Solar Terrestrial Activity Report

Last major update issued on December 31, 2003 at 05:05 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 30, 2003)]

Recent activity

The geomagnetic field was quiet to unsettled on December 30. Solar wind speed ranged between 359 and 451 km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 107.7. The planetary A index was 8 (STAR Ap - based on the mean of three hour interval ap indices: 9.5).
Three hour interval K indices: 21322332 (planetary), 11312233 (Boulder).

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

At midnight there was 1 spotted region on the visible disk. Solar flare activity was low with a single C class flare recorded.

Region 10528 decayed further and rotated partly out of view at the northwest limb. Flare: C1.0 at 19:40 UTC.

Coronal mass ejections (CMEs)

December 28-29: No partly or fully earth directed CMEs observed. Only a few new LASCO images were published on December 28 and 29 and none on December 30.

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 (CH73) was in a geoeffective position on December 28-29. A recurrent trans equatorial coronal hole (CH74) is rotating into view at the east limb and will be in a geoeffective position from January 1.

Processed SOHO/EIT 284 image at 19:06 UTC on December 26. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to unsettled early on December 31, then become unsettled to minor storm as a high speed stream from coronal hole CH73 dominates the solar wind. Quiet to unsettled is likely again on January 2-3.

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 fair to good. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay with a very good signal on the southwesterly antenna. On the same antenna Rádio Papacaça (Bom Conselho, Brazil) and Radio Rafaela (Argentina) were noted during brief Radio Cristal fades. On the westerly antenna WLAM Lewiston could be heard early in the night].

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
10528 2003.12.18 5 2 N10W81 0100 FAO classification was HAX
at midnight, leading
spots rotated out of
10530 2003.12.21     S22W54     plage
10532 2003.12.25     S12W64     plage
10533 2003.12.28     N16E25     plage
Total spot count: 5 5
SSN: 15 12

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 80.8 (-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 (65.1 predicted, -2.5)
2003.07 127.7 83.3 (61.8 predicted, -3.3)
2003.08 122.1 72.7 (58.8 predicted, -3.0)
2003.09 112.2 48.7 (56.9 predicted, -1.9)
2003.10 151.7 65.6 (54.1 predicted, -2.8)
2003.11 140.8 67.2 (51.4 predicted, -2.7)
2003.12 115.3 (1) 75.3 (2) (48.9 predicted, -2.5)

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]