Last major update issued on April 14, 2006 at 04:35 UTC.
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The geomagnetic field was quiet to active on April 13. Solar wind speed ranged between 350 and 549 (all day average 436) km/sec. The disturbance associated with the high speed stream from CH220 arrived near noon.
Solar flux measured at 20h UTC on 2.8 GHz was 80.0. The planetary A index was
13 (STAR Ap - based on the mean of three hour interval ap
indices: 13.1).
Three hour interval K indices: 22324423 (planetary), 12334422 (Boulder).
The background x-ray flux is at the class A4 level.
At midnight there were 5 spotted regions on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day.
Region 10869 decayed slowly and will rotate over the southwest limb
today.
Region 10870 decayed further and could become spoptless today.
Region 10871 was quiet and stable.
Region 10872 was quiet and unchanged.
Region 10873 decayed and lost all trailing spots.
April 11-13: No partly or fully Earth directed CMEs were observed in LASCO imagery.
Coronal hole history (since late October 2002)
Compare today's report with the situation one solar rotation ago:
28 days ago
27 days ago
26 days ago
A recurrent trans equatorial coronal hole (CH220) was in an Earth facing position on April 11-14. The southwestern extension of CH220 disappeared on April 13 due to coronal expansion caused by regions 10870 and 10871.
Processed SOHO/EIT 284 image at 01:06 UTC on April 14. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to minor storm on April 14-16 under the influence of a high speed stream from CH220.
| 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.
Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is very poor. Propagation on long distance northeast-southwest paths is fair to good. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay. On other frequencies most the audible stations were from Uruguay (610 Rural, 650 SODRE and so on) and Brazil (750 Jovem Pan and an UNID, 930 Metropolitana to mention a few).
Compare to the previous day's image.
Data for all numbered solar regions according to the Solar Region Summary provided by NOAA/SEC. 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 SEC or where SEC has observed no spots. SEC active region numbers in the table below and in the active region map above are the historic SEC/USAF numbers.
| Active region | Date numbered | SEC spot count |
STAR spot count |
Location at midnight | Area | Classification | Comment |
|---|---|---|---|---|---|---|---|
| 10869 | 2006.04.06 | 1 | 2 | S09W76 | 0040 | HAX | classification was HRX at midnight, area 0020 |
| 10870 | 2006.04.10 | 2 | 2 | S08W19 | 0010 | AXX | |
| 10871 | 2006.04.10 | 6 | 4 | S07E08 | 0030 | CAO | area was 0060 at midnight |
| 10872 | 2006.04.11 | 1 | 2 | S07E46 | 0030 | HSX | |
| 10873 | 2006.04.11 | 9 | 2 | S04E22 | 0050 | DSC | classification was HSX at midnight, area 0040 |
| S645 | 2006.04.10 | N05W31 | plage | ||||
| Total spot count: | 19 | 12 | |||||
| SSN: | 69 | 62 | |||||
| Month | Average solar flux at Earth |
International sunspot number | Smoothed sunspot number |
|---|---|---|---|
| 2000.04 | 184.2 | 125.5 | 120.8 cycle 23 sunspot max. |
| 2000.07 | 202.3 | 170.1 | 119.8 |
| 2001.12 | 235.1 | 132.2 | 114.6 (-0.9) |
| 2005.01 | 102.2 | 31.3 | 34.6 (-0.6) |
| 2005.02 | 97.2 | 29.2 | 33.9 (-0.7) |
| 2005.03 | 89.9 | 24.5 | 33.5 (-0.4) |
| 2005.04 | 86.0 | 24.2 | 31.6 (-1.9) |
| 2005.05 | 99.3 | 42.7 | 28.9 (-2.7) |
| 2005.06 | 93.7 | 39.3 | 28.8 (-0.1) |
| 2005.07 | 96.4 | 40.1 | 29.1 (+0.3) |
| 2005.08 | 90.5 | 36.4 | 27.4 (-1.7) |
| 2005.09 | 91.1 | 21.9 | 25.8 (-1.6) |
| 2005.10 | 77.0 | 8.5 | (24.8 predicted, -1.0) |
| 2005.11 | 86.3 | 18.0 | (22.7 predicted, -2.1) |
| 2005.12 | 90.7 | 41.2 | (19.8 predicted, -2.9) |
| 2006.01 | 83.4 | 15.4 | (16.7 predicted, -3.1) |
| 2006.02 | 76.5 | 4.7 | (13.6 predicted, -3.1) |
| 2006.03 | 75.4 | 10.8 | (11.4 predicted, -2.2) |
| 2006.04 | 91.6 (1) | 30.0 (2) | (10.7 predicted, -0.7) |
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/SEC)
sunspot number. The official international sunspot number is typically
30-50% lower.
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.
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