Last update issued on May 15, 2003 at 04:15 UTC.
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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)]
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[Archived reports (last update May 12, 2003)]
The geomagnetic field was unsettled to minor storm on May 14. Solar wind speed ranged between 630 and 776 km/sec under the influence of a high speed stream from coronal hole CH38.
Solar flux measured at 20h UTC on 2.8 GHz was 96.3. The planetary A
index was 27 (STAR Ap - based on the mean of three hour interval ap indices: 28.1).
Three hour interval K indices: 55543443 (planetary), 55543343 (Boulder).
The background x-ray flux is at the class B1 level.
At midnight there were 6 spotted regions on the visible disk. Solar flare activity was very low.
Region 10356 decayed slowly and quietly.
Region 10357 decayed further with the leading spot nearly losing all of its penumbra.
Region 10358 decayed losing penumbra on the trailing spots.
New region 10360 emerged in the southwest quadrant.
Spotted regions not numbered by SEC/NOAA:
[S158] A new region emerged in the southwest quadrant just north of where spotless region 10359 is located. Location at midnight: S13W46. In magnetograms the presence of two separate bipolar regions is evident.
[S159] A new region emerged in the northeast quadrant. Location at midnight: N08E53.
May 12-14: 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 huge recurrent coronal hole (CH38) in the southern hemisphere was in a geoeffective position on May 2-10. A recurrent trans equatorial coronal hole (CH39) will rotate into a geoeffective position on May 15.
Processed SOHO EIT 284 image at 01:06 UTC on May 15. Any black areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to active May 15-16 and quiet to unsettled on May 17. A high speed streams from coronal hole CH39 will likely reach Earth on May 18 and cause unsettled to active geomagnetic conditions that day and on May 19. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is very poor and will likely be very poor until at least May 17. Propagation along north-south paths is fair to good and is likely to be at least fair until May 16. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay. Otherwise more Argentinean stations were audible compared to the previous night, i.e. Radio San Nicolas on 1430 kHz.]
|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|
spots belong to
classification was HSX
at midnight, area 0010
|Total spot count:||25||30|
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||115.1 (1)||43.8 (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 25-45% 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.