Solar Terrestrial Activity Report

Last major update issued on June 6, 2004 at 04:55 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update June 2, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update June 2, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update June 2, 2004)]
[Historical solar and geomagnetic data charts 1954-2004 (last update April 28, 2004)]
[Archived reports (last update May 30, 2004)]

Recent activity

The geomagnetic field was quiet to unsettled on June 5. Solar wind speed ranged between 421 and 478 km/sec. Solar wind speed increased slowly after 17h UTC and another coronal hole flow is currently influencing the geomagnetic field. Active conditions have been observed early on June 6.

Solar flux measured at 20h UTC on 2.8 GHz was 84.5. The planetary A index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 11.5).
Three hour interval K indices: 33133333 (planetary), 33122323 (Boulder).

The background x-ray flux is at the class A7 level.

At midnight there were 3 spotted regions on the visible disk. The solar flare activity level was very low. No C class events were recorded during the day.

Region 10621 decayed slowly and quietly.
New region 10626 emerged in the northeast quadrant on June 4 and was numbered the next day by SEC. The region decayed slowly on June 5 and could soon become spotless.
New region 10627 emerged in the southeast quadrant on June 4 and was numbered the next day by SEC. The region was mostly unchanged on June 5.

Coronal mass ejections (CMEs)

June 3-5: No fully or partly Earth directed CMEs observed. A large full halo CME was observed during the morning of June 4, its source was a few days behind the west 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

 A recurrent trans equatorial coronal hole (CH99) was in a geoeffective position on May 30-31. A small recurrent coronal hole (CH100) in the northern hemisphere was in a geoeffective position on June 4.

Processed SOHO/EIT 284 image at 19:05 UTC on June 5. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to active on June 6-7 due to coronal hole effects and quiet to unsettled on June 8-9.

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 very poor. Propagation along long distance north-south paths is good to excellent. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay.  Radio Vibración (Venezuela) was noted occasionally. Good to excellent propagation towards Brazil was observed from well before local sunrise to nearly one hour after local sunrise. Rádio Inconfidência on 880 kHz had an unusually good signal with other strong stations noted on 740, 760, 840, 860, 930, 1010 kHz. Lots of frequencies had weaker signals from Brazil. Argentina was noted on a few frequencies with the Cordoba station on 700 kHz heard well. A few USA stations had weak signals on frequencies above 1600 kHz and WWZN Boston on 1510 kHz crossed the Atlantic with a fair 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
10621 2004.05.29 11 8 S14W28 0030 CAO  
10622 2004.05.30     S09W06     plage
10623 2004.06.01     N08W74     plage
10624 2004.06.01 2   S08E11 0010 AXX spotless
10625 2004.06.03     S12W82     plage
10626 2004.06.05 3 2 N05W06 0020 CSO formerly region S411
classification was AXX
at midnight, area 0000
10627 2004.06.05 3 3 S08E30 0020 HAX formerly region S412
classification was HSX
at midnight
S409 emerged on
    S01W44     plage
Total spot count: 19 13
SSN: 59 43

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)
2003.05 115.7 55.2 67.6 (-2.5)
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 60.0 (-1.8)
2003.09 112.2 48.7 59.5 (-0.5)
2003.10 151.7 65.5 58.1 (-1.4)
2003.11 140.8 67.3 56.7 (-1.4)
2003.12 114.9 46.5 (54.4 predicted, -2.3)
2004.01 114.1 37.2 (50.5 predicted, -3.9)
2004.02 107.0 46.0 (46.2 predicted, -4.3)
2004.03 112.0 48.9 (43.5 predicted, -2.7)
2004.04 101.2 39.3 (41.4 predicted, -2.1)
2004.05 99.8 41.5 (38.2 predicted, -3.2)
2004.06 88.9 (1) 11.0 (2) (35.3 predicted, -2.9)

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]