Last major update issued on February 18, 2004 at 04:35 UTC.
[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update February 2, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update February 2, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update February
2, 2004)]
[Historical solar and geomagnetic data charts 1954-2003 (last update January 16,
2004)]
[Archived reports (last update February 9, 2004)]
The geomagnetic field was quiet on February 17. Solar wind speed ranged between 382 and 598 km/sec. Wind particle density was very low for the second consecutive day while electron content was very high.
Solar flux measured at 20h UTC on 2.8 GHz was 101.9. The planetary A
index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 6.6).
Three hour interval K indices: 22122112 (planetary), 12111212 (Boulder).
The background x-ray flux is at the class A8 level.
At midnight there were 3 spotted regions on the visible disk. Solar flare activity was very low. No C class events was recorded during the day.
Region 10554 decayed slowly and quietly.
Region 10561 decayed slowly and quietly.
Spotted regions not numbered by NOAA/SEC:
[S357] This region emerged in the northwest quadrant on February 17. The region is unimpressive and could soon become
spotless. Location at midnight: N10W25.
February 15-17: No partly or fully earth directed CMEs 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
There is a small coronal hole (CH81) in the southern hemisphere. CH81 will rotate into a potentially geoeffective position on February 17.
Processed SOHO/EIT 284 image at 01:06 UTC on February 18. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet on February 18-19. On February 20 there is a possibility of a weak high speed stream arriving from coronal hole CH81, this could cause unsettled to active conditions during parts of that day.
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 to good. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay and Radio Vibración (Venezuela). Propagation was best towards the São Paulo and Rio de Janeiro area in Brazil, particularly before 03h UTC, with stations on 940, 1230, 1410 and 1440 all having strong signals].
| 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.
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 |
|---|---|---|---|---|---|---|---|
| 10554 | 2004.02.07 | 1 | 1 | S08W56 | 0050 | HSX | |
| 10555 | 2004.02.09 | S16W35 | plage | ||||
| 10556 | 2004.02.11 | N17W58 (SEC: N15W67) |
plage SEC has moved region 10556 to the position of region S354 |
||||
| 10557 | 2004.02.13 | S11W84 | plage | ||||
| 10558 | 2004.02.13 | S16W19 | plage | ||||
| 10559 | 2004.02.14 | N07W81 | plage | ||||
| 10560 | 2004.02.15 | S17E04 | plage | ||||
| 10561 | 2004.02.15 | 1 | 2 | N02E39 | 0030 | HSX | |
| S354 | emerged on 2004.02.14 |
N16W68 | plage | ||||
| S357 | emerged on 2004.02.17 |
2 | N10W25 | 0000 | AXX | ||
| Total spot count: | 2 | 5 | |||||
| SSN: | 22 | 35 | |||||
| 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) |
| 2003.01 | 144.0 | 79.7 | 80.8 (-1.2) |
| 2003.02 | 124.5 | 46.0 | 78.3 (-2.5) |
| 2003.03 | 131.4 | 61.1 | 74.0 (-4.3) |
| 2003.04 | 126.4 | 60.0 | 70.1 (-3.9) |
| 2003.05 | 115.7 | 55.2 | 67.6 (-2.5) |
| 2003.06 | 129.3 | 77.4 | 65.0 (-2.6) |
| 2003.07 | 127.7 | 83.3 | 61.8 (-3.2) |
| 2003.08 | 122.1 | 72.7 | (59.4 predicted, -2.4) |
| 2003.09 | 112.2 | 48.7 | (57.6 predicted, -1.8) |
| 2003.10 | 151.7 | 65.6 | (54.9 predicted, -2.7) |
| 2003.11 | 140.8 | 67.2 | (52.2 predicted, -2.7) |
| 2003.12 | 114.9 | 47.0 | (49.6 predicted, -2.6) |
| 2004.01 | 114.1 | 37.2 | (45.4 predicted, -4.2) |
| 2004.02 | 106.7 (1) | 46.6 (2) | (40.8 predicted, -4.6) |
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 sources noted in solar links. All time references are to the UTC day. Comments and suggestions are always welcome.
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