Solar Terrestrial Activity Report

Last major update issued on October 12, 2004 at 02:40 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 11. Solar wind speed ranged between 381 and 434 km/sec under the influence of a fairly low speed stream from coronal hole CH118.

Solar flux measured at 20h UTC on 2.8 GHz was 87.9. The planetary A index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 11.8).
Three hour interval K indices: 33213323 (planetary), 24213223 (Boulder).

The background x-ray flux is at the class A6 level.

At midnight there was 1 spotted region on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day.

Spotted regions not numbered by NOAA/SEC:
[S458] This region emerged on October 11 in the northeast quadrant. Only positive polarity spots have been observed so far, and the region appeared to be slowly decaying late in the day.

Coronal mass ejections (CMEs)

October 9-11: No obviously Earth directed CMEs observed in limited LASCO data.

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 11. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on October 12-13 due to a fairly low speed stream from coronal hole CH118. Quiet conditions are likely 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 poor. Propagation along long distance north-south paths is poor. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant stations tonight: none, several weak signals were detected, one of them was Radio Vibración (Venezuela). On other frequencies propagation was best towards Newfoundland and Puerto Rico. The often heard Newfoundland stations on 560, 590, 620, 650, 710, 750, 800 and 930 kHz all had fair signals. The only audible USA stations were WBZ 1030, WBBR 1130 and WWZN 1510.

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.