Solar Terrestrial Activity Report

Last major update issued on June 14, 2004 at 03:30 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 June 7, 2004)]

Recent activity

The geomagnetic field was quiet on June 13. Solar wind speed ranged between 294 and 369 km/sec. A mild solar wind disturbance began at approximately 17h UTC. The interplanetary magnetic field was weakly to moderately southwards for the remainder of the day. While this disturbance was not reflected in the planetary A index, the main radio propagation direction became more southerly.

Solar flux measured at 20h UTC on 2.8 GHz was 95.2. The planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 5.1).
Three hour interval K indices: 10112222 (planetary), 21213323 (Boulder).

The background x-ray flux is at the class B3 level.

At midnight there were 4 spotted regions on the visible disk. The solar flare activity level was moderate. A total of 1 C and 1 M class events was recorded during the day.

Region 10632 was quiet and stable.
New region 10633 emerged in the southeast quadrant on June 12 and was numbered the next day by SEC. The region decayed slowly on June 13 and could soon become spotless.
New region 10634 rotated partly into view at the northeast limb on June 12 and was numbered the next day by SEC. The region has a magnetic delta structure in the trailing spot section and could produce further M class flares. Flares: C4.1 at 04:44 and a long duration M1.0 event peaking at 11:56 UTC.

Spotted regions not numbered by NOAA/SEC:
[S418] This region rotated partly into view at the southeast limb late on June 13. The region has been displaying some activity at the limb and could produce C flares. Location at midnight: S08E83.

Coronal mass ejections (CMEs)

June 11-13: No fully or partly 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 recurrent coronal hole (CH101) in the southern hemisphere was in a geoeffective position on June 12. A recurrent trans equatorial coronal hole (CH102) will likely rotate into a geoeffective position on June 15.

Processed SOHO/EIT 284 image at 01:05 UTC on June 14. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to unsettled most of  June 14 becoming unsettled to active late in the day and on June 15 due to a high speed stream from coronal hole CH101. Quiet to unsettled is expected for June 16-17 with quiet to active likely on June 18 due to a high speed stream from coronal hole CH102.

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 along long distance north-south paths is poor. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay. Radio Vibración (Venezuela) was observed at an after local sunrise. On other frequencies a few stations from Brazil (740, 980 and 1440 kHz) had fairly good signals. 1510 WWZN was the only station from North America with a weak signal at 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
10627 2004.06.05     S09W74     plage
10628 2004.06.07     S09W63     plage
10629 2004.06.07     S05W56     plage
10630 2004.06.07     N14W22     plage
10631 2004.06.09 5   S10W10 0020 CAO spotless
10632 2004.06.10 1 1 S11E26 0070 HSX  
10633 2004.06.13 2 1 S05E37 0010 AXX formerly region S416
10634 2004.06.13 7 15 N12E73 0120 DAO beta-gamma-delta
formerly region S417
classification was DAI
at midnight, area 0300
S414 emerged on
    S03W64     plage
S418 visible on
  1 S08E83 0040 HSX  
Total spot count: 15 18
SSN: 55 58

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 87.8 (1) 26.5 (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]