Solar Terrestrial Activity ReportSolar Terrestrial Activity Report

Last update September 9, 2002 at 03:00 UTC.
[Solar and geomagnetic data - last 4 weeks (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update September 3, 2002)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update September 3, 2002)]
[Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update September 3, 
2002)]
[Historical solar and geomagnetic data charts 1954-2002 (last update August 16, 
2002)]
Recent development
The geomagnetic field was quiet to major storm on September 8. Solar wind speed 
ranged between 438 and 550 km/sec.
Solar flare activity was moderate. Solar flux was 191.6, the planetary A index 
was 26 (3-hour planetary K indices: 6532 2244, Boulder K indices: 6522 3223). 
Region 10094 decayed slowly and quietly and will rotate over the southwest limb 
on September 10. Region 10095 decayed further and had only a few small trailing 
spots left by midnight. Region 10096 decayed and lost most of its remaining 
penumbral area, the region could become spotless before reaching the southwest 
limb. Region 10097 decayed and was spotless by early evening. Region 10099 
decayed and became spotless early in the day. Region 10100 decayed slowly and 
quietly. Region 10101 decayed and could soon become spotless again. Region 10103 
developed slowly and quietly. Region 10104 decayed slowly and was quiet. Region 
10105 changed its appearance by losing several spots in the southern part of the 
main penumbra and developing new leading spots. Another large penumbra rotated 
into view at the southeast limb east southeast of region 10105. SEC/NOAA chose 
to group this penumbra with region 10105 instead of numbering a separate region. 
Time will tell if that decision was correct. New region 10106 emerged in the 
northeast limb. New region 10107 rotated into view at the northeast limb.
Flares and CMEs
A total of 4 C and 1 M class events was recorded on September 8. Region 10105 
produced an M1.5 flare at 01:43 UTC, a weak type II radio sweep was associated 
with this event. Region 10107 generated a C4.0 flare at 14:57 UTC.
The background x-ray flux is at the class B8 level.
Coronal holes
An extension of the southern polar coronal hole was in a geoeffective position 
on September 7-8.
Forecast
The geomagnetic field is expected to be quiet to unsettled on September 9. Quiet 
to active is possible on September 10-11 due to a coronal stream. 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.
Active solar regions (Recent map)
      Solar regionDate numberedActual no. sunspotsLocation at 
      midnightAreaClassificationComment
      100942002.08.291S18W690110HSX 
      100952002.08.2911N08W560160FSO 
      100962002.08.3014S16W440080EAOtoo many spots,
      area near 0050
      100972002.08.312N13W720030CSO now spotless
      100982002.08.31 S10W28  plage
      100992002.09.011S03W750000AXXnow spotless
      101002002.09.014S19W230050DSO
      101012002.09.017N04W260040DSO
      101022002.09.02 N08W13  plage
      101032002.09.0327N16E060200DAI
      101042002.09.071N10E440030HSX
      101052002.09.0725S07E660850FKObeta-gamma-delta
      101062002.09.083N28E500010BXO
      101072002.09.085N11E700060CSO
      Total number of sunspots:101

Monthly solar data
      MonthAverage solar fluxInternational sunspot numberSmoothed sunspot number
      2000.04184.2125.5120.8
      cycle 23 sunspot max. 
      2000.07202.3170.1119.8
      2001.08162.9106.4113.6 (+1.8)
      2001.09233.2 150.7114.1 (+0.5)
      2001.10207.6125.5114.0 (-0.1)
      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)
      2002.03179.598.4(113.2 predicted, -1.5)
      2002.04189.8120.4(108.7 predicted, -4.5)
      2002.05178.4120.8(104.2 predicted, -4.5)
      2002.06148.788.5(99.7 predicted, -4.5)
      2002.07173.599.9(94.9 predicted, -4.8)
      2002.08183.6116.4(90.8 predicted, -4.1)
      2002.09178.1 (1)57.0 (2)(87.1 predicted, -3.7)

1) Running average based on the daily 20:00 UT 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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