Solar Terrestrial Activity Report

Last major update issued on November 19, 2003 at 04:40 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update November 4, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update November 4, 2003)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update November 4, 2003)]
[Historical solar and geomagnetic data charts 1954-2003 (last update October 15, 2003)]
[Archived reports (last update November 12, 2003)]

Recent activity

The geomagnetic field was quiet to active on November 18. Solar wind speed ranged between 610 and 761 km/sec under the influence of a high speed stream from coronal hole CH66. The high speed stream appeared to be ending late in the day.

Solar flux measured at 20h UTC on 2.8 GHz was 144.3. The planetary A index was 20 (STAR Ap - based on the mean of three hour interval ap indices: 20.3).
Three hour interval K indices: 44444432 (planetary), 54334433 (Boulder).

The background x-ray flux is at the class C1 level.

At midnight there were 4 spotted regions on the visible disk. Solar flare activity was moderate. A total of 8 C and 4 M class events were recorded during the day. Old region 10486 behind the southeast limb was the source of a long duration M4.5 event peaking at 10:11 and a C6.1 flare at 22:22 UTC.

Region 10501 gained some penumbral area and still has 3 magnetic delta structures. The main delta in the northern penumbra is not quite as strong as it was one day ago as the opposite polarity umbrae have increased their separation. A major flare is possible. Flares: M1.8 at 01:39, C2.3 at 02:12, C3.8 at 05:30, M3.2/2N long duration event peaking at 07:52 (associated with moderate type II and IV radio sweeps), M3.9 long duration event peaking at 08:31 and C3.7 at 22:49 UTC.
Region 10505 was mostly unchanged and quiet.
New region 10506 rotated into view at the southeast limb. This is not the return of region 10486, that region is still just behind the southeast limb.
New region 10507 rotated into view at the northeast limb. This is a large and complex region capable of producing major flares, including X class flares. There is a strong magnetic delta structure within the huge main penumbra. Flares: C4.1 at 01:02, C6.3 at 17:50 and C2.2 at 21:49 UTC.

Coronal mass ejections (CMEs)

November 18: A fairly faint full halo CME was observed after an M3.2 long duration event in region 10501 at 07:52 UTC. A faster and brighter halo CME was observed in LASCO images following an M3.9 long duration event in region 10501 at 08:31 UTC. These CMEs will combine into one and could reach Earth early on November 20.

A bright, fast and very large partial halo CME was observed after the long duration M4.5 event in old region 10486 just behind the southeast limb at 10:11 UTC.

November 17: A full, relatively faint, CME was observed after an M4 flare in region 10501 at 09:05 UTC. The CME could reach Earth sometime between 06 and 18h UTC on November 19.

November 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 coronal hole (CH68) in the northern hemisphere could rotate into a geoeffective position on November 20-21.

Processed SOHO/EIT 284 image at 19:05 UTC on November 18. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to active early on November 19. A CME could arrive during the day and cause unsettled to minor storm, perhaps briefly major storm conditions. Minor to severe geomagnetic storming is possible on November 20 when CMEs observed on November 18 will reach the Earth.

Long distance low frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is very poor. 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 at first, then Cadena Peruana de Noticias. Many station from Brazil noted on other frequencies, for instance 1480, 1510, 1540 and 1570 kHz].

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.