Last update issued on September 24, 2003 at 03:40 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 active on September 23. Solar wind speed ranged between 467 and 549 km/sec under the influence of a high speed stream from coronal hole CH59. The geomagnetic disturbance intensified early on September 24 in response to an intensification of the coronal hole stream (higher wind speed and stronger southward swings of the interplanetary magnetic field).
Solar flux measured at 20h UTC on 2.8 GHz was 124.9. The planetary A
index was 17 (STAR Ap - based on the mean of three hour interval ap indices: 17.1).
Three hour interval K indices: 34333343 (planetary), 24323233 (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 single C class event was recorded during the day.
Region 10463 was quiet and stable.
Region 10464 developed slowly with several intermediate spots emerging, all polarity intermixing is occurring in the intermediate spot section. Flare: C2.1 at 14:44 UTC.
Region 10465 developed slowly. In magnetograms this region is very difficult to separate from region 10464. Perhaps the decision to split the regions was premature?
Region 10466 developed slowly and quietly.
New region 10467 emerged in the southeast quadrant early in the day.
Spotted regions not numbered by NOAA/SEC:
[S261] A new region emerged in the southeast quadrant on September 23. Location at midnight: S08E19.
September 21-23: 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
An elongated coronal hole (CH59) in the southern hemisphere was in a geoeffective position on September 18-21. A coronal hole (CH60) in the northern hemisphere will likely rotate into a geoeffective position on September 26-28.
Processed SOHO/EIT 184 image at 19:06 UTC on September 23. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be unsettled to minor storm on September 24 and quiet to active on September 25 due to a high speed stream from coronal hole CH59. Quiet to unsettled is likely on September 26-28.
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 Vibración (Venezuela). The sunrise opening on September 23 was somewhat interesting with 1430 WNEL NotiUno as one of the better catches].
|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|
|10459||2003.09.14||2||S11W84||0030||BXO||rotated out of view|
classification was DSO
classification was DSO
at midnight, area 0040
formerly region S260
|Total spot count:||53||71|
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||105.8 (1)||52.9 (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.