Last update issued on April 7, 2003 at 03:10 UTC.
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The geomagnetic field was quiet to unsettled on April 6. Solar wind speed ranged between 369 and 550 km/sec, slowly decreasing all day.
Solar flux measured at 20h UTC on 2.8 GHz was 125.9. The planetary A
index was 9 (STAR Ap - based on the mean of three hour interval ap indices: 10.1).
Three hour interval K indices: 33222331 (planetary), 23232212 (Boulder).
The background x-ray flux is at the class B3 level.
At midnight there were 6 spotted regions on the visible disk. Solar flare activity was low. A total of 2 C class events was recorded during the day.
Region 10325 decayed slowly with the large umbra splitting into 3 separate umbrae.
Region 10326 was unchanged and quiet.
Region 10330 developed slowly and quietly.
Region 10331 decayed and is losing its leader spot.
Spotted regions not yet numbered by SEC/NOAA:
[S129] A new region emerged northwest of region 10324 in the southeast quadrant on March 30. This region developed until April 4 and decayed quickly on April 5 and 6. Location at midnight: S13W75. Please note that SEC/NOAA has this as region 10324! Flares: C4.2 at 08:11 and C5.9 at 19:28 UTC.
[S132] A new region rotated into view at the northeast limb. Location at midnight: N10E74.
April 5-6: No obviously geoeffective CMEs observed.
April 4: A complex partial halo CME was associated with an M2 long duration event in region S129. This CME could reach Earth on April 7 and cause unsettled to minor geomagnetic storm conditions.
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 small coronal hole (CH30) in the southern hemisphere was in a geoeffective position on April 5. Another and large coronal hole (CH31) in the southern hemisphere will be in a geoeffective position on April 6-9. CH31 is the western part of a huge recurrent coronal hole, the eastern part is rotating into view. The northeastern part of CH31 is trans equatorial.
Processed SOHO EIT 284 image at 19:06 UTC on April 6. Any black areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to unsettled on April 7 with a possibility for unsettled to active conditions late in the day if the CME observed on April 4 reaches Earth. Quiet to active is likely on April 8 as a high speed stream from CH30 reaches Earth, with unsettled to major storm conditions possible on April 9-13 when the high speed stream from CH31 dominates the solar wind. 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 to good. [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|
SECs spots are those
of region S129
classification was HAX
at midnight, area 0220
classification was CSO
at midnight, area 0020
see comment for
|Total spot count:||25||18|
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||147.0 (1)||27.4 (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.