Last major update issued on April 15, 2005 at 03:25 UTC.
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The geomagnetic field was quiet to minor storm on April 14. Solar wind speed ranged between 472 and 566 km/sec under the slowly decreasing influence of a high speed stream from CH157.
Solar flux measured at 20h UTC on 2.8 GHz was 85.4. The planetary
A
index was 19 (STAR Ap - based on the mean of three hour interval ap
indices: 18.9).
Three hour interval K indices: 45333232 (planetary), 45443332 (Boulder).
The background x-ray flux is at the class A7 level.
At midnight there were 4 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 10750 decayed slowly and quietly.
Region 10752 simplified somewhat as the leading umbra merged into a symmetrical penumbra and trailing spots decayed.
Region 10753 decayed slowly and quietly.
New region 10754 emerged in the southeast quadrant on April 14.
April 12-14: No obvious fully or partly Earth directed CMEs were observed.
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 coronal hole (CH158) in the southern hemisphere will be in an Earth facing position on April 15-16.
Processed SOHO/EIT 284 image at 19:06 UTC on April 14. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to active on April 15 and quiet to unsettled on April 16-17. Effects from CH158 could reach Earth on April 18 and cause unsettled to active conditions.
| 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) Material from a CME is likely to impact 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 along long distance north-south paths is fair. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay while Radio Rafaela (Argentina) and Radio Vibración (Venezuela) were both noted occasionally. Propagation was best towards Brazil, Argentina and Uruguay. Rádio Metropolitana (Brazil) on 930 kHz was noted above the Uruguayan station for several hours. Radio del Plata (Argentina) on 1030 and SODRE (Uruguay) on 1050 kHz had the best signals.
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 |
|---|---|---|---|---|---|---|---|
| 10749 | 2005.04.03 | S06W82 | plage | ||||
| 10750 | 2005.04.05 | 2 | 2 | S07W41 | 0040 | HSX | classification was CSO at midnight, area 0020 |
| 10752 | 2005.04.12 | 10 | 5 | N01E43 | 0160 | EAI | classification was DSO at midnight, area 0100 |
| 10753 | 2005.04.13 | 6 | 2 | N12W19 | 0010 | BXO | classification was CRO at midnight |
| 10754 | 2005.04.14 | 5 | 4 | S08E51 | 0080 | DAI | classification was DSO at midnight, area 0050 |
| S533 | emerged on 2005.04.09 |
N19W67 | plage | ||||
| Total spot count: | 23 | 13 | |||||
| SSN: | 63 | 53 | |||||
| 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) |
| 2004.02 | 107.0 | 45.8 | 49.3 (-2.7) |
| 2004.03 | 112.0 | 49.1 | 47.1 (-2.2) |
| 2004.04 | 101.2 | 39.3 | 45.5 (-1.6) |
| 2004.05 | 99.8 | 41.5 | 43.8 (-1.7) |
| 2004.06 | 97.4 | 43.2 | 41.6 (-2.2) |
| 2004.07 | 119.1 | 51.1 | 40.2 (-1.4) |
| 2004.08 | 109.6 | 40.9 | 39.2 (-1.0) |
| 2004.09 | 103.1 | 27.7 | 37.5 (-1.7) |
| 2004.10 | 105.9 | 48.0 | (35.6 predicted, -1.9) |
| 2004.11 | 113.2 | 43.5 | (33.9 predicted, -1.7) |
| 2004.12 | 94.5 | 17.9 | (31.6 predicted, -2.3) |
| 2005.01 | 102.2 | 31.3 | (28.9 predicted, -2.7) |
| 2005.02 | 97.2 | 29.1 | (26.5 predicted, -2.4) |
| 2005.03 | 89.9 | 24.8 | (24.7 predicted, -1.8) |
| 2005.04 | 85.3 (1) | 20.0 (2) | (22.9 predicted, -1.8) |
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% less.
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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