Last update issued on September 15, 2003 at 02:55 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 8, 2003)]
The geomagnetic field was quiet to unsettled on September 14. Solar wind speed ranged between 360 and 475 km/sec.
Solar flux measured at 20h UTC on 2.8 GHz was 94.7. The planetary A
index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 8.4).
Three hour interval K indices: 21222322 (planetary), 21223221 (Boulder).
The background x-ray flux is at the class B2 level.
At midnight there were 4 spotted regions on the visible disk. Solar flare activity was low. A total of 4 C class events was recorded during the day.
Region 10456 decayed further in the leading and trailing parts. Some development was observed in the central part
and the region could produce further C class flares while rotating over the southwest limb today and tomorrow. Flares:
C4.4 at 01:25 and C4.0 at 22:43 UTC.
Region 10458 decayed slowly and could become spotless today.
New region 10459 emerged in the southeast quadrant early in the day.
Spotted region not numbered by NOAA/SEC:
[S255] A new region emerged in the northwest quadrant on September 14. Location at midnight: N13W11.
September 13-14: No potentially geoeffective CMEs observed.
September 12: A full halo CME was observed early in the day. The CME was best defined over the south pole and was faint over the northern limbs. The source of this CME is likely the B8 event which occurred late on September 11 when a filament erupted just south of region S253. The CME is likely to reach Earth early on September 15.
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
Small coronal holes (CH56 and CH58) near the equator were in a geoeffective position on September 13 and appeared to close on September 14. A recurrent trans equatorial coronal hole (CH57) will rotate into a geoeffective position on September 14-17. This coronal hole has been developing since September 12, particularly in the section located in the northern hemisphere.
Processed SOHO/EIT 284 image from 01:06 UTC on September 15. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to active on September 15-16. A high speed stream from coronal hole CH57 will likely cause unsettled to minor storm conditions on September 17-20.
Long distance low frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is fair. Propagation along north-south paths is fair. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración (Venezuela) with a strong 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
|Location at midnight||Area||Classification||Comment|
classification was DAI
classification was AXX
at midnight, area 0010
|Total spot count:||28||23|
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||102.4 (1)||27.5 (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.