Last major update issued on March 21, 2005 at 04:30 UTC.
[Solar and
geomagnetic data - last month (updated daily)]
[Solar wind and
electron fluence charts (updated daily)]
[Solar cycles 21-23
(last update March 3, 2005)]
[Solar cycles 1-20]
[Graphical comparison
of cycles 21, 22 and 23 (last update March 3, 2005)]
[Graphical
comparison of cycles 2, 10, 13, 17, 20 and 23 (last update March 3, 2005)]
[Historical solar and
geomagnetic data charts 1954-2004 (last update February 1, 2005)]
[Archived reports
(last update March 16, 2005)]
The geomagnetic field was quiet on March 20. Solar wind speed ranged between 331 and 441 km/sec, steadily decreasing all day.
Solar flux measured at 20h UTC on 2.8 GHz was 89.0. The planetary
A
index was 5 (STAR Ap - based on the mean of three hour interval ap
indices: 5.1).
Three hour interval K indices: 12122111 (planetary), 13122231 (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 3 C class events was recorded during the day. Region 10742 behind the southwest limb produced a C4.1 flare at 01:59 UTC.
Region 10743 decayed losing both spots and penumbral area. Flares: C1.2 at 06:14 and
C2.1 at 11:52 UTC.
New region 10744 emerged in the southeast quadrant on March 19 and was numbered the next day by SEC. The region added some
penumbral area on March 20, however, the separation between the opposite polarity areas increased. Unless new flux emerges the
region is likely to decay.
March 18-20: 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 trans equatorial coronal hole (CH153) will rotate to a geoeffective position on March 21-23, the westernmost part is only in the northern hemisphere and poorly defined.
Processed SOHO/EIT 284 image at 13:06 UTC on March 11. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be mostly quiet on March 21-23 becoming quiet to unsettled on March 24 due to effects from CH153. Quiet to active conditions are likely on March 25-26 as the coronal hole effects increase.
| 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 fair to occasionally good. Propagation along long distance north-south paths is very poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant stations tonight: Radio Vibración (Venezuela) before 03h UTC with a fair signal, then, gradually, WWNN Boca Raton FL and WLAM Lewiston ME took over dominance. Propagation towards North America is improving and several stations had fair to good signals. Surprisingly CJYQ on 930 kHz was poor and allowed Radio Surco (Cuba) to dominate the frequency.
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 |
|---|---|---|---|---|---|---|---|
| 10743 | 2005.03.09 | 12 | 5 | S08W70 | 0310 | DAO | classification was DSO at midnight, area 0200 |
| 10744 | 2005.03.20 | 7 | 13 | S12E01 | 0060 | DSO |
formerly region S526 classification was DAO at midnight, area 0090 |
| S524 | visible on 2005.03.10 |
N16W66 | plage | ||||
| S525 | emerged on 2005.03.14 |
S13W45 | plage | ||||
| Total spot count: | 19 | 18 | |||||
| SSN: | 39 | 38 | |||||
| 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) |
| 2004.01 | 114.1 | 37.3 | 52.0 (-2.8) |
| 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 | 43.9 (-1.6) |
| 2004.06 | 97.4 | 43.2 | 41.7 (-2.2) |
| 2004.07 | 119.1 | 51.0 | 40.3 (-1.4) |
| 2004.08 | 109.6 | 40.9 | 39.2 (-1.1) |
| 2004.09 | 103.1 | 27.7 | (37.4 predicted, -1.8) |
| 2004.10 | 105.9 | 48.4 | (35.2 predicted, -2.2) |
| 2004.11 | 113.2 | 43.7 | (33.3 predicted, -1.9) |
| 2004.12 | 94.5 | 17.9 | (31.0 predicted, -2.3) |
| 2005.01 | 102.2 | 31.3 | (28.3 predicted, -2.7) |
| 2005.02 | 97.2 | 29.1 | (25.9 predicted, -2.4) |
| 2005.03 | 94.2 (1) | 27.5 (2) | (24.1 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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