Last update December 20, 2002 at 04:00 UTC.
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The geomagnetic field was quiet to minor storm on December 19. Solar wind speed ranged between 337 and 558 km/sec under the influence of a coronal stream. This coronal stream is not nearly as strong as it was during the previous two solar rotations.
Solar flare activity was moderate. Solar flux was 192.9, the planetary A
index was 21 (STAR Ap - based on the mean of three hour ap indices: 22.0).
Three hour interval K indices: 33454442 (planetary), 33343433 (Boulder).
The background x-ray flux is at the class B8 level.
At midnight there were 9 spotted regions on the visible disk. A total of 17 C and 1 M class flares were recorded during the day.
Region 10218 decayed and was spotless by noon.
Region 10220 rotated out of view at the southwest limb.
Region 10223 remained mostly unchanged and quiet. Flare: C2.1 at 06:52 UTC.
Region 10224 decayed quickly in the leading spot section while slow development was observed in the trailing section.
Region 10225 decayed further and lost all trailing spots.
Region 10226 decayed slowly and has a weak magnetic delta structure in a centrally located penumbra. M class flares are possible. Flares: C2.7 at 00:35, C1.6 at 01:51, C1.7 at 03:08, C2.5 at 05:25, C2.9 at 07:32, C2.3 at 08:21, C2.3 at 09:42, C2.2 at 13:10 and C2.3 at 20:08 UTC.
Region 10227 could soon become spotless if the current rate of decay persists.
Region 10228 reemerged with a few spots. Flare: C1.4 at 11:18 UTC.
Region 10229 decayed slowly and the large trailing penumbra split into two penumbrae. Another M class flare is possible. Flare: M2.7/2N long duration event peaking at 21:53 UTC. This event was a small proton flare as well.
Region 10230 continued to develop at a moderate pace. Mixed polarities are currently observed. A minor M class flare is possible. Flares: C1.3 at 04:41 and C2.9 at 23:55 UTC.
New region 10231 emerged in the southeast quadrant.
December 17-18: No obviously geoeffective CMEs noted.
December 19: A full halo CME was observed after an M2.7 event in region 10229. The CME was first observed in LASCO C2 images at 22:06 UTC off of the northwest limb and will likely reach Earth sometime between late on December 21 and early afternoon on December 22 and could cause active to major storm conditions.
Coronal hole history (starting late October 2002)
Compare today's report with the situation one solar rotation ago: 29 days ago 27 days ago 26 days ago
A well placed coronal hole in the southern hemisphere is rotating into view at the southeast limb and will likely reach a geoeffective position at the central meridian on December 24-25.
Processed SOHO EIT 284 image at 19:06 UTC on December 19. Any black areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to active on December 20-21 due to a coronal stream. Late on December 21 or on Dec.22 a CME will likely impact Earth and cause active to major geomagnetic storming. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is very poor.
|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.
Composite image based on a SOHO/MDI continuum image and overlaid by a coronal hole image. Region numbering has been included. Compare to the previous day 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|
|10220||2002.12.09||1||S13W91||0000||AXX||rotated out of view|
classification was FSO
classification was HAX
classification was HSX
area was 0320 at
|Total spot count:||115||118|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2002.06||148.7||88.3||(106.4 predicted, -2.4)|
|2002.07||173.5||99.9||(102.8 predicted, -3.6)|
|2002.08||183.6||116.4||(99.6 predicted, -3.2)|
|2002.09||175.8||109.3||(96.6 predicted, -3.0)|
|2002.10||167.0||97.5||(93.1 predicted, -3.5)|
|2002.11||168.7||95.0||(87.8 predicted, -5.3)|
|2002.12||167.2 (1)||103.9 (2)||(83.5 predicted, -4.3)|
1) Running average based on the daily 20:00 UT observed solar flux value at 2800
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. Comments and suggestions are always welcome.
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