Solar Terrestrial Activity Report

Last major update issued on October 30, 2004 at 02:40 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update October 2, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update October 2, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update October 2, 2004)]
[Historical solar and geomagnetic data charts 1954-2004 (last update August 28, 2004)]
[Archived reports (last update October 18, 2004)]

Recent activity

The geomagnetic field was inactive to unsettled on October 29. Solar wind speed ranged between 278 and 386 km/sec. A low speed stream from coronal hole CH121 reached Earth near 06h UTC. Since then solar wind speed has been increasing slowly. Geomagnetic effects have increased noticeably early on October 30. 

Solar flux measured at 17h UTC on 2.8 GHz was 128.8. The planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 6.9).
Three hour interval K indices: 00133231 (planetary), 01134222 (Boulder).

The background x-ray flux is at the class B5 level.

At midnight there were 8 spotted regions on the visible solar disk. The solar flare activity level was low. A total of 9 C class events was recorded during the day.

Region 10687 decayed quickly and lost many spots.
Region 10689 decayed slowly and quietly.
Region 10690 decayed slowly and quietly.
Region 10691 developed quickly as new negative polarity flux emerged immediately ahead of the single penumbra. New spots emerged and a strong magnetic delta structure has formed. The penumbral area has almost tripled. M class flares are likely. Flares: C1.1 at 21:16 and C3.1 at 23:59 UTC.
Region 10692 decayed slowly and quietly.
Region 10693 became less complex in the leading penumbra. Late in the day quick development was observed in the trailing spot section with many new spots emerging. An M class flare is possible. Flares: C1.1 at 10:55, C1.4 at 12:43, C2.4 at 14:36, C2.8 at 16:33, C3.4 at 19:22, C1.4 at 21:36 and C1.0 at 22:46 UTC.
Region 10694 developed slowly and was quiet.

Spotted regions not numbered by NOAA/SEC:
[S468] This region rotated into view at the southeast limb on October 29. C class flaring is possible. Location at midnight: S15E78.

Coronal mass ejections (CMEs)

October 28-29: No obviously Earth directed CMEs observed.
October 27: A faint, slow, full halo CME was observed in LASCO C3 images beginning at 13:42 UTC. The origin of this CME may have been in region 10691 around 09h UTC. This was the only significant frontside activity that can be related to the CME. If the CME was frontsided it could reach Earth on October 31.

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 coronal hole (CH121) in the southern hemisphere was in a geoeffective position on October 25-26. A trans equatorial coronal hole (CH122) will rotate into a geoeffective position on October 31 and November 1.

Processed SOHO/EIT 284 image at 19:06 UTC on October 29. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to active on October 30 due to effects from coronal hole CH121. Unsettled to active is possible on October 31 if the CME observed on October 27 arrive, while November 1-2 should see quiet to unsettled conditions. 

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. Propagation along long distance north-south paths is poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant stations tonight: WLAM Lewiston ME with a good signal at midnight UTC, later on propagation favored more southern signals and Radio Vibración (Venezuela) became stronger. At midnight UTC propagation was good towards North America with many stations audible. At that time short range propagation towards Europe was poor and favored signals from the south. Within an hour long range trans Atlantic propagation on westerly paths suffered while signals on southwesterly paths improved. KBRW Barrow, Alaska on 680 kHz was heard again during the afternoon of October 29 at 15:35 UTC with a good signal.

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
10684 2004.10.17 1   S04W96 0060 HAX rotated out of view
10687 2004.10.19 13 14 N12W50 0160 DAI classification was CAO
at midnight, area 0080
10689 2004.10.21 1 1 N12W30 0050 HSX  
10690 2004.10.22 3 4 N00W14 0070 HAX  
10691 2004.10.23 12 19 N13W13 0120 DAO beta-delta
classification was DKO
at midnight, area 0320
10692 2004.10.24 1 1 S18W42 0020 HSX  
10693 2004.10.27 12 23 S14E46 0590 EHI beta-gamma
classification was EKI
at midnight, area 0660
10694 2004.10.28 7 6 N17E07 0010 BXO classification was CAO
at midnight, area 0020
S467 emerged on
    S08W52     plage
S468 visible on
  7 S15E78 0070 DAO  
Total spot count: 50 75
SSN: 130 155

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)
2003.08 122.1 72.7 60.0 (-1.7)
2003.09 112.2 48.7 59.5 (-0.5)
2003.10 151.7 65.5 58.2 (-1.3)
2003.11 140.8 67.3 56.7 (-1.5)
2003.12 114.9 46.5 54.8 (-1.9)
2004.01 114.1 37.3 52.0 (-2.8)
2004.02 107.0 45.8 49.3 (-2.7)
2004.03 112.0 49.1 47.1 (-2.2)
2004.04 101.2 39.3 (44.6 predicted, -2.5)
2004.05 99.8 41.5 (40.9 predicted, -3.7)
2004.06 97.4 43.2 (38.0 predicted, -2.9)
2004.07 119.1 51.0 (36.2 predicted, -1.8)
2004.08 109.6 40.9 (34.6 predicted, -1.6)
2004.09 103.1 27.7 (32.8 predicted, -1.6)
2004.10 103.7 (1) 67.7 (2) (30.5 predicted, -2.3)

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]