Solar Terrestrial Activity Report

Last major update issued on December 6, 2003 at 05:15 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 1, 2003)]

Recent activity

The geomagnetic field was quiet to major storm on December 5. Solar wind speed ranged between 348 and 526 km/sec under the influence of a moderately high speed stream from coronal hole CH70. Effects from a halo CME observed on December 2 may have mixed with the coronal hole effects.

Solar flux measured at 20h UTC on 2.8 GHz was 111.7. The planetary A index was 43 (STAR Ap - based on the mean of three hour interval ap indices: 44.9).
Three hour interval K indices: 25655544 (planetary), 25545544 (Boulder).

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

At midnight there were 5 spotted regions on the visible disk. Solar flare activity was low. A total of 5 C class events were recorded during the day. A C1.1 event peaking near 19:10 UTC may have been associated with a filament eruption near region 10517. All other events occurred behind the southwest limb: C1.8 at 10:19, C1.1 at 13:47, C1.5 at 15:27 and C1.8 at 21:12 UTC. A filament eruption just south of region 10516 beginning a few minutes into December 6 may have been associated with a CME.

Region 10510 rotated quietly to the southwest limb.
Region 10513 was quiet and stable.
Region 10516 developed slowly as positive polarity flux emerged to the north of the leading negative polarity area.
Region 10517 was mostly unchanged and quiet.

Spotted regions not numbered by NOAA/SEC:
[S320] This region emerged with a single positive polarity spot on December 5 in the southwest quadrant. Location at midnight: S08W12.

Coronal mass ejections (CMEs)

December 3-5: 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 (CH70) was in a geoeffective position on December 1 - December 2. A huge recurrent trans equatorial coronal hole (CH71) will be in a geoeffective position on December 4-12 with the associated high speed stream influencing the geomagnetic field from December 7.

Processed SOHO/EIT 284 image at 01:05 UTC on December 6. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to major storm on December 5 due to effects from coronal hole CH70 and unsettled to minor on December 6. A strong high speed stream from coronal hole CH71 should dominate the solar wind from December 7 until approximately December 15 with mostly unsettled to minor storm conditions, isolated major and severe storm intervals are possible.

Long distance low frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is very poor to useless. Propagation along long distance north-south paths is fair. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay and Radio Rafaela (Argentina)].

Coronal holes (1)	Coronal mass ejections (2)	M and X class flares (3)

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.

Monthly solar cycle data

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.