Last update issued on May 7, 2003 at 02:30 UTC.
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[Solar cycles 1-20]
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[Archived reports (last update May 5, 2003)]
The geomagnetic field was unsettled to minor storm on May 6. Solar wind speed ranged between 566 and 780 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 122.0. The planetary A
index was 23 (STAR Ap - based on the mean of three hour interval ap indices: 23.4).
Three hour interval K indices: 43345444 (planetary), 33345434 (Boulder).
The background x-ray flux is at the class B7 level.
At midnight there were 7 spotted regions on the visible disk. Solar flare activity was low. A total of 7 C class events was recorded during the day.
Region 10346 was quiet and stable. The region will be rotating over the northwest limb today.
Region 10348 developed in the leader spots, however, moderately quick decay was observed in other parts of the region. A minor M class flare is possible until the region rotates out of view on May 8. Flares: C2.0 at 20:47 and C2.6 at 21:14 UTC.
Region 10349 continued to decay quickly in all sections. A minor M class flare is possible until the region rotates behind the southwest limb on May 8. Flares: C3.2 long duration event peaking at 01:48, C5.7 long duration event peaking at 10:20, C3.7 at 14:10, C1.3 at 17:29 and C2.8 at 19:25 UTC.
Region 10351 was quiet and stable.
Region 10353 reemerged with a single spot.
Region 10354 was quiet and stable.
Region 10355 decayed and could soon become spotless.
May 4-6: 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 will rotate into a geoeffective position on May 2-9.
Processed SOHO EIT 284 image at 14:07 UTC on May 6. 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 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: None, several stations from Brazil were heard with good signal strength - the best night for Brazil since nightly monitoring started in late January. The usually dominant Radio Cristal del Uruguay surfaced briefly only a few times.]
|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|
area was 0450
classification was EKC
at midnight, area 0330
classification was HRX
|Total spot count:||47||44|
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||138.7 (1)||29.8 (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.