Last major update issued on April 3, 2010 at 05:30 UTC. Minor update posted at 17:10 UTC.
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The geomagnetic field was quiet to unsettled on April 2. Solar wind speed ranged between 404 and 544 km/s. An unexpected solar wind shock was observed at SOHO at 06:45 UTC.
Solar flux measured at 20h UTC on 2.8 GHz was 76.2. The planetary A index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 12.5). Three hour interval K indices: 32332223 (planetary), 32443322 (Boulder).
The background x-ray flux is at the class A4 level.
At midnight there were 2 spotted regions on the visible solar disk.
Region 11057 decayed slowly and quietly.
Region 11059 decayed and was quiet.
Update added at 17:10 UTC: A long duration B7.4 event peaking at 09:54 UTC on April 3 and centered at region 11059 produced at least a partial halo CME as observed in LASCO C2 images. The CME could reach Earth on April 6 and cause unsettled to active conditions.
March 31 - April 2: 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 recurrent coronal hole (CH398) in the northern hemisphere will be in an Earth facing position on April 3-4.
Processed SOHO/EIT 195 image at 01:13 UTC on April 3. 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 to fair.
The geomagnetic field is expected to be quiet to unsettled on April 3 and quiet on April 4-5. Effects from CH398 could cause quiet to active conditions on April 6-8.
|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||4||3||N16W59||0250||HHX||classification was HAX at midnight, area 0150|
|Total spot count:||8||6|
|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||77.7 (1)||1.8 (2)||(19.4 predicted, +2.3)||(12.19)|
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.