Last update issued on September 20, 2003 at 04:10 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 19. Solar wind speed ranged between 595 and 874 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 111.1. The planetary A
index was 32 (STAR Ap - based on the mean of three hour interval ap indices: 33.3).
Three hour interval K indices: 44555443 (planetary), 44544433 (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 events was recorded during the day. A C1.6 flare at 18:20 and a C1.1 event peaking at 23:07 UTC were both optically uncorrelated.
Region 10459 decayed and lost penumbral area, particularly in the trailing spot section.
Region 10460 decayed slowly and could become spotless in 1 or 2 days if the current rate of decay persists.
Region 10461 decayed in the trailing spot section and is rotating over the northwest limb.
Region 10462 was mostly unchanged and is rotating over the southwest limb.
Region 10463 was quiet and stable.
Spotted regions not numbered by NOAA/SEC:
[S258] A new region rotated partially into view at the northeast limb on September 19. The leading penumbra is fairly large and the region may be capable of producing isolated minor M class flares. Location at midnight: N02E82.
September 17-19: 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 will be in a geoeffective position on September 18-20.
Processed SOHO/EIT 195 image at 02:00 UTC on September 20. 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 high speed streams from coronal holes CH57 and CH59.
Long distance low frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is 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) and Cadena Peruana de Noticias].
|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 0040
|Total spot count:||21||31|
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||102.9 (1)||40.9 (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.