Solar Terrestrial Activity Report

Last update March 18, 2000 at 04:45 UTC.
[Solar and geomagnetic data - last 4 weeks (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update March 2, 2000)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update March 2, 2000)]
[Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update March 2, 
2000)]
[Historical solar and geomagnetic data charts 1954-1999]
Recent development
The geomagnetic field was quiet on March 17. Solar wind speed ranged between 306 
and 355 km/sec.
Solar flare activity was moderate. Solar flux was 192.4, the planetary A index 
was 6 (3-hour K indices: 2122 2222, Boulder K indices: 1123 2210). Region 8901 
was quiet and stable and rotated off the visible disk early today. Region 8906 
decayed slowly and will likely continue to produce C flares and occasional minor 
M flares. There is a chance of a major flare as well. Region 8909 was quiet and 
stable. Region 8910 developed slowly and has minor M class flaring potential. 
Region 8911 was quiet and stable and will rotate over the west limb today. 
Region 8913 developed slowly and could produce further C flares. Region 8914 
decayed into spotless plage. Region 8915 was quiet and stable. New region 8916 
rotated partly into view at the northeast limb. Further regions will rotate into 
view over the next couple of days.
Flares and CMEs
11 C flares and 1 M flare were recorded on March 17. Region 8906 produced a C5.8 
flare at 04:58, a C1.7 flare at 07:20, a C3.3 flare at 07:30, a C1.8 flare at 
19:55, a C3.6 flare at 22:00 UTC and an M1.1 flare at 11:25 UTC. Region 8910 
generated a C4.3 flare at 08:17 and a C1.8 flare at 09:38 UTC. Region 8913 was 
the source of a C1.7 flare at 17:17 UTC. A long duration C6 event began before 
midnight and peaked early on March 18, its source was in region 8906.
The background x-ray flux is at the class C1 level.
Coronal holes
The large coronal hole that has been around for several months has been split 
into three smaller coronal holes. One is in the northern hemisphere and will 
rotate into a geoeffective position on March 19, another (and fairly small one) 
is in the southern hemisphere and could rotate into a geoeffective position on 
March 20. The third, and largest remaining part, is trans equatorial and should 
rotate into a geoeffective position on March 21-22.
Forecast
The geomagnetic field is expected to be quiet to unsettled on March 18-20. A 
coronal hole related disturbance is likely to start on March 22 and could cause 
unsettled to active intervals until March 25. 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
            8901200003051S15W860000AXX 
            890220000306 S17W69  plage
            89062000030820S16W490610DKIbeta-gamma
            890820000309 S23W31  plage
            8909200003113S29E010020CSO 
            89102000031234N11E050250DAI 
            8911200003141N08W790010HRX 
            891220000314 N15W41  plage
            89132000031411S16E300100DAO 
            891420000316 N16W08  plage
            8915200003161N23E620130HSX 
            8916200003171N12E740070HSX 
            Total number of sunspots:72 
    
Monthly solar data
MonthAverage solar fluxInternational sunspot numberSmoothed sunspot 
            number
            1999.02141.966.184.6 (+2.0)
            1999.03126.369.1 83.8 (-0.8)
            1999.04117.263.9 85.4 (+1.6)
            1999.05148.4106.3 90.4 (+5.0)
            1999.06169.8137.7 93.0 (+2.6)
            1999.07165.6113.5 94.4 (+1.4)
            1999.08170.793.7 97.5 (+3.1)
            1999.09135.770.9 (102.6 predicted, +5.1)
            1999.10164.8116.4 (107.7 predicted, +5.1)
            1999.11191.5132.7 (110.2 predicted, +2.5)
            1999.12169.886.4 
            2000.01158.190.2 
            2000.02174.1112.3 
            2000.03204.1 (1)101.8 (2) 
    
1) Running average based on the daily 20:00 UTC solar flux value at 2800 MHz..
2) Unofficial, accumulated value. The official value 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 in solar 
links. Comments and suggestions are always welcome.


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