Solar Terrestrial Activity Report

Last update September 13, 2002 at 04:15 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 active on September 12. Solar wind speed 
ranged between 444 and 561 km/sec under the influence of a coronal stream.
Solar flare activity was low. Solar flux was 212.4, the planetary A index was 17 
(3-hour planetary K indices: 4343 4332, Boulder K indices: 3342 4232). Region 
10100 decayed and lost its only remaining spot shortly after noon. Region 10103 
decayed slowly and quietly. Region 10104 reemerged briefly with a few spots. 
Region 10105 lost some spots north and west of the main penumbra, however, new 
spots emerged south of that penumbra. The trailing part of the region (which 
should be split into a separate region) stretched somewhat but still has a 
magnetic delta structure. The region could produce M class flares. Region 10107 
was mostly unchanged spotwise. The positive and negative polarities are slowly 
separating and the region could soon begin to decay. Region 10108 decayed and 
was spotless before noon. Region 10109 decayed slowly as it lost several spots. 
Region 10110 decayed slowly and quietly. New region 10111 emerged just east of 
the central meridian in the northeast quadrant. New region 10112 emerged briefly 
near the center of the disk. New region 10113 emerged in the northwest quadrant, 
at least according to SEC/NOAA. Unfortunately there are no traces of this region 
in any available images.
Flares and CMEs
A total of 8 C class events was recorded on September 12. Region 10107 produced 
a C4.1 flare at 00:18, a C2.8 flare at 07:14 and a C2.5 flare at 11:53 UTC. 
Region 10105 generated a C1.0 flare at 13:38, a C3.1 long duration event peaking 
at 21:23 and a C1.4 flare at 23:37 UTC:
The background x-ray flux is at the class B7 level.
Coronal holes
No obvious coronal holes are currently rotating into geoeffective positions.
Forecast
The geomagnetic field is expected to be quiet to unsettled on September 13-15. 
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)
Solar regionDate numberedActual no. sunspotsLocation at 
            midnightAreaClassificationComment
    100982002.08.31 S10W80  plage
    101002002.09.013S16W750030CAOat best a 0010 HRX
            region, was spotless after
            noon. Poor observation
            by SEC/NOAA
    101012002.09.01 N02W76  plage
    101022002.09.02 N08W65  plage
    101032002.09.0328N16W450330EAI 
    101042002.09.072N09W100000AXXnow spotless
    101052002.09.0758S08E161180FKIbeta-gamma-delta
            actually two separate
            regions
    101062002.09.08 N27W03  plage
    101072002.09.0820N11E160190DAI 
    101082002.09.101S24E200000AXXspotless before noon
    101092002.09.1015S08W100060DAO
    101102002.09.109N19W090030DSO
    101112002.09.126N11E010010BXO
    101122002.09.125N00E040010AXXnow spotless
    101132002.09.121N30W380010AXXspotless in all
            available images
    Total number of sunspots:148
    
    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)
    2002.09189.9 (1)86.7 (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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