Solar Terrestrial Activity Report

Last major update issued on June 15, 2006 at 03:20 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 unsettled on June 14. Solar wind speed ranged between 337 and 561 km/s (all day average 361 km/s (incomplete data) - increasing 12 km/s over the previous day). A high speed stream from CH228 caused a slow increase in solar wind speed after 08h UTC and a more rapid increase after 20h UTC.

Solar flux measured at 20h UTC on 2.8 GHz was 75.3. The planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 7.1).
Three hour interval K indices: 21111223 (planetary), 22122023 (Boulder).

The background x-ray flux is at the class B1 level.

At midnight there was 1 spotted region on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day. A rapidly developing region at and just behind the west limb caused an increase in the background xray flux.

Region 10892 was quiet and stable and will rotate out of view at the southwest limb today.

Coronal mass ejections (CMEs)

June 12-14: 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 19:06 UTC on May 26. 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 15 and quiet to unsettled on June 16-17.

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 fair. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Radio Cristal del Uruguay had company from Radio Vibración (Venezuela) although signals were fairly low for both. On other frequencies most of the TA stations heard were from Brazil and Argentina.

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 1 S07W70 0100 HSX classification was HSX at midnight
location: S07W73
10893 2006.06.06 2   S01W43 0010 AXX spotless
10894 2006.06.11 2   S07W04 0010 AXX spotless
Total spot count: 5 1  
SSN: 35 11  

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 77.0 (1) 14.2 (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]