Solar Terrestrial Activity Report

Last major update issued on August 9, 2004 at 04:30 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update August 2, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update August 2, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update August 2, 2004)]
[Historical solar and geomagnetic data charts 1954-2004 (last update April 28, 2004)]
[Archived reports (last update August 1, 2004)]

Recent activity

The geomagnetic field was quiet on August 8. Solar wind speed ranged between 363 and 535, gradually decreasing all day.

Solar flux measured at 20h UTC on 2.8 GHz was 104.8. The planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 6.5).
Three hour interval K indices: 22102222 (planetary), 12112221 (Boulder).

The background x-ray flux is at the class B4 level.

At midnight there were 4 spotted regions on the visible disk. The solar flare activity level was low. A total of 2 C class events were recorded during the day.

Region 10655 decayed slowly and quietly.
Region 10656 developed quickly in the trailing positive polarity area. A magnetic delta structure formed in the center of the region. There is an increasing possibility of a minor M class flare. Flares: C2.7 at 17:24 and C1.0 at 23:09 UTC.
Region 10657 was quiet and stable.

Spotted regions not numbered by NOAA/SEC:
[S443] This region rotated partly into view at the northeast limb late on August 8.

Coronal mass ejections (CMEs)

August 6-7: No obviously Earth directed CMEs were detected in LASCO images.
August 8: A bright full halo CME was observed in LASCO C3 images starting at 09:42 UTC. The leading front was first observed off of the east limb and the south pole. The source of this event was likely about 5-6 days behind the southeast limb.

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

The northernmost extension of a coronal hole (CH108) in the southern hemisphere may have been in a geoeffective position on August 7. The southernmost part of a large, poorly defined coronal hole (CH109) in the northern hemisphere will be in a geoeffective position on August 8-9.

Processed SOHO/EIT 284 image at 01:06 UTC on August 9. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to unsettled on August 9 with conditions becoming quiet to active on August 10-12 due to effects from coronal holes CH108 and CH109.

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 poor to fair. Propagation along long distance north-south paths is very good. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant stations tonight: Several stations from Brazil noted. On other frequencies, particularly above 1200 kHz, propagation was exceptionally good towards Brazil with most frequencies having a mess of several stations, occasionally with one station dominating. Above 1600 kHz several stations from the USA were noted before 03h UTC, 1510 WWZN could be heard at times as well below a couple of unidentified Brazilians.

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
10655 2004.07.30 15 8 S10W54 0150 EAI classification was CAI,
area 0130 at midnight
10656 2004.08.06 20 27 S12E45 0290 EAO beta-gamma-delta
classification was DKC,
area 0330 at midnight
10657 2004.08.06 1 1 N11E51 0040 HAX  
10658 2004.08.07 1   S05E38 0010 AXX spotless
S441 emerged on
    N16W52     plage
S443 visible on
  1 N18E81 0020 HSX  
Total spot count: 37 37
SSN: 77 77

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)
2003.06 129.3 77.4 65.0 (-2.6)
2003.07 127.7 83.3 61.8 (-3.2)
2003.08 122.1 72.7 60.1 (-1.7)
2003.09 112.2 48.7 59.6 (-0.5)
2003.10 151.7 65.5 58.2 (-1.4)
2003.11 140.8 67.3 56.8 (-1.4)
2003.12 114.9 46.5 54.8 (-2.0)
2004.01 114.1 37.7 52.0 (-2.8)
2004.02 107.0 45.8 (49.1 predicted, -2.9)
2004.03 112.0 49.1 (46.5 predicted, -2.6)
2004.04 101.2 39.3 (44.3 predicted, -2.2)
2004.05 99.8 41.5 (41.0 predicted, -3.3)
2004.06 97.4 43.2 (38.2 predicted, -2.8)
2004.07 119.1 51.0 (36.3 predicted, -1.9)
2004.08 89.9 (1) 13.8 (2) (34.9 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% less.

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]