Last major update issued on April 5, 2010 at 04:50 UTC. Minor update posted at 10:40 UTC.
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[Solar cycles 21-23 (last update October 4, 2007)]
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[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update October 4, 2007)]
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[Archived reports (last update April 2, 2010)]
The geomagnetic field was quiet to active on April 4. Solar wind speed ranged between 453 and 538 km/s under the influence of a high speed coronal hole stream.
Solar flux measured at 20h UTC on 2.8 GHz was 78.7. The planetary A index was 13 (STAR Ap - based on the mean of three hour interval ap indices: 13.0). Three hour interval K indices: 33412234 (planetary), 33412223 (Boulder).
The background x-ray flux is at the class A5 level.
At midnight there were 2 spotted regions on the visible solar disk.
Region 11059 decayed quickly and could become spotless today.
New region 11060 rotated into view at the northeast limb on April 3 and was numbered the next day by NOAA/SWPC.
Updated added at 09:15 UTC on April 5: The CME observed on April 3 was much faster than initial velocity observations indicated. A strong solar wind shock was observed at SOHO at 07:59 UTC, just 46 hours after the LDE in region 11059 with solar wind abruptly increasing to near 700 km/s. GOES observed a strong sudden impulse and minor to major geomagnetic storming is likely today.
Updated added at 10:40 UTC: Severe geomagnetic storming is currently in progress. The 3 hour ap index reached 132 (K index 7) during the 07-10 UTC interval.
April 2 and 4: No obvious Earth directed CMEs were observed in LASCO or
April 3: A long duration event in region 11059 was associated with at least a partial halo CME.
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 (CH398) in the northern hemisphere was in an Earth facing position on April 3-4.
Processed SOHO/EIT 195 image at 23:36 UTC on April 4. 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 fair.
The geomagnetic field is expected to be quiet to active on April 5-8 due to CME effects (April 6-7) and high speed coronal hole streams.
|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
|11057||2010.03.23||3||N16W84||0090||HSX||rotated out of view|
|11059||2010.03.24||3||3||S23W28||0030||HSX||classification was AXX at midnight, area 0000|
|11060||2010.04.03||4||7||N24E58||0090||DRO||classification was DAO at midnight|
|Total spot count:||10||10|
|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||(7.4 predicted, +1.3)||3.66 / 3.56|
|2009.11||73.6||4.2||(8.9 predicted, +1.5)||2.45 / 2.63|
|2009.12||76.7||10.6||(10.8 predicted, +1.9)||1.41 / 1.92|
|2010.01||81.1||13.1||(12.6 predicted, +1.8)||2.93 / 3.07|
|2010.02||84.7||18.6||(14.7 predicted, +2.1)||4.15 / 4.61|
|2010.03||83.4||15.4||(17.1 predicted, +2.4)||4.58|
|2010.04||77.9 (1)||4.0 (2)||(19.4 predicted, +2.3)||(11.28)|
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.