Last update issued on September 19, 2003 at 04:05 UTC. No images for September 18.
[Solar and geomagnetic data - last month (updated daily)]
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[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 active to major storm on September 18. Solar wind speed ranged between 753 and 965 km/sec under the influence of a strong high speed stream from coronal hole CH57.
Solar flux measured at 20h UTC on 2.8 GHz was 109.2. The planetary A
index was 40 (STAR Ap - based on the mean of three hour interval ap indices: 40.4).
Three hour interval K indices: 46564445 (planetary), 45454444 (Boulder).
The background x-ray flux is at the class B3-B4 level.
At midnight there were 5 spotted regions on the visible disk. Solar flare activity was low. A total of 2 C class events was recorded during the day. A long duration C1.0 event peaking at 08:01 appears to have had an origin behind the southwest limb. A C2.9 flare at 21:51 was optically uncorrelated.
Region 10459 developed slowly and quietly.
Region 10460 decayed slowly in the trailing spot section while slow development was observed in the leader spots.
Region 10461 was mostly unchanged and quiet.
Region 10462 lost the trailing spot, however, new spots emerged near the leader spot..
Region 10463 was quiet and stable.
September 16-18: 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 large recurrent trans equatorial coronal hole (CH57) was in a geoeffective position on September 14-17. An elongated coronal hole (CH59) in the southern hemisphere could rotate into a geoeffective position on September 18-20.
Processed SOHO/EIT 284 image from 01:06 UTC on September 18. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be unsettled to minor storm until September 20 due to a high speed stream from coronal hole CH57. A high speed stream from coronal hole CH59 will likely cause unsettled to active conditions on September 21-23.
Long distance low frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is useless. Propagation along north-south paths is very poor. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay with an unusually weak 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 |
|---|---|---|---|---|---|---|---|
| 10459 | 2003.09.14 | 13 | 16 | S11W14 | 0070 | DAO |
area was 0130 at midnight |
| 10460 | 2003.09.15 | 3 | 5 | N17E38 | 0040 | CAO | |
| 10461 | 2003.09.16 | 19 | 18 | N13W64 | 0250 | DAO | |
| 10462 | 2003.09.16 | 6 | 7 | S10W59 | 0030 | CSO | |
| 10463 | 2003.09.17 | 1 | 1 | N09E59 | 0080 | HSX | |
| Total spot count: | 42 | 47 | |||||
| SSN: | 92 | 97 | |||||
| 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) |
| 2002.07 | 173.5 | 99.6 | 102.7 (-3.5) |
| 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 | 102.5 (1) | 38.6 (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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