Last update issued on September 26, 2003 at 04:05 UTC.
[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update September 1, 2003)]
[Solar cycles 1-20]
[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 minor storm on September 25. Solar wind speed ranged between 586 and 787 km/sec under the influence of a high speed stream from coronal hole CH59. Solar wind speed decreased gradually after 15h UTC and the high speed stream appeared to be ending late in the day.
Solar flux measured at 20h UTC on 2.8 GHz was 132.6. The planetary A
index was 28 (STAR Ap - based on the mean of three hour interval ap indices: 28.8).
Three hour interval K indices: 44554443 (planetary), 44554433 (Boulder).
The background x-ray flux is at the class B4 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 slowly in the leading and trailing spot sections while development continued in the intermediate
spot section. There is a magnetic delta structure near the center of the region and minor M class flares are possible. Flares:
C1.1 at 00:35 and C1.1 at 17:25 UTC.
Region 10465 was quiet and stable.
Region 10466 decayed and lost penumbra on the trailing spots.
Region 10467 decayed 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 on September 24 and 25. Location at midnight:
S08W07.
September 23-25: No potentially geoeffective 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
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 26-28 becoming unsettled to active on September 29-30 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 to fair. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay with a rather strong signal].
| 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 | N17W60 | plage | ||||
| 10463 | 2003.09.17 | 2 | 2 | N09W35 | 0050 | CSO |
classification was HAX at midnight |
| 10464 | 2003.09.20 | 50 | 59 | N04E09 | 0580 | FKC |
beta-gamma-delta
area was 0850 at midnight |
| 10465 | 2003.09.22 | 9 | 2 | N00E10 | 0020 | DRO |
classification was HSX at midnight |
| 10466 | 2003.09.22 | 7 | 7 | S05E34 | 0100 | DSO |
classification was CSO at midnight |
| 10467 | 2003.09.23 | 4 | 7 | S10E20 | 0030 | CSO |
classification was DSO at midnight |
| 10468 | 2003.09.23 | N16W42 | plage | ||||
| S261 | emerged on 2003.09.23 |
3 | S08W07 | 0000 | AXX | ||
| Total spot count: | 72 | 80 | |||||
| SSN: | 122 | 140 | |||||
| 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 | 108.0 (1) | 61.0 (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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