Solar Terrestrial Activity Report

Last major update issued on July 11, 2005 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 July 2, 2005)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update July 2, 2005)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update July 2, 2005)]
[Historical solar and geomagnetic data charts 1954-2004 (last update February 1, 2005)]
[Archived reports (last update July 2, 2005)]

Recent activity

The geomagnetic field was active to major storm on July 10. Solar wind speed ranged between 342 and 623 (all day average 446) km/sec. A solar wind shock was observed at SOHO at 02:56 UTC, this was the arrival of one of the CMEs observed on July 7. Solar wind speed increased abruptly from 350 to 416 km/sec. The interplanetary magnetic field swung fully and very strongly southwards after 11h UTC. This caused minor to major geomagnetic storming with severe storming at high latitudes for the remainder of the day.

Solar flux measured at 20h UTC on 2.8 GHz was 101.8. The planetary A index was 47 (STAR Ap - based on the mean of three hour interval ap indices: 47.0).
Three hour interval K indices: 44556555 (planetary), 44545454 (Boulder).

The background x-ray flux is at the class B3 level.

At midnight there were 3 spotted regions on the visible solar disk. The solar flare activity level was low. A total of 3 C class events was recorded during the day.

Region 10783 rotated out of view at the southwest limb.  Flare: C9.9 at 15:16 UTC.
Region 10786 decayed in the northern spot section while some development was observed in the southernmost spot section. There is minor, if any, separation between the opposite polarity areas in the the southern central part. A minor M class flare is possible. Flares: C1.6 at 05:20 and C1.4 at 21:42 UTC.
Region 10788 decayed slowly and quietly.
Region 10789 decayed slowly and quietly.

Coronal mass ejections (CMEs)

July 10: No obvious fully or partly Earth directed CMEs were observed during the day..
July 9
: The M2 event in region 10786 produced a full halo CME. This CME was first observed in LASCO C3 images at 23:18 UTC.
July 8
: The C1 long duration event in region 10786 during the afternoon was apparently associated with a very faint partial halo CME. This CME was observed in LASCO C3 images during the evening and early on July 9.

Coronal holes

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

No obvious coronal holes are currently in or near Earth facing positions.

Processed SOHO/EIT 284 image at 01:06 UTC on July 11. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to active on July 11. The CME observed late on July 9 will probably reach Earth early on July 12 and cause unsettled to major storm conditions. Quiet to active is likely on July 13 becoming quiet on July 14-16.

Coronal holes (1) Coronal mass ejections (2) M and X class flares (3)
Coronal hole indicator CME indicator M and X class flare indicator

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) Material from a CME is likely to impact 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 unusable. Propagation along long distance north-south paths is poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay. Only a few stations from Argentina (950 kHz had the best signal), Brazil and Uruguay were audible on other frequencies.

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
10784 2005.06.29     N16W77     plage
10786 2005.07.01 27 24 N10W43 0330 DAC beta-gamma
10788 2005.07.02 7 1 S05W37 0070 HSX  
10789 2005.07.03 14 10 N17E01 0150 EAI classification was DSO at midnight
S567 2005.07.03     S07W28     plage
Total spot count: 48 35  
SSN: 78 65  

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)
2004.05 99.8 41.5 43.8 (-1.7)
2004.06 97.4 43.2 41.6 (-2.2)
2004.07 119.1 51.1 40.2 (-1.4)
2004.08 109.6 40.9 39.2 (-1.0)
2004.09 103.1 27.7 37.5 (-1.7)
2004.10 105.9 48.0 35.9 (-1.6)
2004.11 113.2 43.5 35.3 (-0.6)
2004.12 94.5 17.9 35.2 (-0.1)
2005.01 102.2 31.3 (34.6 predicted, -0.6)
2005.02 97.2 29.1 (33.3 predicted, -1.3)
2005.03 89.9 24.8 (31.6 predicted, -1.7)
2005.04 86.0 24.4 (29.7 predicted, -1.9)
2005.05 99.3 42.6 (27.2 predicted, -2.5)
2005.06 93.7 39.3 (25.7 predicted, -1.5)
2005.07 118.5 (1) 46.7 (2) (24.7 predicted, -1.0)

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]