Last major update issued on March 26, 2010 at 03:55 UTC.
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The geomagnetic field was quiet on March 25. Solar wind speed ranged between 287 and 413 km/s, after noon under the influence of a weak low speed coronal hole stream.
Solar flux measured at 20h UTC on 2.8 GHz was 87.6. The planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 4.8). Three hour interval K indices: 11012221 (planetary), 12012311 (Boulder).
The background x-ray flux is at the class A7 level.
At midnight there were 2 spotted regions on the visible solar disk.
Region 11057 changed somewhat with increasing separation between the
opposite polarity spots. There's still a chance of C flares.
New region 11058 emerged in the northwest quadrant.
March 23-25: No obvious Earth directed CMEs were observed in LASCO or STEREO images.
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 coronal hole (CH397) in the northern hemisphere will probably rotate into an Earth facing position on March 27.
Processed SOHO/EIT 195 image at 02:48 UTC on March 25. 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 poor. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet on March 26-29. On March 30-31 there's a chance of unsettled intervals due to effects from CH397.
|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:||5||7|
|Month||Average measured solar flux||International sunspot number (SIDC)||Smoothed sunspot number||Average ap
cycle 23 sunspot max.
|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||(6.4 predicted, +1.6)||3.88 / 3.61|
|2009.10||72.6||4.6||(8.3 predicted, +1.9)||3.66 / 3.56|
|2009.11||73.6||4.2||(10.3 predicted, +2.0)||2.45 / 2.63|
|2009.12||76.7||10.6||(12.4 predicted, +2.1)||1.41 / 1.92|
|2010.01||81.1||13.1||(15.0 predicted, +2.6)||2.93 / 3.07|
|2010.02||84.7||18.6||(17.9 predicted, +2.9)||4.15 / 4.61|
|2010.03||83.1 (1)||19.1 (2)||(21.1 predicted, +3.2)||(4.59)|
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/SWPC) sunspot number. 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 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.