Solar Terrestrial Activity ReportSolar Terrestrial Activity Report

Last update December 25, 2002 at 04:30 UTC.
[Solar and geomagnetic data - last 4 weeks (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update December 2, 2002)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update December 2, 2002)]
[Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update December 2, 
2002)]
[Historical solar and geomagnetic data charts 1954-2002 (last update October 13, 
2002)]
[Archived reports (last update December 23, 2002)]
Recent activity
The geomagnetic field was quiet to active on December 24. Solar wind speed 
ranged between 468 and 574 km/sec. A weak solar wind shock was observed at ACE 
at 13:18 UTC. Solar wind speed increased abruptly from 470 to 520 km/sec and the 
interplanetary magnetic field was at times moderately southwards after the 
shock.
Solar flare activity was low. Solar flux was 147.3, the planetary A index was 18 
(STAR Ap - based on the mean of three hour ap indices: 18.6).
Three hour interval K indices: 32334433 (planetary), 32334433 (Boulder).
The background x-ray flux is at the class B7 level.
At midnight there were 6 spotted regions on the visible disk, 1 of which has not 
yet been numbered. A total of 8 C class events were recorded during the day. 
C2.7 flares at 18:21 and 23:36 were optically uncorrelated.
Region 10223 decayed and became spotless in the early morning.
Region 10224 decayed fairly quickly as the region rotated to the southwest limb. 
Flares: C5.8 at 05:27, C1.6 at 13:29 and C5.8 at 14:51 UTC.
Region 10229 decayed further and had only a single spot left by the end of the 
day.
Region 10230 decayed quickly in the trailing spot section where only two tiny 
spots could be observed at the end of the day.
Region 10231 decayed in the leading spot section while the main trailing  spot 
increased its area.
Region 10233 decayed and was spotless by early afternoon.
New region 10234 rotated into view at the northeast limb early in the day.
Spotted regions not yet numbered by SEC:
[S60] A new region began to emerge in the northeast quadrant late on December 
24. Location at midnight: N11E40.
Coronal mass ejections (CMEs)
December 22: A CME was observed off of the northwest limb early in the day after 
an M1.1 flare and an associated filament eruption in region 10223. The CME does 
not appear to be geoeffective.
December 23-24: No obviously geoeffective CMEs observed.
Coronal holes
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 and well defined trans equatorial coronal hole will be in a geoeffective 
position on December 24-25.

Processed SOHO EIT 284 image at 19:06 UTC on December 24. Any black areas on the 
solar disk are likely coronal holes.
Forecast
The geomagnetic field is expected to be quiet to unsettled on December 25-26. A 
coronal stream will likely arrive early on Dec.27 and cause unsettled to minor 
storm conditions. Long distance medium wave (AM) band propagation along 
east-west paths over high and upper middle latitudes is poor to 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.
Active solar regions (Recent map)

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 regionDate numberedSEC
      spot
      countSTAR
      spot
      countLocation at midnightAreaClassificationComment
      102232002.12.121 N24W830020AXXnow spotless 
      102242002.12.12105S14W810230DAO  
      102252002.12.13  N17W85  plage 
      102262002.12.134 S28W890110EAOrotated out of view 
      102282002.12.14  S14W65  plage 
      102292002.12.1441N25W630050DSOclassification was HSX
      at midnight, area 0030 
      102302002.12.1794S08W340170DSO  
      102312002.12.1953S25W530050DAOclassification was CAO
      at midnight 
      102322002.12.21  N13W47  plage 
      102332002.12.235N13E270030CROnow spotless 
      102342002.12.2411N18E730040HSX  
      S60emerged on
      2002.12.241N11E400000AXX  
      Total spot count:3914
      SSN:11974

Monthly solar cycle data
      MonthAverage solar
      flux at EarthInternational sunspot numberSmoothed sunspot number
      2000.04184.2125.5120.8
      cycle 23 sunspot max. 
      2000.07202.3170.1119.8
      2001.11210.6106.5115.5 (+1.5)
      2001.12235.1132.2114.6 (-0.9)
      2002.01226.6114.1113.5 (-1.1)
      2002.02205.0107.4114.7 (+1.2)
      2002.03179.598.4113.4 (-1.3)
      2002.04189.8120.7110.5 (-2.9)
      2002.05178.4120.8108.8 (-1.7)
      2002.06148.788.3(106.4 predicted, -2.4)
      2002.07173.599.9(102.8 predicted, -3.6)
      2002.08183.6116.4(99.6 predicted, -3.2)
      2002.09175.8109.3(96.6 predicted, -3.0)
      2002.10167.097.5(93.1 predicted, -3.5)
      2002.11168.795.0(87.8 predicted, -5.3)
      2002.12168.1 (1)131.3 (2)(83.5 predicted, -4.3)

1) Running average based on the daily 20:00 UT 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. Comments and suggestions are always welcome.


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