Solar Terrestrial Activity Report

Last major update issued on July 6, 2006 at 04:25 UTC. Minor updated posted at 13:50 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 June 5, 2006)]

Recent activity

The geomagnetic field was quiet to minor storm on July 5. Solar wind speed ranged between 563 and 739 km/s (all day average 608 km/s - increasing 212 km/s over the previous day) under the influence of a high speed stream from CH230.

Solar flux measured at 20h UTC on 2.8 GHz was 84.7. The planetary A index was 19 (STAR Ap - based on the mean of three hour interval ap indices: 19.4).
Three hour interval K indices: 45522224 (planetary), 44522323 (Boulder).

The background x-ray flux is at the class A8 level.

At midnight there were 2 spotted regions on the visible solar disk. The solar flare activity level was low. A total of 1 C class event was recorded during the day.

Region 10898 did not change much. The only development of interest was that the large umbra split into two smaller umbrae. Flare: C1.2 at 08:58 UTC.
New region 10899 rotated into view at the southeast limb on July 4 and was numbered the next day by NOAA/SEC. A C flare is possible.

Two duopoles with the expected polarity of cycle 24 were observed on July 5, one located at midnight at S26W22 while the other one was at S45E24.

Comment posted at 13:50 UTC on July 6: Region 10898 produced an M2.5/2F flare at 08:36 UTC. This event was associated with type II and IV radio sweeps and a minor proton enhancement. A large CME was observed over the southwest limb. LASCO C2 difference movies indicate a full halo CME. Parts of this CME could reach Earth on July 8 or 9 and cause unsettled to major storm conditions.

Coronal mass ejections (CMEs)

July 3-5: 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 trans equatorial coronal hole (CH230) was in an Earth facing position on July 1-3. A recurrent coronal hole (CH231) in the southern hemisphere will likely rotate into an Earth facing location on July 7-9.

Processed SOHO/EIT 284 image at 01:06 UTC on July 6. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to active on July 6 due to a high speed stream from CH230. Mostly quiet conditions are likely on July 7-9. Effects from CH231 could be noticed on July 10-12.

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 fair. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Radio Cristal del Uruguay and Radio Vibración were both audible. Stations from Brazil dominated on other frequencies, on 1390 kHz there were several stations including Rádio Globo while Rádio Globo Londrina was noted on 1400 kHz.

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
10897 2006.06.25     N06W62     plage
10898 2006.06.28 6 7 S08W28 0430 CKI classification was CKO at midnight
10899 2006.07.05 2 6 S05E69 0090 DRO formerly region S667
classification was DSO at midnight
S666 2006.06.28     N05W69     plage
Total spot count: 8 13  
SSN: 28 33  

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 86.2 (1) 5.7 (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]