Solar Terrestrial Activity Report

Last major update issued on October 11, 2004 at 03:25 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update October 2, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update October 2, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update October 2, 2004)]
[Historical solar and geomagnetic data charts 1954-2004 (last update August 28, 2004)]
[Archived reports (last update October 10, 2004)]

Recent activity

The geomagnetic field was quiet to unsettled on October 10. Solar wind speed ranged between 319 and 408 km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 89.0. The planetary A index was 8 (STAR Ap - based on the mean of three hour interval ap indices: 8.8).
Three hour interval K indices: 33032222 (planetary), 33122221 (Boulder).

The background x-ray flux is at the class B1 level.

At midnight the visible solar disk was spotless. The solar flare activity level was low. A total of 1 C class event was recorded during the day. This flare was  from region 10680 behind the northwest limb, a C2.0 event at 03:28 UTC.

Coronal mass ejections (CMEs)

October 8-10: No obviously 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 coronal hole (CH118) in the southern hemisphere was in a geoeffective position on October 8-9.

Processed SOHO/EIT 284 image at 19:06 UTC on October 10. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to active on October 11-12 due to a high speed stream from coronal hole CH118. Quiet to unsettled is likely on October 13 becoming quiet on October 14-16.

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.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is fair to good. Propagation along long distance north-south paths is poor. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant stations tonight: WLAM Lewiston ME from 23 to 00:30 UTC, then WWNN Pompano Beach FL and WWBG Greensboro NC. On other frequencies propagation was best towards the northeastern USA and the Canadian Atlantic provinces around midnight UTC, while stations from the southeastern USA enjoyed better reception than usual after 00:30 UTC. The Miami stations on 610 (WIOD) and 1140 (WQBA) kHz both had fair to good signals.

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 some of these solar data sources. All time references are to the UTC day. Comments and suggestions are always welcome.