Solar Terrestrial Activity Report

Last major update issued on June 7, 2006 at 02:00 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update April 1, 2006)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update April 1, 2006)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update April 1, 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 6. Solar wind speed ranged between 309 and 644 km/s (all day average 423 km/s - increasing 78 km/s from the previous day), under the increasing influence of a high speed stream from CH227 after 05h UTC.

Solar flux measured at 20h UTC on 2.8 GHz was 78.0. The planetary A index was 23 (STAR Ap - based on the mean of three hour interval ap indices: 22.8).
Three hour interval K indices: 22443454 (planetary), 12443434 (Boulder).

The background x-ray flux is at the class A5 level.

At midnight there were 2 spotted regions on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day.

Region 10892 was quiet and mostly unchanged.
New region 10893 emerged in the southeast quadrant. C flares are possible.

Coronal mass ejections (CMEs)

June 4-6: No partly or fully Earth directed CMEs were observed in very incomplete LASCO imagery.

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 (CH227) in the northern hemisphere was in an Earth facing position on June 4-6.

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 unsettled to minor storm on June 7 and quiet to active on June 8-9.

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. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Radio Cristal del Uruguay was observed with a weak signal. Only a few other frequencies (1390, 1510 and 1540 kHz) had audible stations.

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
10887 2006.05.26     S13W83     plage
10891 2006.05.30     S14W72     plage
10892 2006.06.04 13 19 S07E41 0250 EKI area was 0350 at midnight
10893 2006.06.06 3 5 S03E64 0030 CAO classification was DAO at midnight, area 0080
Total spot count: 16 24  
SSN: 36 44  

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 76.7 (1) 2.9 (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]