Solar Terrestrial Activity Report

Last major update issued on June 16, 2006 at 04:15 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update June 7, 2006)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update June 7, 2006)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update June 7, 2006)]
[Historical solar and geomagnetic data charts 1954-2005 (last update March 3, 2006)]
[Archived reports (last update June 5, 2006)]

Recent activity

The geomagnetic field was quiet to minor storm on June 15. Solar wind speed ranged between 523 and 681 km/s (all day average 581 km/s - increasing 185 km/s over the previous day (revised average then was 396 km/sec)). A high speed stream from CH228 dominated the solar wind all day.

Solar flux measured at 20h UTC on 2.8 GHz was 76.4. The planetary A index was 28 (STAR Ap - based on the mean of three hour interval ap indices: 27.6).
Three hour interval K indices: 24553334 (planetary), 24663334 (Boulder).

The background x-ray flux is at the class A6 level.

At midnight there were 2 spotted regions on the visible solar disk. The solar flare activity level was low. A total of 2 C class events was recorded during the day from the new region which is now well behind the southwest limb. A C2.6 flare was recorded at 04:31 and a C1.4 flare at 08:23 UTC.

Spotted regions not numbered by NOAA/SEC:
[S662] This region emerged in the northeast quadrant on June 15. Location at midnight: N02E36.
[S663] A new region emerged in the southeast quadrant on June 15. Location at midnight: S10E53.

Coronal mass ejections (CMEs)

June 13-15: No partly or fully Earth directed CMEs were observed in LASCO imagery.

Coronal holes

Coronal hole history (since late October 2002)
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago

A recurrent coronal hole (CH228) in the southern hemisphere was in an Earth facing position on June 12-13.

Processed SOHO/EIT 284 image at 23:18 UTC on June 15. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled with a chance of isolated active intervals on June 16 and quiet to unsettled on June 17. Mostly quiet conditions are likely on June 18-20.

Coronal holes (1) Coronal mass ejections (2) M and X class flares (3)

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) Effects from a CME are likely to be observed at 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.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is very poor. Propagation on long distance northeast-southwest paths is poor to fair. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Radio Vibración (Venezuela) had a good signal for a few minutes just after LSR, otherwise several weak signals were heard on this frequency. Other TA frequencies had weaker than average signals mainly from Brazil and Uruguay.

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
spot
count
STAR
spot
count
Location at midnight Area Classification Comment
10892 2006.06.04 1   S06W85 0080 HSX rotated out of view
10893 2006.06.06     S01W56     plage
10894 2006.06.11     S06W18     plage
S662 2006.06.15   2 N02E36 0010 AXX  
S663 2006.06.15   5 S10E53 0010 BXO  
Total spot count: 1 7  
SSN: 11 27  

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)
2005.04 86.0 24.2 31.6 (-1.9)
2005.05 99.3 42.7 28.9 (-2.7)
2005.06 93.7 39.3 28.8 (-0.1)
2005.07 96.4 40.1 29.1 (+0.3)
2005.08 90.5 36.4 27.4 (-1.7)
2005.09 91.1 21.9 25.8 (-1.6)
2005.10 77.0 8.5 25.5 (-0.3)
2005.11 86.3 18.0 24.9 (-0.6)
2005.12 90.7 41.2 (22.8 predicted, -2.1)
2006.01 83.4 15.4 (20.1 predicted, -2.7)
2006.02 76.5 4.7 (17.1 predicted, -3.0)
2006.03 75.4 10.8 (15.1 predicted, -2.0)
2006.04 89.0 30.2 (14.4 predicted, -0.7)
2006.05 80.9 22.2 (13.5 predicted, -0.9)
2006.06 76.9 (1) 14.6 (2) (11.4 predicted, -2.1)

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% lower.

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]