Solar Terrestrial Activity Report

Last major update issued on August 8, 2006 at 04:45 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update August 6, 2006)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update August 6, 2006)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update August 6, 2006)]
[Historical solar and geomagnetic data charts 1954-2005 (last update March 3, 2006)]
[Archived reports (last update August 6, 2006)]

Recent activity

The geomagnetic field was quiet to major storm on August 7. Solar wind speed ranged between 334 and 647 km/s (all day average 527 km/s - increasing 187 km/s over the previous day) under the influence of a high speed stream from CH235.

Solar flux measured at 20h UTC on 2.8 GHz was 69.8. The planetary A index was 32 (STAR Ap - based on the mean of three hour interval ap indices: 31.8).
Three hour interval K indices: 33665332 (planetary), 34664333 (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:
[S670] This region is emerging near the southeast limb. C flares are possible. Location at midnight: S08E68

Coronal mass ejections (CMEs)

August 5-7: No partly or fully Earth directed CMEs were detected in LASCO imagery. A faint full halo CME was observed in a LASCO C3 movie starting before noon on August 7. With no frontside activity its source is likely to have been just to the northwest of the backside disk center.

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 coronal hole (CH235) in the southern hemisphere (with a trans equatorial extension) was in an Earth facing position on August 2-4.

Processed SOHO/EIT 284 image at 19:06 UTC on August 7. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on August 8-10 and quiet on August 11-13.

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.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is very poor. Propagation on long distance northeast-southwest paths is fair. The only stations from North America with audio was 930 CJYQ. Propagation was best to Argentina, Chile (1140, 1180 and 1380 kHz) Uruguay and Paraguay (780, 920, 1020, 1480 kHz) with the best signals noted from stations in the Buenos Aires area.

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
S670 2006.08.07   1 S08E68 0010 AXX  
Total spot count: 0 1  
SSN: 0 11  

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)
2005.06 93.7 39.3 28.8 (-0.1)
2005.07 96.4 40.1 29.1 (+0.3)
2005.08 90.5 36.4 27.4 (-1.7)
2005.09 91.1 21.9 25.8 (-1.6)
2005.10 77.0 8.5 25.5 (-0.3)
2005.11 86.3 18.0 24.9 (-0.6)
2005.12 90.7 41.2 23.0 (-1.9)
2006.01 83.4 15.4 20.8 (-2.2)
2006.02 76.5 4.7 (18.4 predicted, -2.4)
2006.03 75.4 10.8 (16.6 predicted, -1.8)
2006.04 89.0 30.2 (15.9 predicted, -0.7)
2006.05 80.9 22.2 (15.1 predicted, -0.8)
2006.06 76.5 13.9 (12.9 predicted, -2.2)
2006.07 75.7 12.2 (11.4 predicted, -1.5)
2006.08 70.7 (1) 1.8 (2) (11.4 predicted, -0.0)

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]