Solar Terrestrial Activity ReportSolar Terrestrial Activity Report

Last update February 28, 2002 at 05:25 UTC.
[Solar and geomagnetic data - last 4 weeks (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update February 2, 2002)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update February 2, 2002)]
[Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update February 2, 
2002)]
[Historical solar and geomagnetic data charts 1954-2001 (last update January 12, 
2002)]
Recent development
The geomagnetic field was quiet on February 27. Solar wind speed ranged between 
314 and 362 km/sec. An unexpected solar wind shock was observed at 03:52 UTC on 
February 28 at SOHO. Solar wind speed increased abruptly from 340 to 380 km/sec. 
The source of this CME is not clear.
Solar flare activity was moderate. Solar flux was 198.6, the planetary A index 
was 4 (3-hour K indices: 2011 2222, Boulder K indices: 2011). Region 9837 
decayed further and was spotless by early evening. Region 9839 decayed slowly 
and could still produce minor M class flares. Region 9842 decayed slowly and 
quietly. Region 9843 developed slowly and quietly. Region 9844 developed slowly 
and was quiet, minor M class flares are possible. Region 9845 developed 
significantly and could produce minor M class flares. Region 9846 decayed and is 
rotating quietly over the southwest limb. Region 9847 decayed slowly and could 
soon become spotless. Region 9848 was mostly unchanged and quiet. New region 
9850 emerged in the northwest quadrant.

Flares and CMEs
A total of 5 C and 2 M class events were recorded on February 27. Region 9839 
produced a C7.1 flare at 00:47, an M1.6 flare at 15:58 and a C7.9 flare at 20:58 
UTC. Old region 9830 produced a long duration M2.2 event from behind the 
southwest limb. The event began at 23:56 UTC and peaked on Feb.28 at 00:12 UTC.
The background x-ray flux is at the class C1 level.

Coronal holes
A recurrent trans equatorial coronal hole will rotate into a geoeffective 
position on March 1 and could cause unsettled to minor storm conditions on March 
4-5. A coronal hole in the southern hemisphere rotated across the central 
meridian on February 26 but was likely too far to the south to cause a 
geomagnetic disturbance.
Forecast
The geomagnetic field is expected to be quiet to active on February 28 and quiet 
to unsettled on March 1-3. Long distance medium wave (AM) band propagation along 
east-west paths over high and upper middle latitudes is fair.
      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
      98342002.02.19 N03W52  plage
      98372002.02.202N10W230000AXXnow spotless
      98392002.02.2111S18W750250EAO
      98402002.02.21 S11W06  plage
      98412002.02.22 S22W83  plage
      98422002.02.226S19W630210DAO 
      98432002.02.2210S26W080020DSO 
      98442002.02.2322N22W210190DAI 
      98452002.02.2322N17E210160EAI 
      98462002.02.243S03W820180EAO 
      98472002.02.244S14E100010BXO 
      98482002.02.258S20E050050DAO 
      98492002.02.25 N23E42  plage
      98502002.02.274N27W510030CAO 
      Total number of sunspots:92 

Monthly solar data
      MonthAverage solar fluxInternational sunspot numberSmoothed sunspot number
      2000.04184.2125.5120.8
      cycle 23 sunspot max. 
      2000.07202.3170.1119.8
      2000.12173.6104.4112.0 (-0.7)
      2001.01166.695.6108.7 (-3.3)
      2001.02146.680.6104.1 (-4.6)
      2001.03177.7113.5104.8 (+0.7)
      2001.04177.7107.7107.6 (+2.8)
      2001.05147.196.6108.7 (+1.1)
      2001.06173.0134.0109.8 (+1.1)
      2001.07131.382.2111.7 (+1.9)
      2001.08162.9106.8(113.5 predicted, +1.8)
      2001.09233.2 150.7(113.3 predicted, -0.2)
      2001.10207.6125.6(111.0 predicted, -2.3)
      2001.11210.6106.5(109.6 predicted, -1.4)
      2001.12235.1131.8(106.2 predicted, -3.4)
      2002.01226.6113.9(102.6 predicted, -3.6)
      2002.02205.1 (1)187.8 (2)(101.2 predicted, -1.4)

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 25-40% 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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