Solar Terrestrial Activity Report

Last major update issued on October 15, 2007 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 4, 2007)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update October 4, 2007)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update October 4, 2007)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports (last update October 3, 2007)]

Recent activity

The geomagnetic field was quiet on October 14. Solar wind speed ranged between 284 and 334 km/s (average speed was 301 km/s, decreasing 14 km/s from the previous day) under the influence of a low speed, high density stream from CH294.

Solar flux measured at 20h UTC on 2.8 GHz was 67.1. The planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 4.6). Three hour interval K indices: 11222101 (planetary), 11232111 (Boulder).

The background x-ray flux is below the class A1 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)

October 12-14: No obvious fully or partly Earth directed CMEs were observed in LASCO imagery.

Coronal holes

Coronal hole history (since late October 2002)
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago

A recurrent trans equatorial hole (CH295) will likely rotate into an Earth facing position on October 15-18. CH295 has become less well defined over the last solar rotation and has significantly decreased its areal coverage.

Processed STEREO-B 195 image at 20:45 UTC on October 14. The darkest areas on the solar disk are likely coronal holes.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is fair to good. Propagation on long distance northeast-southwest paths is poor.

Monitoring remarks from a location near N58E06: October 14: The morning was promising with stations like 1330 WLOL heard, however, propagation became gradually worse and stations from Florida (like 1080 WTPS and 1140 WQBA) had the best signals at 06:30 UTC. The best Trans Atlantic propagation sector was 270-310 degrees.

Forecast

The geomagnetic field is expected to be mostly quiet October 15-17. Quiet to occasionally active conditions are likely on October 18-21 due to a high speed stream from CH295. Quiet is expected for October 22-23 becoming quiet to minor storm on October 24 or 25.

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) Effects from a CME are likely to be observed at 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.

Active region Date numbered SEC
spot
count
STAR
spot
count
Location at midnight Area Classification Comment
               
Total spot count: 0 0  
SSN: 0 0  

Monthly solar cycle data

Month Average solar
flux at Earth
International sunspot number Smoothed sunspot number
2000.04 184.2 125.5 120.8
cycle 23 sunspot max.
2000.07 202.3 170.1 119.8
2001.12 235.1 132.2 114.6 (-0.9)
2006.08 79.0 12.9 15.6 (+0.3)
2006.09 77.8 14.4 15.6 (+0.0)
2006.10 74.3 10.4 14.2 (-1.4)
2006.11 86.3 21.5 12.7 (-1.5)
2006.12 84.5 13.6 12.1 (-0.6)
2007.01 83.3 16.9 12.0 (-0.1)
2007.02 77.7 10.6 11.6 (-0.4)
2007.03 72.2 4.8 10.8 (-0.8)
2007.04 72.4 3.7 (10.1 predicted, -0.7)
2007.05 74.4 11.7 (9.0 predicted, -1.1)
2007.06 73.7 12.0 (8.0 predicted, -1.0)
2007.07 71.6 10.0 (7.3 predicted, -0.7)
2007.08 69.1 6.2 (6.8 predicted, -0.5)
2007.09 67.1 2.4 (6.9 predicted, +0.1)
2007.10 67.9 (1) 1.3 (2) (7.6 predicted, +0.7)

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.


[DX-Listeners' Club]