Last major update issued on June 1, 2010 at 04:10 UTC.
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[Solar cycles 21-24 (last update May 26, 2010)]
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[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update October 4, 2007)]
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The geomagnetic field was quiet to active on May 31. Solar wind speed ranged between 495 and 710 km/s under the influence of a high speed stream associated with CH406.
Solar flux measured at 20h UTC on 2.8 GHz was 72.0. The planetary A index was 16 (STAR Ap - based on the mean of three hour interval ap indices: 15.1). Three hour interval K indices: 33433323 (planetary), 24433323 (Boulder).
The background x-ray flux is at the class A4 level.
At midnight there was 1 spotted region on the visible solar disk.
New region 11076 emerged in the southeast quadrant.
May 29-30: No obvious Earth directed CMEs were observed in LASCO or
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 and not Earth directed.
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 1. The darkest areas on the solar disk are likely coronal holes.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is very poor. Propagation on long distance northeast-southwest paths is fair.
The geomagnetic field is expected to be quiet to active on June 1 due to a high speed stream from CH406. Quiet conditions are likely on June 2-3.
|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.
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
|Location at midnight||Area||SWPC
|Total spot count:||9||4|
|Month||Average measured solar flux||International sunspot number (SIDC)||Smoothed sunspot number||Average ap
cycle 23 sunspot max.
|2008.07||65.7 (SF minimum)||0.5||2.8 (-0.4)|
|2009.07||68.2||3.5||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||4.2||6.1 (+1.3)||3.88 / 3.61|
|2009.10||72.6||4.6||7.0 (+0.9)||3.66 / 3.56|
|2009.11||73.6||4.2||(7.7 predicted, +0.7)||2.45 / 2.63|
|2009.12||76.7||10.6||(8.9 predicted, +1.2)||1.41 / 1.92|
|2010.01||81.1||13.1||(10.2 predicted, +1.3)||2.93 / 3.07|
|2010.02||84.7||18.6||(11.8 predicted, +1.6)||4.15 / 4.61|
|2010.03||83.4||15.4||(13.7 predicted, +1.9)||4.58 / 4.65|
|2010.04||75.9||7.9||(15.3 predicted, +1.8)||10.22 / 10.24|
|2010.05||73.8 (1)||19.6 (2)||(16.6 predicted, +1.3)||(9.18)|
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.