Solar Terrestrial Activity Report

Last major update issued on July 11, 2006 at 01:40 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update June 7, 2006)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update June 7, 2006)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update June 7, 2006)]
[Historical solar and geomagnetic data charts 1954-2005 (last update March 3, 2006)]
[Archived reports (last update July 9, 2006)]

Recent activity

The geomagnetic field was quiet to unsettled on July 10. Solar wind speed ranged between 345 and 447 km/s (all day average 392 km/s - increasing 33 km/s over the previous day).

Solar flux measured at 20h UTC on 2.8 GHz was 72.8. The planetary A index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 11.4).
Three hour interval K indices: 31213333 (planetary), 32132322 (Boulder).

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

Region 10899 decayed further and could soon become spotless.

Coronal mass ejections (CMEs)

July 8-10: No partly or fully Earth directed CMEs were detected 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 coronal hole (CH231) in the southern hemisphere was in an Earth facing position on July 7-9.

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

Forecast

The geomagnetic field is expected to be quiet to active on July 11-12 due to a high speed stream from CH231 and mostly quiet July 13-16.

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) 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. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Radio Cristal del Uruguay was the best signal early in the night. Most of the other stations heard were from Argentina (best was 1190 Radio América, however, even 1610 Radio Guaviyú was audible at times) and Brazil.

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
10899 2006.07.05 8 2 S06W05 0030 CSO classification was HAX at midnight, area 0020
Total spot count: 8 2  
SSN: 18 12  

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)
2005.05 99.3 42.7 28.9 (-2.7)
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 (20.7 predicted, -2.3)
2006.02 76.5 4.7 (18.2 predicted, -2.5)
2006.03 75.4 10.8 (16.4 predicted, -1.8)
2006.04 89.0 30.2 (15.7 predicted, -0.7)
2006.05 80.9 22.2 (14.9 predicted, -0.8)
2006.06 76.5 13.9 (12.7 predicted, -2.2)
2006.07 82.1 (1) 10.6 (2) (11.3 predicted, -1.4)

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.


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