Last major update issued on May 15, 2006 at 04:00 UTC.
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The geomagnetic field was quiet to active on May 14. Solar wind speed ranged between 450 and 574 (all day average 490) km/sec under the decreasing influence of a high speed stream from CH223.
Solar flux measured at 20h UTC on 2.8 GHz was 72.0. The planetary A index
was 8 (STAR Ap - based on the mean of three hour interval ap
indices: 8.1).
Three hour interval K indices: 34211112 (planetary), 33222222 (Boulder).
The background x-ray flux is at the class A1 level.
At midnight the visible solar disk was spotless. The solar flare activity level was very low. No C class events were recorded during the day.
May 12-14: 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 trans equatorial coronal hole (CH224) was in an Earth facing position on May 12-15. A coronal hole (CH225) in the southern hemisphere will be in an Earth facing position on May 15-17.
Processed SOHO/EIT 284 image at 01:06 UTC on May 15. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to minor storm on May 15-20 due to high speed streams from CH224 and CH225. Isolated major storm intervals are possible.
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 poor to fair. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Tonight Radio Vibración was audible before LSR, then Radio Cristal del Uruguay began to dominate. 1510 kHz had 2 Spanish language stations. The dominant signal was that of Radio Belgrano (Argentina) while the other one probably was Radio San Carlos (Uruguay).
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 |
---|---|---|---|---|---|---|---|
10880 | 2006.05.04 | 1 | S09W71 | 0030 | AXX | spotless | |
10881 | 2006.05.05 | S08W48 | plage | ||||
10883 | 2006.05.07 | S02W40 | plage | ||||
Total spot count: | 1 | 0 | |||||
SSN: | 11 | 0 |
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) |
2005.02 | 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 | 25.5 (-0.3) |
2005.11 | 86.3 | 18.0 | (24.5 predicted, -1.0) |
2005.12 | 90.7 | 41.2 | (21.8 predicted, -2.7) |
2006.01 | 83.4 | 15.4 | (18.7 predicted, -3.1) |
2006.02 | 76.5 | 4.7 | (15.6 predicted, -3.1) |
2006.03 | 75.4 | 10.8 | (13.4 predicted, -2.2) |
2006.04 | 89.0 | 30.2 | (12.7 predicted, -0.7) |
2006.05 | 83.3 (1) | 20.9 (2) | (12.2 predicted, -0.5) |
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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