Solar Terrestrial Activity Report

Last major update issued on July 9, 2006 at 05:00 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 inactive to quiet on July 8. Solar wind speed ranged between 350 and 532 km/s (all day average 413 km/s - decreasing 105 km/s from the previous day).

Solar flux measured at 20h UTC on 2.8 GHz was 77.4. The planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.4).
Three hour interval K indices: 10201112 (planetary), 10201100 (Boulder).

The background x-ray flux is at the class A3 level.

At midnight there were 2 spotted regions on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day.

Region 10898 decayed slowly and was mostly quiet. The main penumbra appears to be fragmenting both in the northern and southern parts.
Region 10899 decayed slowly and quietly.

Coronal mass ejections (CMEs)

July 7-8: No partly or fully Earth directed CMEs were detected in LASCO imagery.
July 6: A large full halo CME was observed after the M2 event in region 10898. While the core of this CME is not likely to reach Earth, some of the ejected material is heading our way and could reach Earth sometine on July 9.

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 01:06 UTC on July 9. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to become unsettled to minor storm on July 9 when the CME mentioned above reaches Earth. A high speed stream from CH231 will probable dominate the solar wind on July 10-12 and cause quiet to minor storm conditions.

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.


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 good to very good. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Radio Cristal del Uruguay had the best signal tonight, however, two stations from Argentina were noted at times. Many stations were heard on other frequencies, quite a few with good signals. 1350 kHz had several stations with Rádio Cristal and Radio Buenos Aires at times excellent. 850 Carve, 930 Montecarlo and 1410 AM Libre (all Uruguay) were other stations with unusually good signals. Usable audio was heard until about 2 hours after LSR on several frequencies - 1520 kHz had presumed Radio Chascomus (Argentina) at 04:30 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.

Active region Date numbered SEC
Location at midnight Area Classification Comment
10898 2006.06.28 9 7 S06W69 0360 DKC classification was DKO at midnight, area 0290
10899 2006.07.05 5 4 S05E27 0060 DAO classification was DSO at midnight
Total spot count: 14 11  
SSN: 34 31  

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 84.2 (1) 9.0 (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.

[DX-Listeners' Club]