Last update issued on May 25, 2003 at 03:50 UTC.
[Solar and geomagnetic data - last 4 weeks (updated daily)]
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[Solar cycles 21-23 (last update May 1, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update May 1, 2003)]
[Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update May 1, 2003)]
[Historical solar and geomagnetic data charts 1954-2003 (last update April 13, 2003)]
[Archived reports (last update May 19, 2003)]
The geomagnetic field was unsettled to minor storm on May 24. Solar wind speed ranged between 431 and 581 km/sec under the influence of a high speed stream from coronal hole CH40.
Solar flux measured at 20h UTC on 2.8 GHz was 116.8. The planetary A
index was 23 (STAR Ap - based on the mean of three hour interval ap indices: 22.6).
Three hour interval K indices: 35534344 (planetary), 35423433 (Boulder).
The background x-ray flux is at the class B3 level.
At midnight there were 3 spotted regions on the visible disk. Solar flare activity was very low.
Region 10367 was quiet and stable.
Region 10368 was quiet and stable.
Spotted regions not numbered by SEC/NOAA:
[S169] A new region emerged very quickly after noon on May 24 in the southeast quadrant about 11 degrees longitude east of spotless region 10365. Most of the positive spots are in the south while the negative spots are in the northern part of the region. Further development will make minor M class flaring a possibility. Location at midnight: S08E22.
May 22-24: No obviously 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 recurrent trans equatorial coronal hole (CH40) was in a geoeffective position on May 18-21. A recurrent coronal hole (CH41) in the southern hemisphere was in a geoeffective position on May 24.
Processed SOHO EIT 284 image at 01:06 UTC on May 25. Any black areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to minor storm on May 25 and quiet to unsettled on May 26. On May 27 a high speed stream from coronal hole CH41 will likely arrive and cause unsettled to minor storm conditions that day and on May 28.
Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is very poor and will likely stay very poor until at least May 29. Propagation along north-south paths is poor. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay.]
|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 SEC/NOAA. 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 HAX
|Total spot count:||14||19|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2002.11||168.7||95.5||(84.9 predicted, -5.6)|
|2002.12||157.2||80.8||(80.5 predicted, -4.4)|
|2003.01||144.0||79.5||(77.5 predicted, -3.0)|
|2003.02||124.5||46.2||(72.4 predicted, -5.1)|
|2003.03||131.4||61.5||(66.8 predicted, -5.6)|
|2003.04||126.4||60.0||(61.9 predicted, -4.9)|
|2003.05||113.7 (1)||71.7 (2)||(57.9 predicted, -4.0)|
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 (SEC/NOAA) 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 interpretations, and partly on data from sources noted in solar links. All time references are to the UTC day. Comments and suggestions are always welcome.