Last update issued on September 27, 2003 at 03:10 UTC.
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[Solar cycles 21-23 (last update September 1, 2003)]
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[Graphical comparison of cycles 21, 22 and 23 (last update September 1, 2003)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update September
1, 2003)]
[Historical solar and geomagnetic data charts 1954-2003 (last update July 23, 2003)]
[Archived reports (last update September 16, 2003)]
The geomagnetic field was unsettled to active on September 26. Solar wind speed ranged between 531 and 652 km/sec, gradually decreasing all day as the influence of the high speed stream from coronal hole CH59 lessened.
Solar flux measured at 20h UTC on 2.8 GHz was 131.1. The planetary A
index was 17 (STAR Ap - based on the mean of three hour interval ap indices: 17.9).
Three hour interval K indices: 33443333 (planetary), 43543443 (Boulder).
The background x-ray flux is at the class B3 level.
At midnight there were 6 spotted regions on the visible disk. Solar flare activity was low. A total of 2 C class event was recorded during the day.
Region 10463 decayed slowly and quietly.
Region 10464 decayed slightly in the trailing spot section while slow development continued in the intermediate
spot section. An M class flares are possible. Flares: C1.3 at 14:55 and C2.3 at 17:52 UTC.
Region 10466 developed slowly as new spots emerged to the north of the main penumbra.
Region 10467 developed slowly and quietly.
Spotted regions not numbered by NOAA/SEC:
[S261] A new region emerged in the southeast quadrant on September 23 and was mostly unchanged September 24-26. Location at midnight:
S08W23.
[S262] This region emerged in the southwest quadrant on September 26. Location at midnight: S10W11.
September 24-26: No potentially geoeffective CMEs observed. LASCO images for September 26 only covered a few hours of the day. There will be relatively few new SOHO and LASCO images until approximately October 10.
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 coronal hole (CH60) in the northern hemisphere will rotate into a geoeffective position on September 26-28.
Processed SOHO/EIT 284 image at 19:06 UTC on September 25. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be mostly quiet to unsettled on September 27-28 becoming unsettled to active on September 29 - October 1 due to a high speed stream from coronal hole CH60.
Long distance low frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is very poor. Propagation along north-south paths is poor. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay].
| 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.
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.
| Solar region | Date numbered | SEC spot count |
STAR spot count |
Location at midnight | Area | Classification | Comment |
|---|---|---|---|---|---|---|---|
| 10460 | 2003.09.15 | N17W73 | plage | ||||
| 10463 | 2003.09.17 | 1 | 1 | N08W50 | 0030 | HSX | |
| 10464 | 2003.09.20 | 57 | 70 | N04W07 | 0610 | FKI |
beta-gamma area was 0850 at midnight |
| 10465 | 2003.09.22 | 7 | S01W03 | 0010 | BXO | spotless | |
| 10466 | 2003.09.22 | 5 | 9 | S07E19 | 0060 | CSO | |
| 10467 | 2003.09.23 | 7 | 7 | S10E06 | 0020 | CSO |
classification was DAO at midnight, area 0040 |
| 10468 | 2003.09.23 | N16W55 | plage | ||||
| S261 | emerged on 2003.09.23 |
2 | S08W23 | 0000 | AXX | ||
| S262 | emerged on 2003.09.26 |
6 | S10W11 | 0020 | CRO | ||
| Total spot count: | 77 | 95 | |||||
| SSN: | 127 | 155 | |||||
| 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) |
| 2002.08 | 183.6 | 116.4 | 98.7 (-4.0) |
| 2002.09 | 175.8 | 109.6 | 94.6 (-4.1) |
| 2002.10 | 167.0 | 97.5 | 90.5 (-4.1) |
| 2002.11 | 168.7 | 95.5 | 85.2 (-5.3) |
| 2002.12 | 157.2 | 80.8 | 82.0 (-3.2) |
| 2003.01 | 144.0 | 79.7 | 81.0 (-1.0) |
| 2003.02 | 124.5 | 46.0 | 78.5 (-2.5) |
| 2003.03 | 131.4 | 61.1 | (74.2 predicted, -4.3) |
| 2003.04 | 126.4 | 60.0 | (69.3 predicted, -4.9) |
| 2003.05 | 115.7 | 55.2 | (64.4 predicted, -4.9) |
| 2003.06 | 129.3 | 77.4 | (60.4 predicted, -4.0) |
| 2003.07 | 127.7 | 85.0 | (56.9 predicted, -3.5) |
| 2003.08 | 122.1 | 72.7 | (53.9 predicted, -3.0) |
| 2003.09 | 108.9 (1) | 65.3 (2) | (51.9 predicted, -2.0) |
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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