Last update issued on May 1, 2003 at 03:15 UTC.
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[Solar cycles 21-23 (last update April 2, 2003)]
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The geomagnetic field was active to major storm on April 30. Solar wind speed ranged between 490 and 684 km/sec. The interplanetary magnetic field appeared to be under the combined influence of a high speed stream from coronal hole CH37 and the CME based disturbance which dominated the IMF on April 29.
Solar flux measured at 20h UTC on 2.8 GHz was 153.5. The planetary A
index was 40 (STAR Ap - based on the mean of three hour interval ap indices: 40.8).
Three hour interval K indices: 56554445 (planetary), 56543444 (Boulder).
The background x-ray flux is at the class B5 level.
At midnight there were 9 spotted regions on the visible disk. Solar flare activity was low. A total of 2 C class events was recorded during the day. A C1.0 long duration event peaking just after 18h UTC was associated with a filament eruption just west of region 10345. This event may have caused a small CME but I haven't been able to confirm that yet.
Region 10337 decayed quickly and is rotating over the southwest limb.
Region 10344 decayed further. The leading penumbra is about to split into two penumbrae.
Region 10345 was mostly unchanged and quiet.
Region 10346 was quiet and stable.
Region 10348 decayed slowly and lost the leader spots. The region could soon become spotless.
Region 10349 continued to add penumbral area and has become a huge region. The magnetic field layout is still relatively simple for such a large region. The only area showing any degree of complexity is in the central spots section where a weak delta structure could be developing. The region is capable of producing X class flares but will likely need to become more complex for that to happen. Any major flare over the next few days would likely be associated with a large geoeffective CME. Flare: C1.0 at 01:28 UTC.
New region 10350 emerged on April 28 and was numbered by SEC two days later, or rather, the region was initially numbered region 10340 on April 29. Realizing their mistake SEC renumbered the region. The region decayed slowly on April 30.
New region 10351 rotated into view at the northeast limb.
Spotted regions not yet numbered by SEC/NOAA:
[S148] A new region emerged early on April 30 in hot plage in the southeast quadrant. Location at midnight: S24E52.
April 28-30: 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 coronal hole (CH38) in the southern hemisphere will rotate into a geoeffective position on May 3-5.
Processed SOHO EIT 284 image at 19:06 UTC on April 30. Any black areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be unsettled to major storm on May 1 and quiet to active on May 2-3. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is useless and will likely remain useless to very poor until at least May 3. Propagation along north-south paths is good and will likely be fair to good until May 3. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: an unidentified station from Brazil with QRM from at least 2 other stations from the same country. Other frequencies were more interesting. 930 kHz was surprisingly dominated by Rádio Metropolitana, Fortaleza. At times 2 other stations from Brazil were heard as well as the usually dominant Radio Monte Carlo, Montevideo]
|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 0050
classification was DAO
classification was AXX
at midnight, area 0010
classification was EKC
at midnight, area 1100
|10350||2003.04.30||6||8||S12W58||0070||DAO||formerly region S146|
|Total spot count:||80||116|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2002.10||167.0||97.5||(91.0 predicted, -3.6)|
|2002.11||168.7||95.0||(85.7 predicted, -5.3)|
|2002.12||157.2||81.6||(81.3 predicted, -4.4)|
|2003.01||144.0||79.5||(78.3 predicted, -3.0)|
|2003.02||124.5||46.2||(73.3 predicted, -5.0)|
|2003.03||131.4||61.5||(67.6 predicted, -5.7)|
|2003.04||126.4 (1)||114.3 (2)||(62.7 predicted, -4.9)|
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.