Solar Terrestrial Activity Report

Last major update issued on August 1, 2005 at 05:05 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 19, 2005)]

Recent activity

The geomagnetic field was quiet to unsettled on July 31. Solar wind speed ranged between 409 and 537 (all day average 460) km/sec. Solar wind speed increased by nearly 100 km/sec from 20 to 22h UTC as a fairly weak disturbance arrived. The above 10 MeV proton flux increased slightly as well.

Solar flux measured at 20h UTC on 2.8 GHz was 109.7. The planetary A index was 9 (STAR Ap - based on the mean of three hour interval ap indices: 9.1).
Three hour interval K indices: 23213223 (planetary), 23212223 (Boulder).

The background x-ray flux is at the class B2 level.

At midnight there were 6 spotted regions on the visible solar disk. The solar flare activity level was moderate. A total of 2 C and 1 M class events was recorded during the day.

Region 10791 decayed slowly and quietly.
Region 10792 was mostly unchanged, however, the separation between the main umbrae in the trialing penumbra increased. The region remains capable of producing a major proton flare. Flares: C7.0 at 09:23 and M1.1 at 12:24 UTC.
Region 10793 decayed and could soon become spotless. SEC has combined this and region S575 into one region despite of the presence of two distinct bipolar systems.
New region 10794 rotated partly into view at the southeast limb on July 30 and was numbered the next day by SEC. Flare: C1.4 at 07:04 UTC.
New region 10795 rotated into view at the northeast limb.

Spotted regions not numbered by NOAA/SEC:
[S575] This region emerged just east of region 10793 on July 29 and developed slowly on July 30. Slow decay was observed on July 31 and the region could soon become spotless. Location at midnight: N13W15.

Coronal mass ejections (CMEs)

July 29 and 31: No obvious partly or fully Earth directed CMEs were observed.
July 30: A large and wide full halo CME was observed after the X1 flare in region 10792 early in the day. LASCO C3 images shows the CME emerging at the northeast limb at 07:00 UTC.

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 August 1. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to major storm on August 1 due to CME effects. Quiet to active is likely on August 2 becoming quiet to unsettled on August 3.

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 on 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. Propagation was uninteresting with only a few stations from Argentina noted 20-40 minutes after local sunrise. Radio Belgrano on 1510 kHz was there, however, most of the usual stations from the Buenos Aires area were either inaudible or very weak. From North America only a few stations from Newfoundland could be heard (590, 800 and 930 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
10791 2005.07.23 2 2 N12W62 0040 CAO classification was CSO at midnight, area 0050, location: N13W63
10792 2005.07.28 40 41 N12E38 0420 DKC beta-gamma-delta
location: N11E36
10793 2005.07.29 14 8 N13W16 0080 DAO classification was BXO at midnight, area 0020
SEC has combined this and region S575
location: N14W18
10794 2005.07.31 2 4 S11E73 0060 HAX formerly region S577
classification was CAO at midnight, area 0090
location: S11E70
10795 2005.07.31 2 1 N15E77 0060 HAX area was 0080 at midnight
location: N13E76
S575 2005.07.29   12 N12W15 0030 CAI  
S576 2005.07.30     N01W26     plage
Total spot count: 60 68  
SSN: 110 128  

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 96.4 (1) 68.7 (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]