Last update issued on October 5, 2003 at 04:20 UTC.
[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update October 4, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update October 4, 2003)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update October 4, 2003)]
[Historical solar and geomagnetic data charts 1954-2003 (last update July 23, 2003)]
[Archived reports (last update September 29, 2003)]
The geomagnetic field was quiet to slightly active on October 4. Solar wind speed ranged between 388 and 538 km/sec.
Solar flux measured at 20h UTC on 2.8 GHz was 119.0. The planetary A
index was 9 (STAR Ap - based on the mean of three hour interval ap indices: 9.9).
Three hour interval K indices: 12423222 (planetary), 22413101 (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 moderate. A total of 6 C and 1 M class events was recorded during the day. Optically uncorrelated flares: C1.7 at 05:01 and C1.7 at 19:17 UTC.
Region 10471 developed slightly and still has a magnetic delta structure in a central penumbra. A minor M class flare
is possible. Flares: C2.5 at 13:17, C1.7 at 15:23, impulsive M1.0 at 15:47, C1.6 at 17:57 and
C1.3 at 18:26 UTC.
Region 10472 decayed slowly and quietly.
Region 10473 was quiet and stable.
New region 10474 emerged in the southwest quadrant on October 3 (wrongly labelled as region 10470 then), became spotless early in the day, then redeveloped a few small spots.
Spotted regions not numbered by NOAA/SEC:
[S270] A new region emerged in the southwest quadrant on October just north of spotless region 10470. Location at midnight: S14W36.
[S271] A new region emerged near the southeast limb with a single tiny spot on October 4. Location at midnight: S23E65.
October 2-4: 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 (CH61) in the northern hemisphere and with a trans equatorial extension was in a geoeffective position on October 4-5.
Processed SOHO/EIT 284 image at 13:06 UTC on October 4. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to unsettled October 5-6. A high speed stream from coronal hole CH61 will likely cause unsettled to active conditions on October 7-8, possibly with a few minor storm intervals.
Long distance low frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor to fair. Propagation along north-south paths is fair to good. [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 HSX
|Total spot count:||49||38|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2003.04||126.4||60.0||(69.6 predicted, -4.5)|
|2003.05||115.7||55.2||(65.3 predicted, -4.3)|
|2003.06||129.3||77.4||(61.5 predicted, -3.8)|
|2003.07||127.7||85.0||(58.0 predicted, -3.5)|
|2003.08||122.1||72.7||(55.0 predicted, -3.0)|
|2003.09||112.2||48.8||(53.0 predicted, -2.0)|
|2003.10||125.2 (1)||12.7 (2)||(50.3 predicted, -2.7)|
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.