Last update issued on May 4, 2003 at 03:30 UTC.
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The geomagnetic field was quiet to unsettled on May 3. Solar wind speed ranged between 445 and 552 km/sec.
Solar flux measured at 20h UTC on 2.8 GHz was 147.7. The planetary A
index was 10 (STAR Ap - based on the mean of three hour interval ap indices: 11.3).
Three hour interval K indices: 23332222 (planetary), 24342212 (Boulder).
The background x-ray flux is at the class B5 level.
At midnight there were 10 spotted regions on the visible disk. Solar flare activity was low. A total of 4 C class events was recorded during the day.
Region 10344 is rotating quietly over the northwest limb. Flares: C1.4 at 09:50
and C1.0 at 12:08 UTC.
Region 10345 decayed slowly and simplified. No polarity intermixing was obvious at the end of the day. Flare: C2.7 at 18:31 UTC.
Region 10346 was quiet and stable.
Region 10348 developed moderately quickly. C class flares are possible. The proximity of region S151 could cause minor M class flares.
Region 10349 decayed further in the trailing spot section. An interesting development is the emergence of positive polarity flux in the central spot section. A magnetic delta structure could be forming in a quickly expanding penumbra in this part of the region. Should this development continue the chance of an M class flare will increase strongly. Flare: C1.0 at 21:36 UTC.
Region 10351 was quiet and stable.
Spotted regions not yet numbered by SEC/NOAA:
[S150] A new region emerged on May 2 in the southwest quadrant. Location at midnight: S01W43.
[S151] A new region emerged on May 3 in the southwest quadrant just west of region 10348. Location at midnight: S34W34. The trailing positive polarity penumbra is quite close to the leading negative polarity penumbra of region 10348.
[S152] A new region emerged on May 3 in the southeast quadrant. Location at midnight: S16E45.
[S153] A new region rotated into view on May 3 at the northeast limb. Location at midnight: N20E71.
May 1-3: 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.
Processed SOHO EIT 284 image at 19:06 UTC on May 3. Any black areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to unsettled on May 4 and the first half of May 5. Then a high speed stream from coronal hole CH38 will begin dominating the solar wind and cause unsettled to minor storm conditions until May 9. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is very poor. Propagation along north-south paths is fair. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay and Cadena Peruana de Noticias.]
|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 DAO
at midnight, area 0060
area was 0950
classification was HSX
|Total spot count:||74||119|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2002.11||168.7||95.0||(84.9 predicted, -5.6)|
|2002.12||157.2||81.6||(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||146.5 (1)||15.8 (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.