Solar Terrestrial Activity Report

Last major update issued on November 1, 2004 at 03:55 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 30, 2004)]

Recent activity

The geomagnetic field was quiet to unsettled on October 31. Solar wind speed ranged between 400 and 468 km/sec under the influence of a fairly low speed stream from coronal hole CH121.

Solar flux measured at 17h UTC on 2.8 GHz was 139.2. The planetary A index was 10 (STAR Ap - based on the mean of three hour interval ap indices: 9.5).
Three hour interval K indices: 32123223 (planetary), 33122323 (Boulder).

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

At midnight there were 6 spotted regions on the visible solar disk. The solar flare activity level was moderate. A total of 5 C and 2 M class events was recorded during the day.

Region 10687 decayed further and lost the remaining penumbra. Only a single small spot is visible and the region will rotate out of view at the northeast limb today. 
Region 10689 decayed slowly and quietly.
Region 10690 decayed with the single penumbra losing area. A fw small spots emerged in the southern part of the region.
Region 10691 decayed significantly with the main penumbra losing quite a bit of its area and several small trailing spots disappearing. There is still a weak magnetic delta at the southern end of the main penumbra. Further minor M class flares are possible. Flares: C1.7 at 00:55, M1.1 at 02:26, M2.3 at 05:32 (with associated weak type IV and moderate type II radio sweeps), C1.3 at 13:21, C1.5 at 19:59 and C7.0 at 21:27 UTC.
Region 10693 developed further adding penumbra, however, the region is currently not very complex magnetically. A minor M class flare is possible. Flare: C1.0 at 07:21 UTC.
Region 10695 was quiet and stable.

Coronal mass ejections (CMEs)

October 30: It is likely that several CMEs were associated with M and X class flares in region region 10691 this day. Most of these could reach Earth on November 1 and 2. Unfortunately LASCO images were not available for the parts of the day when flaring in region 10691 was most intense. With images back in the afternoon only a single full halo CME was observed, this was after the major M5.9 event.
October 29 and 31
: No obviously Earth directed CMEs 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 trans equatorial coronal hole (CH122) was in a geoeffective position on October 30-31.

Processed SOHO/EIT 284 image at 01:06 UTC on November 1. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to major storm on November 1 and unsettled to minor storm on November 2. Unsettled to active is likely on November 3-4 due to effects from coronal hole CH122.

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 to fair. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant stations tonight: Radio Vibración (Venezuela) and Radio Cristal del Uruguay. On other frequencies propagation was best towards the Canadian Atlantic provinces, Boston, Flroida, Cuba, Puerto Rico and Venezuela. Post sunrise propagation on October 31 was interesting with some east coast North American stations audible until 09h UTC, well over 2 hours after local sunrise.

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
10687 2004.10.19 4 1 N12W80 0060 CAO classification was HRX
at midnight, area 0010
10689 2004.10.21 1 1 N11W57 0040 HSX area was 0020
at midnight
10690 2004.10.22 7 7 S02W41 0040 DAO classification was CAO
at midnight
10691 2004.10.23 23 14 N13W42 0270 DAC beta-gamma-delta
classification was DAO
at midnight
10692 2004.10.24     S19W67     plage
10693 2004.10.27 50 39 S16E22 0760 FKC beta-gamma
10694 2004.10.28 4   N14W16 0010 AXX spotless
10695 2004.10.30 4 4 S15E55 0130 DAO area was 0070
at midnight
S467 emerged on
    S08W78     plage
Total spot count: 93 66
SSN: 163 126

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)
2004.10 105.9 (1) 77.9 (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]