Last update issued on May 6, 2003 at 03:35 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 5, 2003)]
The geomagnetic field was quiet to active on May 5. Solar wind speed ranged between 413 and 679 km/sec, increasingly under the influence of a high speed stream from coronal hole CH38.
Solar flux measured at 20h UTC on 2.8 GHz was 128.8. The planetary A
index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 13.1).
Three hour interval K indices: 22122444 (planetary), 22222433 (Boulder).
The background x-ray flux is at the class B4 level.
At midnight there were 7 spotted regions on the visible disk. Solar flare activity was low. A total of 4 C class events was recorded during the day.
Region 10345 decayed quickly and quietly. The region lost the northernmost penumbra and most of the penumbral area of the
southern spot. If this rate of decay continues the region will become spotless before rotating over the southwest limb.
Region 10346 was quiet and stable.
Region 10348 developed moderately quickly and could soon become the largest region on the visible disk. There is still a magnetic delta structure in a central penumbra and the region could produce M class flares.
Region 10349 decayed quickly in all sections. There is still a possibility of a minor M class flare. Flares: C2.0 at 06:28, C1.3 at 16:58 and C1.6 at 20:10 UTC.
Region 10351 was quiet and stable.
Region 10354 was quiet and stable.
New region 10355 emerged on May 4 and was numbered the next day.
May 3-5: 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 large recurrent coronal hole (CH38) in the southern hemisphere will rotate into a geoeffective position on May 2-5 and May 7-8.
Processed SOHO EIT 284 image at 19:06 UTC on May 5. Any black areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be unsettled to minor storm until May 11 due to a high speed stream from coronal hole CH38. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is very poor and will likely remain that way until at least May 12. Propagation along north-south paths is fair to good and is likely to be at least fair until May 12. [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 HSX
at midnight, area 0030
classification was FKI
classification was EKC
at midnight, area 0470
area was 0040
|10355||2003.05.05||1||1||N12E45||0020||HSX||formerly region S154|
|Total spot count:||74||63|
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||142.0 (1)||26.0 (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.