Solar Terrestrial Activity Report

Last major update issued on October 30, 2003 at 02:50 UTC.
No major updates will be issued October 31 - November 1 due to a DXLC board meeting.
Occasional minor updates may be posted.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update October 4, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update October 4, 2003)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update October 4, 2003)]
[Historical solar and geomagnetic data charts 1954-2003 (last update October 15, 2003)]
[Archived reports (last update October 30, 2003)]

Recent activity

The geomagnetic field was unsettled to extremely severe storm on October 29. Solar wind speed ranged between 572 and 1004 km/sec (SOHO solar wind data during the 07-18h UTC interval was invalid due to the radiation storm and the solar storm. Solar wind speed probably exceeded 1200 km/sec during the early part of the disturbance). A very strong solar wind shock was observed at ACE at about 06h UTC and reached the Earth about 20 minutes later. This shock was caused by the arrival of the CME observed after the X17 flare on October 28, the CME spent only 19 hours in transit (the fastest CME observed. A CME in 1859 is believed to have taken only 17 hours). Initially the interplanetary magnetic field was extremely strongly southwards and this caused geomagnetic storming reaching the maximum attainable level of 400 for the planetary A index during the 06-09h UTC interval. After the first couple of hours the IMF was northwards until 18h UTC. Then the IMF swung sharply southwards and stayed very strongly southwards for the remainder of the day. The geomagnetic storm is the strongest observed during solar cycle 23.

Solar flux measured at 20h UTC on 2.8 GHz was 291.7 (this is a new high for solar cycle 23. There have been days with higher solar flux at 20h UTC but those measurements have been flare enhanced). The planetary A index was 189 (STAR Ap - based on the mean of three hour interval ap indices: 191.9).
Three hour interval K indices: 43987798 (planetary), 43976798 (Boulder).

The background x-ray flux is at the class C3 level. The proton storm decreased in intensity after noon, then intensified following the X10 flare late in the day.

At midnight there were 11 spotted regions on the visible disk. Solar flare activity was high. A total of 5 C, 4 M and 1 X class events was recorded during the day.

Region 10484 decayed further and was quiet. The region is rotating over the west limb.
Region 10486 decayed slightly in the southeast and central parts. Flare potential is still very high and further X10+ proton flares are possible until the region rotates over the west limb on November 5. Flares: M3.5 long duration event peaking at 05:11, M1.2 at 06:09, M1.2 at 07:23, C9.2 at 14:22, C8.6 at 16:57 and X10.0/2B at 20:49 UTC. The X10 flare was associated with a strong type II and a moderate type IV radio sweep as well as a large earth directed CME..
Region 10487 developed and added a magnetic delta structure. Minor M class flares are possible.
Region 10488 developed further but not quite as quickly as during the previous days. Most of the development occurred in the trailing spot section where the dominant umbra became very large. Former region 10493 merged with region 10488 as 10488 expanded eastwards. The region could produce an X class flare. Flares: C9.3 long duration event peaking at 01:04, M1.1/1F at 01:51, C7.8 at 18:13 UTC.
Region 10489 developed early in the day, then decayed slowly.
Region 10490 decayed slowly and quietly and could soon become spotless.
Region 10491 developed slowly and quietly.
Region 10492 developed further. Early in the day a magnetic delta structure was evident in the trailing spot section, however, the region simplified somewhat later on.

Spotted regions not numbered by NOAA/SEC:
[S293] A new region emerged in the southeast quadrant on October 28 and developed quickly on October. How could this region escape being noticed by SEC? Location at midnight: S23E30.
[S294] A new region emerged in the southeast quadrant on October 29. Location at midnight: S09E41.
[S295] A new region emerged in the southeast quadrant due west of region S293 on October 29. Location at midnight: S24E21.

Coronal mass ejections (CMEs)

October 29: A very fast and large full halo CME was observed after the X10 flare in region 10486. The CME could reach Earth late on October 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

No obvious coronal holes are currently approaching geoeffective positions.

Processed SOHO/EIT 284 image at 15:29 UTC on October 29. Image quality is degraded because of the proton storm. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be at major to extremely severe storm levels on October 30-31 becoming active to major storm on November 1 (barring further major earth directed CMEs). Further major proton flares could occur anytime over the next week and cause extremely bad propagation on both low and high frequencies.

Long distance low frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is useless. Propagation along long distance north-south paths is very poor. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant stations none: nothing heard early on, after 02h UTC a very weak station from Brazil could be heard].

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.
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.

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.