Solar Terrestrial Activity ReportSolar Terrestrial Activity Report

Last update February 27, 2002 at 04:25 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 to unsettled on February 26. Solar wind speed 
ranged between 309 and 362 km/sec.
Solar flare activity was low. Solar flux was 207.5, the planetary A index was 8 
(3-hour K indices: 2232 2223, Boulder K indices: 1233 2322). Region 9830 rotated 
off the visible disk. Region 9837 decayed further and could soon become 
spotless. Region 9839 changed a lot throughout the day, losing spots in some 
parts of the region while gaining new spots in other sections. A minor M class 
flare is possible before the region rotates off the visible disk on March 1. 
Region 9841 decayed further and was spotless by early evening. Region 9842 
developed early in the day, then began to decay losing most of the intermediate 
spots as well as a large part of the trailing spots. Region 9843 decayed and 
could soon become spotless. Region 9844 decayed slowly and was quiet. Region 
9845 was mostly unchanged and quiet. Region 9846 developed early in the day, 
then began to decay and has lost most of its intermediate spots by early Feb.27. 
Region 9847 decayed and could soon become spotless. Region 9848 developed slowly 
and quietly. Region 9849 decayed and was spotless by the end of the day.

Flares and CMEs
A total of 7 C class events were recorded on February 26. Region 9839 produced a 
C4.4 flare at 06:56 UTC. Region 9830 generated a C9.6 flare at 10:27 UTC and a 
long duration C6.1 event peaking at 16:32 UTC. Region 9845 was the source of a 
C3.5 flare at 13:55 UTC, the flare was associated with a moderate type II radio 
sweep. Region 9837 managed a C2.3 flare at 19:19 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 2 and could cause unsettled to minor storm conditions on March 
5-6. A coronal hole in the southern hemisphere rotated across the central 
meridian on February 26 but is likely too far to the south to cause a 
geomagnetic disturbance.
Forecast
The geomagnetic field is expected to be mostly quiet on February 27 to March 1. 
Long distance medium wave (AM) band propagation along east-west paths over high 
and upper middle latitudes is fair to good.
      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
      98292002.02.14 S06W79  plage
      98302002.02.144S17W920170EAObeta-gamma
      98322002.02.18 S15W81  plage
      98342002.02.19 N03W39  plage
      98372002.02.204N09W090020DSO 
      98382002.02.21 N05W84  plage
      98392002.02.2116S17W620170DAI
      98402002.02.21 S11E07  plage
      98412002.02.221S22W700020HSXnow spotless
      98422002.02.2213S19W490240DKO 
      98432002.02.227S26E060030CSO 
      98442002.02.2320N22W080120DAI 
      98452002.02.2311N17E350130DAO 
      98462002.02.248S03W680180DAO 
      98472002.02.248S14E240040CSO 
      98482002.02.2510S20E200060DSO 
      98492002.02.251N23E550000AXXnow spotless
      Total number of sunspots:103 

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)
      2002.02205.3 (1)180.9 (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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