Last major update issued on April 11, 2010 at 06:10 UTC. Minor update posted at 13:25 UTC.
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The geomagnetic field was very quiet on April 10. Solar wind speed ranged between 325 and 454 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 75.0. The planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 2.9). Three hour interval K indices: 11000111 (planetary), 11101111 (Boulder).
The background x-ray flux is at the class A3 level.
At midnight the visible solar disk was spotless.
Update posted at 13:25 UTC: A solar wind shock was observed at SOHO at 12:17 UTC. This is the arrival of the CME observed on April 8. Initial observations indicate unsettled to active conditions for the remainder of the day.
April 9-10: No obvious Earth directed CMEs were observed in LASCO or
April 8: LASCO observed a faint full halo CME following a long duration B3.7 event in region 11061 peaking at 03:25 UTC.
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
No obvious coronal holes are currently in or near Earth facing locations.
Processed SOHO/EIT 195 image at 23:48 UTC on April 10. 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 to fair. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet initially on April 11. Late in the day and on April 12-13 unsettled and active intervals are possible due to the passage of the CME observed on April 8. Quiet conditions are likely on April 14.
|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
|11061||2010.04.05||1||N13W83||0010||AXX||rotated out of view|
|Total spot count:||1||0|
|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||77.1 (1)||9.1 (2)||(19.4 predicted, +2.3)||(18.11)|
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.