Last update issued on September 21, 2003 at 03:30 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 quiet to minor storm on September 20. Solar wind speed ranged between 580 and 865 km/sec under the influence of a high speed stream from coronal hole CH57.
Solar flux measured at 20h UTC on 2.8 GHz was 111.9. The planetary A
index was 25 (STAR Ap - based on the mean of three hour interval ap indices: 25.4).
Three hour interval K indices: 44544432 (planetary), 56544432 (Boulder).
The background x-ray flux is at the class B6 level.
At midnight there were 4 spotted regions on the visible disk. Solar flare activity was low. A total of 8 C class events was recorded during the day. A C1.1 flare at 04:48 appears to have had a source being the southwest limb. A C2.0 flare at 21:36 and a C2.3 flare at 23:10 both probably had an origin in region 10464.
Region 10459 lost the trailing penumbra, however, several new, small spots emerged.
Region 10460 decayed slowly and quietly.
Region 10463 was quiet and stable.
New region 10464 rotated into view at the northeast limb. This is a moderately large region capable of producing M class flares. There is a magnetic delta structure in the large trailing penumbra and possibly even in the leading penumbra. Flares: C3.0 at 05:12, C1.7 at 06:45, C1.3 long duration event peaking at 11:45, C1.3 at 14:40, C3.6 at 15:36 UTC.
September 18-20: No potentially geoeffective CMEs observed. On September 20 a large full halo CME was observed. Its source was an eruption behind the southwest limb starting at about 09h UTC.
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
An elongated coronal hole (CH59) in the southern hemisphere will be in a geoeffective position on September 18-20.
Processed SOHO/EIT 184 image at 01:06 UTC on September 21. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be unsettled to active until September 23 due to a high speed stream from coronal hole CH59.
Long distance low frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor to very poor. Propagation along north-south paths is poor to fair. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant stations tonight: Radio Vibración (Venezuela). Several stations from Brazil were heard on other frequencies including 1450, 1510 and 1520 kHz].
|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
|Location at midnight||Area||Classification||Comment|
classification was CSO
at midnight, area 0070
|10461||2003.09.16||N13W89||rotated out of view|
|10462||2003.09.16||1||S10W90||0050||HSX||rotated out of view|
classification was HAX
at midnight, area 0100
formerly region S258
area was 0450
|Total spot count:||22||27|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|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||103.4 (1)||43.3 (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.