Last major update issued on March 22, 2006 at 05:35 UTC.
[Solar and
geomagnetic data - last month (updated daily)]
[Solar wind and
electron fluence charts (updated daily)]
[Solar cycles 21-23
(last update March 2, 2006)]
[Solar cycles 1-20]
[Graphical comparison
of cycles 21, 22 and 23 (last update March 2, 2006)]
[Graphical
comparison of cycles 2, 10, 13, 17, 20 and 23 (last update March 2, 2006)]
[Historical solar and
geomagnetic data charts 1954-2005 (last update March 3, 2006)]
[Archived reports (last update
March 2, 2006)]
The geomagnetic field was quiet to active on March 21. Solar wind speed ranged between 541 and 620 (all day average 576) km/sec under the influence of a high speed stream from CH216.
Solar flux measured at 20h UTC on 2.8 GHz was 76.7. The planetary A index
was 13 (STAR Ap - based on the mean of three hour interval ap
indices: 13.4).
Three hour interval K indices: 34113333 (planetary), 34133333 (Boulder).
The background x-ray flux is at the class A8 level.
At midnight there were 2 spotted regions on the visible solar disk. The solar flare activity level was low. A total of 6 C class events were recorded during the day.
Region 10862 developed early in the day, then began to decay. Flares: C2.5 at 09:44, C1.3 at 12:04, C2.4 at 16:33, C1.2 at 18:42, C1.1 at 19:20 and C2.1 at 23:26 UTC.
Spotted regions not numbered by NOAA/SEC:
[S634] This region emerged on March 20 in the northwest quadrant due
north of region 10862 and has reversed polarities. Location at midnight: N07W40.
March 19-21: 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 (CH216) was in an Earth facing position on March 16-17. A trans equatorial coronal hole (CH217) was in an Earth facing position on March 21-22.
Processed SOHO/EIT 284 image at 19:06 UTC on March 21. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to unsettled on March 22-23. Effects from CH217 could reach Earth on March 24 and cause unsettled to active intervals that day and on March 25.
| 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 poor. Propagation on long distance northeast-southwest paths is fair to poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant stations tonight: Radio Vibración (Venezuela). Propagation was best to Venezuela (550 YVKE Radio Mundial fair signal) and Colombia. A few stations from Newfoundland and Florida were heard with weak 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 |
|---|---|---|---|---|---|---|---|
| 10860 | 2006.03.14 | S04W42 | plage | ||||
| 10861 | 2006.03.15 | S11W32 | plage | ||||
| 10862 | 2006.03.18 | 29 | 21 | S07W39 | 0120 | DAI | beta-gamma area was 0080 at midnight |
| S633 | 2006.03.17 | S12W47 | plage | ||||
| S634 | 2006.03.20 | 2 | N07W40 | 0010 | BXO | reversed polarities | |
| Total spot count: | 29 | 23 | |||||
| SSN: | 39 | 43 | |||||
| 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 | (25.6 predicted, -1.8) |
| 2005.10 | 77.0 | 8.5 | (23.8 predicted, -1.8) |
| 2005.11 | 86.3 | 18.0 | (21.4 predicted, -2.4) |
| 2005.12 | 90.7 | 41.2 | (18.5 predicted, -2.9) |
| 2006.01 | 83.4 | 15.4 | (15.4 predicted, -3.1) |
| 2006.02 | 76.5 | 4.7 | (12.3 predicted, -3.1) |
| 2006.03 | 74.1 (1) | 13.3 (2) | (10.1 predicted, -2.2) |
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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