Solar Terrestrial Activity Report

Last major update issued on October 2, 2005 at 04:35 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, 2005)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update October 2, 2005)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update October 2, 2005)]
[Historical solar and geomagnetic data charts 1954-2004 (last update February 1, 2005)]
[Archived reports (last update October 2, 2005)]

Recent activity

The geomagnetic field was quiet to active on October 1. Solar wind speed ranged between 453 and 550 (all day average 485) km/sec under the influence of a high speed stream from CH189.

Solar flux measured at 20h UTC on 2.8 GHz was 72.1. The planetary A index was 13 (STAR Ap - based on the mean of three hour interval ap indices: 13.0).
Three hour interval K indices: 34333233 (planetary), 24332123 (Boulder).

The background x-ray flux is at the class A2 level.

At midnight the visible solar disk was spotless. The solar flare activity level was very low. No C class events were recorded during the day. 

Coronal mass ejections (CMEs)

September 29 - October 1: No obvious fully or partly Earth directed CMEs were 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 small recurrent coronal hole (CH190) in the northern hemisphere could rotate to an Earth facing position on October 2.

Processed SOHO/EIT 284 image at 19:06 UTC on October 1. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to active on October 2 and mostly quiet October 3-9.

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. Propagation on long distance northeast-southwest paths is fair. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración (Venezuela). On other frequencies propagation varied quite a bit. At midnight UTC North American stations were heard on about 50 frequencies with some of those (i.e. 1450 and 1490 kHz) having more than 1 station. Later on most of these signals disappeared, however, the often heard station last season on 610 kHz, WIOD Miami FL, was heard for the first time this season. At 02h UTC and until 90 minutes before LSR stations from Colombia and Venezuela were strong on quite a few frequencies with Mara Ritmo 900 (Venezuela) and 970 Radio Super (Colombia) good examples of the current conditions. 820 Radio Paradise was very strong at 04h UTC.

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% lower.

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.