Solar Terrestrial Activity Report

Last major update issued on July 16, 2005 at 04:50 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 quiet on July 15. Solar wind speed ranged between 357 and 460 (all day average 423) km/sec. A minor solar wind shock was observed at 02:42 UTC on July 16. It is uncertain if this was the arrival of the CME observed on July 12 or the one seen on July 13.

Solar flux measured at 20h UTC on 2.8 GHz was 87.2. The planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 6.3).
Three hour interval K indices: 12211222 (planetary), 02212122 (Boulder).

The background x-ray flux is at the class B7 level.

At midnight there was 1 spotted region on the visible solar disk. The solar flare activity level was low. A total of 6 C class events was recorded during the day.

Region 10786 was fairly active during the day behind the northwest limb, however, flare intensity was not at the level of the preceding day. Flares: C1.6 at 02:00, C1.6 at 03:04, very long duration C2.3 event peaking at 14:45 and long duration C7.3 peaking at 23:25 UTC.

Spotted regions not numbered or wrongly numbered by NOAA/SEC:
[S570] This region emerged in the southwest quadrant on July 13 just west of region 10790. The region developed further on July 15. The opposite polarity areas are poorly separated near the main trailing penumbra. Location at midnight: S12W68. Flares: C4.0 at 11:46 and C1.8 at 19:44 UTC.

Coronal mass ejections (CMEs)

July 13: A large, wide and fast full halo CME was observed during the afternoon and early evening in LASCO C3 images after the M5 long duration event in region 10786.
July 14: A large, fast and very wide full halo CME was observed in LASCO C3 images after the X1 event in region 10786.
July 15: No obvious partly or fully Earth directed CMEs were observed.

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

A recurrent trans equatorial coronal hole (CH175) will rotate into an Earth facing position on July 17-18.

Processed SOHO/EIT 284 image at 01:06 UTC on July 16. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to minor storm on July 16-17 due to CME effects. Quiet to unsettled is likely on July 18-19.

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 very poor. Propagation along long distance north-south paths is poor to fair. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay and Radio Vibración (Venezuela). Several weak stations with audio (from Argentina, Brazil and Uruguay) were noted on frequencies above 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
10789 2005.07.03 1   N17W59 0020 HSX spotless
10790 2005.07.13 17   S10W61
(SEC: S10W67)
0110 DSI region is spotless, SEC unfortunately did not observe the presence of two regions on July 13 and when region 10790 lost its spots, the region number was reused
S569 2005.07.12     N06E16     plage
S570 2005.07.13   8 S12W69 0120 DAO beta-gamma
SEC has this as region 10790
Total spot count: 18 8  
SSN: 38 18  

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)
2005.07 109.5 (1) 55.6 (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]