Solar Terrestrial Activity Report

Last major update issued on June 3, 2010 at 04:15 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-24 (last update May 26, 2010)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update October 4, 2007)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update October 4, 2007)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports (last update April 2, 2010)]

Recent activity

The geomagnetic field was quiet to unsettled on June 2. Solar wind speed ranged between 423 and 549 km/s under the diminishing influence of a high speed stream associated with CH406.

Solar flux measured at 20h UTC on 2.8 GHz was 74.0. The planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 6.5). Three hour interval K indices: 23002213 (planetary), 23111222 (Boulder).

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

At midnight there was 1 spotted region on the visible solar disk.

Region 11076 developed significantly and could produce C flares.

Coronal mass ejections (CMEs)

June 1-2: No obvious Earth directed CMEs were observed in LASCO or STEREO images.
May 31: A filament eruption was observed in the northwest quadrant just east of CH406 starting at 19:36 UTC. Although a CME was observed, it appears to be fairly narrow in extent.

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 (CH406) in the northern hemisphere was in an Earth facing position on May 28.

Processed SOHO/EIT 195 image at 00:00 UTC on June 3. The darkest areas on the solar disk are likely coronal holes.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is poor. Propagation on long distance northeast-southwest paths is fair.

Forecast

The geomagnetic field is expected to be mostly quiet on June 3-5. Some unsettled intervals are possible on June 4 should the CME observed on May 31 reach Earth.

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.

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/SWPC. 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 SWPC or where SWPC has observed no spots. SWPC active region numbers in the table below and in the active region map above are the historic SWPC/USAF numbers.

Active region Date numbered SWPC
spot
count
STAR
spot
count
Location at midnight Area SWPC
Classification
Comment
11073 2010.05.29     N12W17     plage
11075 2010.05.29     S19W58     plage
11076 2010.05.31 8 17 S19W22 0040 DAI area was 0110 at midnight
S772 2010.06.01     S33W08     plage
Total spot count: 8 17  
SSN: 18 27  

Monthly solar cycle data

Month Average measured solar flux International sunspot number (SIDC) Smoothed sunspot number Average ap
(3)
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)  
2008.07 65.7 (SF minimum) 0.5 2.8 (-0.4)  
2008.12 69.2 0.8 1.7 (-)
sunspot minimum
3.25
2009.03 69.2 0.7 2.0 (+0.1) 4.85
2009.04 69.7 0.8 2.2 (+0.2) 4.52
2009.05 70.5 2.9 2.3 (+0.1) 4.75
2009.06 68.6 2.9 2.7 (+0.4) 5.22
2009.07 68.2 3.2 3.6 (+0.9) 5.49 / 4.55
2009.08 67.3 0.0 4.8 (+1.2) 5.70 / 4.89
2009.09 70.5 4.3 6.1 (+1.3) 3.88 / 3.61
2009.10 72.6 4.8 7.0 (+0.9) 3.66 / 3.56
2009.11 73.6 4.1 7.6 (+0.6) 2.45 / 2.63
2009.12 76.7 10.8 (8.2 predicted, +0.6) 1.41 / 1.92
2010.01 81.1 13.1 (9.2 predicted, +1.0) 2.93 / 3.07
2010.02 84.7 18.6 (10.7 predicted, +1.5) 4.15 / 4.61
2010.03 83.4 15.4 (12.5 predicted, +1.8) 4.58 / 4.65
2010.04 75.9 7.9 (14.1 predicted, +1.6) 10.22 / 10.24
2010.05 73.8 8.8 (15.4 predicted, +1.3) 9.18
2010.06 73.4 (1) 1.1 (2) (16.9 predicted, +1.5) (9.31)

1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz.
2) Current impact on the monthly SSN based on the Boulder (NOAA/SWPC) sunspot number (accumulated daily sunspots / month days). The official international sunspot number is typically 30-50% lower.
3) Running average based on the daily SWPC ap indices. Values in red are based on the official NGDC ap indices.

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.