be rotating over the northwest limb on Dec.16. Flare: C1.1 at 19:40 UTC.

Coronal mass ejections (CMEs)

December 12-14: 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 huge recurrent trans equatorial coronal hole (CH71) was in a geoeffective position on December 5-11. Some decay was observed in the northern and western parts on December 9-10 and in the central southern and western parts on December 11-12. A recurrent coronal hole in the northern hemisphere (CH72) will likely rotate into a geoeffective position on December 17.

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


The geomagnetic field is expected to be quiet to active on December 15 as the current high speed stream weakens. Quiet to unsettled is likely on December 16-19 with unsettled to minor storm expected for December 20-21 as the high speed stream from coronal hole CH72 dominates the solar wind.

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 station tonight: Radio Cristal del Uruguay with a strong signal. Quite a few stations from Brazil were noted on several other frequencies].

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
10520 2003.12.10 10 7 N02E19 0140 DSO  
10521 2003.12.10 4 4 S12E21 0050 DSO  
10522 2003.12.13 4 8 N16W63 0030 CSO beta-gamma-delta
classification was DAO
at midnight, area 0050
S322 emerged on
    S15W02     plage
Total spot count: 18 19
SSN: 48 49

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)
2002.11 168.7 95.5 85.2 (-5.3)
2002.12 157.2 80.8 82.0 (-3.2)
2003.01 144.0 79.7 80.9 (-1.1)
2003.02 124.5 46.0 78.5 (-2.4)
2003.03 131.4 61.1 74.1 (-4.4)
2003.04 126.4 60.0 70.3 (-3.8)
2003.05 115.7 55.2 67.8 (-2.5)
2003.06 129.3 77.4 (65.3 predicted, -2.5)
2003.07 127.7 85.0 (61.9 predicted, -3.4)
2003.08 122.1 72.7 (59.0 predicted, -2.9)
2003.09 112.2 48.8 (57.0 predicted, -2.0)
2003.10 151.7 65.6 (54.3 predicted, -2.7)
2003.11 140.8 67.2 (51.6 predicted, -2.7)
2003.12 104.5 (1) 32.2 (2) (49.0 predicted, -2.6)

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]